Skip main navigation

Inducing Persistent Flow Disturbances Accelerates Atherogenesis and Promotes Thin Cap Fibroatheroma Development in D374Y-PCSK9 Hypercholesterolemic Minipigs

Originally published 2015;132:1003–1012



Although disturbed flow is thought to play a central role in the development of advanced coronary atherosclerotic plaques, no causal relationship has been established. We evaluated whether inducing disturbed flow would cause the development of advanced coronary plaques, including thin cap fibroatheroma.

Methods and Results—

D374Y-PCSK9 hypercholesterolemic minipigs (n=5) were instrumented with an intracoronary shear-modifying stent (SMS). Frequency-domain optical coherence tomography was obtained at baseline, immediately poststent, 19 weeks, and 34 weeks, and used to compute shear stress metrics of disturbed flow. At 34 weeks, plaque type was assessed within serially collected histological sections and coregistered to the distribution of each shear metric. The SMS caused a flow-limiting stenosis, and blood flow exiting the SMS caused regions of increased shear stress on the outer curvature and large regions of low and multidirectional shear stress on the inner curvature of the vessel. As a result, plaque burden was ≈3-fold higher downstream of the SMS than both upstream of the SMS and in the control artery (P<0.001). Advanced plaques were also primarily observed downstream of the SMS, in locations initially exposed to both low (P<0.002) and multidirectional (P<0.002) shear stress. Thin cap fibroatheroma regions demonstrated significantly lower shear stress that persisted over the duration of the study in comparison with other plaque types (P<0.005).


These data support a causal role for lowered and multidirectional shear stress in the initiation of advanced coronary atherosclerotic plaques. Persistently lowered shear stress appears to be the principal flow disturbance needed for the formation of thin cap fibroatheroma.


Coronary heart disease is projected to remain the worldwide leading cause of death until 2030.1 Coronary heart disease is a major cause of morbidity and reduced quality of life with enormous economic consequences.2,3 Atherosclerosis, a multifocal lipid-driven inflammatory process, is the principal underlying pathology in patients with coronary heart disease, which commonly presents clinically with symptoms secondary to luminal narrowing of an epicardial coronary artery or an acute coronary syndrome. The latter is a major cause of coronary heart disease death and most commonly results from rupture at the site of a thin cap fibroatheroma (TCFA) leading to coronary thrombosis.4

Clinical Perspective on p 1012

The precise environmental cues that lead plaques toward an advanced and high-risk phenotype are not yet fully elucidated, but disturbed blood flow is thought to play a central role in both lesion initiation and progression.5 Disturbed flow is most frequently quantified by metrics of shear stress, which is the frictional force imposed by blood flowing over the endothelial surface, and association between these metrics and coronary atherosclerotic lesion stage have been demonstrated in vivo in both animal models69 and patients.10,11 However, few studies have investigated the impact of prevalent shear conditions on the longitudinal development of advanced coronary plaques, wherein they report discrepant results. Previous experimental studies68,12 have reported TCFA development in arterial segments with persistently low time-averaged wall shear stress (WSS) in diabetic hypercholesterolemic pigs. By contrast, clinical studies11 suggested that regions of high WSS were associated with the development of features of plaque vulnerability. This work also showed an association between low WSS and regional plaque progression, consistent with the findings of the Prediction of Progression of Coronary Artery Disease and Clinical Outcome Using Vascular Profiling of Shear Stress and Wall Morphology (PREDICTION) trial.10 Although informative, these important studies do not confirm a causal role for metrics of disturbed WSS in inducing the formation and progression of advanced coronary plaques.

In the current study, we hypothesized that: (1) inducing disturbed blood flow initiates the development of advanced coronary plaque types, including TCFA, and (2) different longitudinal patterns of low, multidirectional, and high WSS metrics determine plaque morphology. To test these hypotheses, we developed a stenotic shear modifying stent (SMS)13 that could be placed percutaneously to induce regions of persistent blood flow perturbations within the coronary arteries of D374Y-PCSK9 hypercholesterolemic transgenic minipigs.14 Our results provide evidence for a causal role of disturbed flow in the development of advanced coronary plaques and extend our previous work demonstrating that inducing disturbed blood flow in a carotid artery of hypercholesterolemic mice15,16 causes the development of TCFA-like plaques.


Detailed methods are available in the online-only Data Supplement, and the study protocol is summarized in Figure I in the online-only Data Supplement. All animal experiments were performed in accordance with the ethical and welfare regulations of the University of Aarhus and approved by the Danish Animal Experiments Inspectorate. In brief, SMSs were implanted into either the left anterior descending or left circumflex arteries of hypercholesterolemic D374Y-PCSK9 transgenic minipigs (n=6), with the unstented artery serving as a control.14 Serial intracoronary frequency-domain optical coherence tomography (FD-OCT) and Doppler flow velocity measurements were obtained at 0 (baseline), 0+ (immediately poststent), 19 weeks, and 34 weeks. From these data, the 3-dimensional (3-D) geometry of each artery was reconstructed, and computational fluid dynamics (CFD) was performed to compute established and custom WSS metrics of disturbed flow. To correlate computed WSS metrics to plaque morphology, vessel segments were excised proximal and distal to the SMS in the instrumented artery and in a comparable region of the uninstrumented control artery at the final study time point. The segments were serially sectioned, and alternating sections were stained with hematoxylin and eosin, picrosirius red (collagen), and muramidase (pan macrophage). Stained histological sections from each pig were imaged, contoured manually, and accurately coregistered to the corresponding segments of the in vivo 3-D reconstructed arteries of that pig over all time points, to evaluate on a local basis (3.6° circumferentially and ≈105 μm axially) the time course of the change in magnitude of each WSS metric within each plaque type. Plaques were independently classified by expert histopathologists, who were blinded to CFD results, as TCFA, fibrous cap atheroma (FCA), pathological intimal thickening (PIT), xanthoma (XA), intimal thickening (IT), or normal vessel wall (NOR). A color-coding system was used to segment plaque type continuously around the circumference of each hematoxylin and eosin–stained section (Figure II in the online-only Data Supplement). The primary readout was the mean of each WSS metric within each of the plaque types identified in each histological section, averaged over all sections containing that plaque type across all pigs. The accuracy of this workflow was confirmed in a formal error analysis (see Methods in the online-only Data Supplement).

Statistical Analysis

Variables (stenosis area, blood velocity, and total cholesterol) are reported as mean±standard deviation. Some variables (WSS metrics of disturbed flow and metrics of plaque size) were log-transformed and reported as geometric mean (GM) with 95% confidence interval (CI). All statistical analyses were performed by using a linear mixed-effects model to compare continuous dependent variables and various independent categorical variables, including: plaque type or group (fixed effect), time (fixed effect), and subject (random effect attributable to repeated measures of multiple histological sections within each pig). Comparisons between normally distributed variables are expressed as an arithmetic mean difference with 95% CI, and log-transformed distributed variables are expressed as a geometric mean ratio (GMR) with 95% CI. Both outputs come directly from the mixed model with an associated P value. All P values generated from the linear mixed-effect model and reported in the article have been systematically Bonferroni corrected by multiplying each P value by the appropriate number of comparisons. Statistical significance was based on these corrected P values being <0.05. All statistical analyses were performed in Stata version 13 (StataCorp, College Station, TX).


One pig died of acute stent thrombosis immediately after SMS implantation. Of the remaining 5 pigs, 4 animals completed the entire study protocol, with 1 animal dying after developing stent thrombosis following the completion of intracoronary imaging at the 19-week time point. A total of 5957 FD-OCT frames were contoured manually to allow reconstruction and CFD modeling for the calculation of WSS in 38 vessels composed of both instrumented and control arteries over all time points in 5 pigs. Histology sections were coregistered to the corresponding 3-D reconstructed arteries. Local plaque type was manually segmented in hematoxylin and eosin–stained sections (n=538). Regional overlaps between these histological measures and WSS metrics of disturbed flow were quantified.

SMS Induced Atherogenesis and Advanced Plaque Development

We observed accelerated atherosclerosis resulting from SMS placement. In comparison with control regions, the segment downstream of the SMS had moderately increased external elastic lamina area (GM, 2.1; 95% CI, 2.0–2.2 mm2 versus GM, 1.4; 95% CI, 1.3–1.5 mm2 and GMR, 1.6; 95% CI, 1.4–1.8; P<0.001) and large increases in plaque area (GM, 1.3; 95% CI, 1.1–1.5 mm2 versus GM, 0.2; 95% CI, 0.2–0.3 mm2 and GMR, 6.0; 95% CI, 4.7–8.0; P<0.001). The segment upstream of the SMS had similar increases in external elastic lamina area (GM, 2.1; 95% CI, 1.9–2.3 mm2 versus GM, 1.4; 95% CI, 1.3–1.5 mm2 and GMR, 1.5; 95% CI, 1.3–1.7; P<0.001) but plaque area only increased modestly (GM, 0.3; 95% CI, 0.3–0.4 mm2 versus GM, 0.2; 95% CI, 0.2–0.3 mm2 and GMR, 1.5; 95% CI, 1.1–2.0; P=0.012), which was significantly less than in the downstream segment (GMR, 4.0; 95% CI, 3.3–5.0 in downstream versus upstream plaque area; P<0.001). Strikingly, plaque burden was ≈3-fold higher in the segment downstream of the SMS than in both the SMS upstream (GMR, 3.4; 95% CI, 2.9–4.1; P<0.001) and control artery segments (GMR, 3.5; 95% CI, 2.8–4.4; P<0.001; Figure 1A).

Figure 1.

Figure 1. A, Box-and-whisker plot of plaque burden computed as plaque (or intima) area divided by media area for each histological section and scaled by an assumed normal intima-media areal ratio of 0.225 (linear ratio is 0.3). Plaque burden was ≈3-fold higher downstream of the SMS in comparison with the SMS upstream and control artery segments (***P<0.001). Red dots indicate outliers. B, Representative histological sections of advanced plaque types in the vessel segment downstream of the SMS. Advanced lesions were identified based on the presence of a necrotic core, inflammation (ie, accumulation of macrophages), and the presence of a fibrous cap. TCFA was defined when fibrous cap thickness was ≤65 μm (white arrow indicates TCFA cap in 10× picrosirius red image, which is further magnified to 40× in the entire bottom row of images). The white box in each 2× image indicates region of 10× image. FCA indicates fibrous cap atheroma; PIT, pathological intimal thickening; SMS, shear modifying stent; and TCFA, thin cap fibroatheroma.

Sections from the segment downstream of the SMS exhibited plaques at varying stages of advancement (Figure 1B), including NOR (34%), IT (20%), XA (17%), PIT (22%), FCA (4%), and TCFA (3%). FCA and TCFA lesions contained a large necrotic core, macrophage infiltration, and a fibrous cap (≤65 μm for TCFA) with newly deposited collagen, similar to human lesions (Figure 1B). The following plaque types developed in the region upstream of the SMS: NOR (36%), IT (29%), XA (10%), PIT (20%), and FCA (5%). No TCFA was observed. Sections from segments of the uninstrumented artery exhibited NOR (41%), IT (30%), XA (5%), and PIT (24%), but no FCA or TCFA was observed (Figure III in the online-only Data Supplement).

SMS Implantation Caused Persistent WSS Perturbations

The arithmetic mean initial maximum areal stenosis created by the SMS was 62.6±7.0% (n=5). There was a progressive increase in stenosis severity to 83.9±3.1% at 34 weeks (arithmetic mean difference, 20.9; 95% CI, 14.5–27.4% at 34 weeks versus immediately post-SMS; P<0.001) because of neointimal hyperplasia within the SMS (Figure 2A and 2B). The stenosis resulted in a reduction of mean blood velocity at the inlet of the instrumented vessel from 147.8±41.0 at baseline to 90.7±19.2 mm/s at 34 weeks (arithmetic mean difference, –57.1; 95% CI, –93.7 to –20.3 mm/s at 34 weeks versus baseline; P=0.018). The change in blood velocity in the control vessel over time was not statistically significant (P=0.55; Figure 2C). The reduced blood velocity caused a concomitant reduction in WSS in the instrumented vessel (Figure 2D). Notably, in the region downstream of the SMS, the accelerated blood flow exiting the SMS was directed toward the outer curvature of the vessel in a concentrated stream, causing regions of markedly increased flow localized to the outer curvature. This high kinetic energy in the concentrated stream induced flow separation and vortex formation, causing large regions with low and multidirectional flow on the inner curvature (Figure 2E). WSS metrics with the largest positive change from baseline values over time were the low shear index (LSI), indicating regions with lowered WSS; high shear index (HSI), indicating regions with increased WSS; and a variant of the transverse wall shear stress (tSS; Figure 2D), indicating multidirectional flow. We therefore focused on these metrics for the remainder of the study.

Figure 2.

Figure 2. A, Representative FD-OCT images of the maximum stenosis within the implanted SMS at 0 (baseline), 0+ (immediately post-SMS), 19 weeks, and 34 weeks showing increased severity of the stenosis attributable to intimal hyperplasia. B, Maximum areal stenosis (%) averaged over all pigs, which increased from 0+ to 34 weeks (***P<0.001). C, Mean inlet blood velocity (m/s) decreased in the instrumented artery over time (*P<0.02 compared with baseline), whereas the contralateral control artery did not significantly change. D, Box-and-whisker plot of the relative change from baseline of 8 WSS metrics (see Methods in the online-only Data Supplement for list and definitions) in the instrumented downstream segment, computed as the difference of each metric from baseline over all pigs and all post-SMS implant time points, and then scaled by the maximum median of all metrics (WSS). The parameters in which SMS implant caused the greatest positive change were LSI, HSI, and tSS. E, Blood velocity and streamlines from CFD in the instrumented and contralateral control arteries of 1 representative pig. The instrumented vessel exhibited high flow on the outer curvature, and low and multidirectional flow on the inner curvature, whereas the control artery maintained a normal and nearly homogeneous flow profile. At select axial locations in each vessel, cross-sections are provided to show the distribution of velocity. In the bar plots (B and C), data are expressed as mean±SD. CFD indicates computational fluid dynamics; FD-OCT, frequency domain optical coherence tomography; HSI, high shear index; LSI, low shear index; SD, standard deviation; SMS, shear modifying stent; tSS, transverse wall shear stress; and WSS, wall shear stress.

Advanced Plaques Were Initiated by Low and Multidirectional WSS

After observing that placement of the SMS increased LSI, HSI, and tSS, we next evaluated whether any of these metrics of disturbed flow preferentially colocalized to regions of particular plaque types immediately after SMS implantation (t=0+) to explore the initiating stimulus for those plaques. Plaques were initially grouped as advanced lesions (TCFA, FCA, and PIT), early lesions (XA and IT), or normal vessel wall (NOR) in the segments upstream and downstream of the SMS, and the uninstrumented control artery of all pigs, as well. In all histological sections, we quantified the geometric mean of each WSS metric within each plaque group at t=0+ (Figure 3). LSI within advanced lesions located in the downstream segment (n=125 sections) was significantly higher than those in the upstream (GMR, 29.3; 95% CI, 20.7–41.6; n=86; P<0.002) and control segments (GMR, 17.9; 95% CI, 10.9–29.3; n=33; P<0.002). LSI, which is a measure that increases in value as WSS reduces, was also significantly greater in advanced than in early lesions (GMR, 5.5; 95% CI, 4.1–7.3; P<0.002) and normal vessel wall (GMR, 6.9; 95% CI, 5.2–9.1; P<0.002) in the instrumented downstream segment (Figure 3A). By comparison, HSI, which is a measure that increases in value as WSS increases, exhibited a reverse pattern in the downstream segment with reduced values in advanced lesions (except FCA at 19 weeks, see below) that were significantly lower in comparison with early lesions (GMR, 0.62; 95% CI, 0.51–0.76; P<0.002) and normal vessel (GMR, 0.46; 95% CI, 0.38–0.56; P<0.002; Figure 3B). Similar to LSI in the downstream segment, tSS had larger values in advanced lesions than in both early lesions (GMR, 1.7; 95% CI, 1.5–1.9; P<0.002) and normal vessel (GMR, 1.8; 95% CI, 1.6–2.0; P<0.002; Figure 3C). Overall, the striking colocalization of advanced lesions to regions of lowered WSS (LSI) and multidirectional WSS (tSS) within the downstream segment, where plaque burden was ≈3-fold higher in comparison with other regions, suggests that both patterns of disturbed flow contributed to their initiation.

Figure 3.

Figure 3. LSI, HSI, and tSS grouped by plaque type (advanced: TCFA, FCA, and PIT; early: IT and XA; and normal wall) within each of the vessel segments at immediately post-SMS implantation (time=0+) and scaled by the maximum value of the 3 metrics (LSI). A, Of all WSS metrics, LSI had the highest relative magnitude within advanced lesions in the instrumented downstream segment, which was statistically higher than LSI within advanced lesions of other vessel segments (**P<0.002) and other plaque groups in the downstream segment (**P<0.002). B, HSI was nearly exclusively present in the instrumented downstream segment. Interestingly, maximal values within this segment were lowest in advanced lesions in comparison with early lesions (**P<0.002) and normal wall (**P<0.002). C, tSS was similar to LSI with highest values in regions of advanced lesions within the instrumented downstream segment that were statistically different from those in other segments (**P<0.002) and different from early lesions (**P<0.002) and normal wall (**P<0.002) in the downstream segment. *Indicates statistically higher values of the given WSS metric within the plaque group designated by the bar over which it is placed vs the same plaque group in other vessel segments (control, Δ; instrumented upstream, Θ; and instrumented downstream, Ξ) and different plaque groups within the same segment (advanced, χ;, early, ψ; and normal, ω). Data are expressed as geometric mean plus upper limit of 95% CI. CI indicates confidence interval; FCA, fibrous cap atheroma; HSI, high shear index; IT, intimal thickening; LSI, low shear index; PIT, pathological intimal thickening; SMS, shear modifying stent; TCFA, thin cap fibroatheroma; tSS, transverse wall shear stress; WSS, wall shear stress; and XA, xanthoma.

Time Course and Magnitude of Disturbed WSS Determined Final Plaque Type

Next, we determined whether each plaque type experienced a different time course of disturbed flow in the segment downstream of the SMS (Figure 4). TCFA, FCA, and PIT were observed in 2 of 5, 3 of 5, and 5 of 5 animals, respectively. Over all postinstrumentation times, TCFA regions demonstrated higher LSI values (Figure 5A) in comparison with FCA (GMR, 1.8; 95% CI, 1.3–2.5; P<0.005) and PIT (GMR, 1.4; 95% CI, 1.1–1.9; P=0.25), although only the comparison with FCA was statistically significant. LSI in TCFA was also significantly higher in comparison with XA (GMR, 1.94; 95% CI, 1.47–2.56; P<0.005), IT (GMR, 2.75; 95% CI, 2.10–3.58; P<0.005), and normal vessel wall (GMR, 2.66; 95% CI, 2.05–3.46; P<0.005). In addition, LSI values were of greater magnitude in PIT in comparison with values in XA (GMR, 1.4; 95% CI, 1.2–1.6; P<0.005), IT (GMR, 1.9; 95% CI, 1.7–2.2; P<0.005), and normal vessel wall (GMR, 1.9; 95% CI, 1.7–2.1; P<0.005). LSI was also higher in FCA than in IT (GMR, 1.5; 95% CI, 1.2–1.9; P<0.005) and normal wall (GMR, 1.5; 95% CI, 1.2–1.9; P<0.005), but not XA (GMR, 1.1; 95% CI, 0.9–1.4; P=0.90). Interestingly, FCA was also the only advanced plaque with increased HSI (Figure 5B), wherein, at 19 weeks, FCA was increased in comparison with PIT (GMR, 3.2; 95% CI, 1.8– 5.6; P<0.005) and TCFA (GMR, 2.5; 95% CI, 0.9–5.6; P=0.79), although the latter comparison was not significant. Finally, analysis of tSS (Figure 5C) over all postinstrumentation times was not statistically higher between any of the advanced plaque types, and only TCFA and PIT showed any statistically higher values of tSS in comparison with IT (GMR, 1.4; 95% CI, 1.2–1.7 and GMR, 1.3; 95% CI, 1.1–1.4, respectively; P<0.005) and normal vessel wall (GMR, 1.4; 95% CI, 1.2–1.7 and GMR, 1.3; 95% CI, 1.2–1.4, respectively; P<0.005; Figure 5C).

Figure 4.

Figure 4. Top row, Representative 3-D reconstruction of LSI within 1 pig over time (location of SMS indicated by gray lines). Middle and bottom rows, Panels were obtained by computationally isolating the downstream segment (indicated by the black box in the 3-D representation), opening the vessel, and laying it flat (en face with the endothelium facing up) to demonstrate the patterns of LSI, tSS, and plaque type. LSI and tSS are scaled from 0 (null value, indicated by blue) to 1 (maximum value, indicated by red). Plaque type is displayed as a function of plaque burden, ranging from normal wall given by the flesh color to the maximum plaque burden given by the highest color intensity of each plaque type (TCFA, red; FCA, green; PIT, blue; XA, violet; and IT, yellow). The histological data were obtained at the end time point (34 weeks) and then coregistered to the vessel reconstructions at each time point (see Methods in the online-only Data Supplement). FCA indicates fibrous cap atheroma; IT, intimal thickening; LSI, low shear index; PIT, pathological intimal thickening; SMS, shear modifying stent; TCFA, thin cap fibroatheroma; tSS, transverse wall shear stress; and XA, xanthoma.

Figure 5.

Figure 5. LSI, HSI, and tSS within each plaque type of the instrumented downstream segment, averaged over all sections containing that plaque type and all pigs at each time point. These shear metric values are scaled by the maximum over all shear metrics (LSI at 19 weeks) to facilitate comparisons. A, Over all post-SMS implant times as a whole, LSI had a higher presence in regions of TCFA than FCA (P<0.005) and PIT (P=0.25), although the latter was not significant, and all advanced lesions exhibited a higher LSI in comparison with early lesions and normal vessel (P<0.005, except FCA vs XA where P=0.90). B, HSI in the advanced lesions was generally lower than other plaque groups, except regions of FCA at 19 weeks (P<0.005, versus PIT and IT), suggesting that this stimulus may have promoted the stable plaque phenotype. C, tSS initially exhibited a statistically higher presence in regions of advanced plaques in comparison with early lesions and normal vessel (P<0.005) at immediately post-SMS implant, but it was not consistent over time. *Indicates statistically higher values of the given WSS metric within the advanced plaque type designated by the bar over which it is placed vs other plaque types (TCFA, α; FCA, β; PIT, γ; XA, δ; IT, ε; and NOR, ζ). Data are expressed as the geometric mean plus the upper limit of 95% CI. CI indicates confidence interval; FCA, fibrous cap atheroma; HSI, high shear index; IT, intimal thickening; LSI, low shear index; NOR, normal vessel wall; PIT, pathological intimal thickening; SMS, shear modifying stent; TCFA, thin cap fibroatheroma; tSS, transverse wall shear stress; WSS, wall shear stress; and XA, xanthoma.


Previous studies have reported the association between naturally occurring disturbed blood flow and the development of atherosclerotic lesions.611 These investigations have supported the hypothesis that persistent, low WSS may initiate and advance the development of high-risk plaque features, but do not prove its causal role. In the current study, we imposed a persistent perturbation of local WSS by implantation of a SMS. The main findings of our study were, first, that SMS implantation induced a heterogeneous pattern of flow disturbance that caused accelerated atherogenesis and formation of advanced plaque types in the coronary arteries of D374Y-PCSK9 hypercholesterolemic minipigs. Second, we observed that the majority of advanced plaques were located in the segment downstream of the SMS (Figure 1) within regions of initially lowered WSS (quantified by LSI) and also multidirectional WSS (quantified by tSS; Figure 3). In contrast, the upstream SMS and control artery segments exhibited little overlap between WSS metrics of disturbed flow and any plaque type (Figure IV in the online-only Data Supplement). Third, we observed that, in comparison with other advanced plaque types, TCFA developed in those locations downstream of the SMS exposed to the largest and most persistent reduction in WSS over the duration of the study (Figure 5A), consistent with previous observations.8 Finally, FCA developed in locations subjected to greater degrees of high WSS (quantified by HSI), particularly at 19 weeks (Figure 5B), which supports the hypothesis that high WSS may promote a stable plaque phenotype. Collectively, these findings demonstrate a causal role for disturbed flow in the formation of advanced plaques, including TCFA, within coronary arteries.

Building on initial studies that suggested a proatherogenic role for low and oscillatory WSS,17,18 we previously reported that placing a constrictive, external cuff to perturb blood flow in the carotid artery of Apo-E knockout mice led to the formation of TCFA upstream and a stable plaque downstream of this device. This approach provided the first evidence for a causal role of disturbed blood flow in vulnerable and stable plaque formation.16 However, their small size and different cardiovascular physiology impose limitations on the study of atherosclerosis progression and predilection sites as it relates to humans. Furthermore, Reynolds and Dean numbers scale with size and are significantly lower in rodent models in comparison with values in humans.19 Recent data also suggest limitations of murine models for studying acute inflammatory disease processes.20 We were therefore motivated to overcome these limitations by studying the coronary arteries of a transgenic hyperlipidemic pig model which, in contrast to murine models, develops human-like advanced plaques.14 Our results are consistent with previous observations that lowering WSS induces TCFA.15,16 We now demonstrate that, in addition to colocalization with regions of early atherosclerotic lesion formation,21 multidirectional WSS may act synergistically with lowered WSS to initiate the development of advanced coronary plaques including TCFA, which has not been reported previously. In addition, our observations that early exposure to raised WSS, quantified by HSI, significantly overlapped with the formation of early plaque types (Figure 3B), and that exposure to high WSS was associated with the development of FCA (Figure 5B), supports further investigation of the hypothesis that high WSS may be protective by inducing the formation of stable plaque phenotypes.

The marked variation in plaque type observed in both the axial and circumferential directions of each instrumented vessel (Figure 4 and Figure II in the online-only Data Supplement) motivated our novel approach to determine how temporal changes in WSS may influence final plaque morphology on a local, high-resolution scale. This type of analysis is important because plaque rupture is likely determined by variations in the biomechanical properties, and possibly endothelial cell mechanobiology, on this scale.22 This approach was enabled by using FD-OCT rather than intravascular ultrasound for 3-D reconstruction of the vessel lumen and its curvature. We performed a detailed error propagation analysis that confirmed an error of <10% for computed WSS despite the use of a commercial FD-OCT system that could not provide ECG-gated acquisitions. In addition, we performed a detailed error analysis of the 3-D histology approach developed for coregistering WSS metrics from CFD to histological data, which demonstrated a circumferential error of 265 μm and an axial error of 340 μm that represent a significant improvement to previous reports from both others68,12,23,24 and ourselves.2529 Importantly, this 3-D histology error analysis included the assessment of the reproducibility of identification of the same vessel segment of interest from the FD-OCT images through time. Therefore, it accounts for small changes in vessel size that may occur over time owing to remodeling or acquisition of the FD-OCT at different average positions within the cardiac cycle (see Methods in the online-only Data Supplement).

Our data show that development of advanced lesions in the SMS-treated artery directly resulted from induced changes in local blood flow. Two new metrics were developed to quantify those changes relative to the instrumented vessel at baseline (ie, before SMS placement) over a continuous range, namely, the LSI and HSI. These metrics require no a priori assumption of a threshold value of WSS for determining nonnormal WSS magnitudes and are applicable to the study of animals of different sizes and humans. This approach may facilitate the evaluation of changes in WSS over time by overcoming potential issues arising from using a global threshold for defining low and high WSS, as previously reported in the literature.68,23,30–32 Interestingly, the GM of the absolute values of WSS within regions of LSI was 0.7 (95% CI, 0.6–0.8) Pa (Figure V in the online-only Data Supplement), which is lower than the binary threshold values of 1 to 1.2 Pa reported previously.68,23,30–32

The finding that low and multidirectional flow accelerated the initiation and development of all advanced plaque types is consistent with previous experimental data demonstrating that such flow disturbances promote a proatherogenic endothelial cell type, which is characterized by the increased expression of proinflammatory adhesion molecules,33,34 impaired nitric oxide production,35 increased production of reactive oxygen species, augmented permeability to low-density lipoprotein,36 and enhanced attraction and adhesion of monocytes. Furthermore, studies in hyperlipidemic mice,37 rabbits,38 pigs,12 and humans10 consistently demonstrate that atherosclerotic lesions preferentially occur in regions with natural low and multidirectional WSS conditions, including curved vessel segments and bifurcations.39

We studied D374Y-PCSK9 transgenic hypercholesterolemic Yucatan minipigs that have growth curves that suit long-term serial invasive follow-up studies and exhibit chronically elevated cholesterol when fed a cholate-free high-fat, high-cholesterol diet, resulting from a gain-of-function mutation in the proprotein convertase subtilisin/kexin type 9 gene resulting in impaired low-density lipoprotein cholesterol clearance. When fed the high-fat, high-cholesterol diet used in this study, these animals typically achieve a total cholesterol of ≈20 mmol/L (≈773 mg/dL) and low-density lipoprotein cholesterol of ≈11 mmol/L (≈425 mg/dL),14 which is similar to the cholesterol levels of animals in the current study (Figure VI in the online-only Data Supplement).

Study Limitations

Several limitations of this study should be considered. First, a small cohort of 5 pigs was studied and human-like fibroatheromata developed in only 3 of 5 animals, including TCFA in 2 of 5 animals. Even with this sample size, the high-resolution analysis provided sufficient power to allow identification of statistically significant associations between WSS metrics and final plaque morphology. However, further studies in a larger cohort are needed to provide sufficient sample size to assess the relative magnitude, sensitivity, and specificity of LSI, HSI, and tSS, or their combination, for precise prediction of the development of each advanced plaque type. Second, the temporal evolution of WSS metrics could be related to plaque morphology only at the final time point, when the animals were euthanized for histology. Further work is needed to evaluate the time course of development of each advanced plaque. Extending the duration of follow-up and high-fat, high-cholesterol diet with further histological evaluation of the proximal portion of the coronary arteries is also needed to enable more detailed comparison of the determinants of advanced plaque development in the uninstrumented and SMS-treated arteries. Our results suggest the utility of this model for longitudinal studies of the development of advanced human-like plaques, including TCFA, especially because advanced plaques develop at a predictable location within the coronary artery tree in a practical timeframe. Finally, in the current study, we principally considered the effect of induced local flow disturbance through placement of the SMS. Although this intervention may induce an altered arterial remodeling response in comparison with that induced by naturally occurring flow disturbances, we suggest that this approach enables direct testing of the causal role of different patterns of flow disturbances on advanced coronary atherosclerotic lesion development and thus complements natural history studies.


We have established a novel model of accelerated atherogenesis and formation of advanced human-like atherosclerotic plaques, including TCFA. This model combined with FD-OCT–derived CFD and 3-D histology provides a new means of studying the biomechanics and mechanobiology of human-like advanced coronary plaques. Our results demonstrate a causal role for lowered and multidirectional WSS within the coronary arteries as determinants of final plaque type. Persistently lowered WSS appears to be the principal hemodynamic disturbance needed for the formation of TCFA. Further investigation to specify the relative contributions of persistently decreased, increased, and altered multidirectional shear stress on the development of each of the different advanced coronary atherosclerotic plaque types is warranted.


We thank Zahra Nasr, Lisa Maria Røge, and Dorte Qualmann for technical assistance.


*Drs Pedrigi and Poulsen contributed equally.

The online-only Data Supplement is available with this article at

Correspondence to Ranil de Silva, MBBS, PhD, National Heart and Lung Institute (Brompton Campus), Imperial College London and NIHR Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust, Level 2 Chelsea Wing, Sydney St, London SW3 6NP, United Kingdom. E-mail


  • 1. Mathers CD, Loncar D. Projections of global mortality and burden of disease from 2002 to 2030.PLoS Med. 2006; 3:e442. doi: 10.1371/journal.pmed.0030442.CrossrefMedlineGoogle Scholar
  • 2. Go AS, Mozaffarian D, Roger VL, Benjamin EJ, Berry JD, Borden WB, Bravata DM, Dai S, Ford ES, Fox CS, Franco S, Fullerton HJ, Gillespie C, Hailpern SM, Heit JA, Howard VJ, Huffman MD, Kissela BM, Kittner SJ, Lackland DT, Lichtman JH, Lisabeth LD, Magid D, Marcus GM, Marelli A, Matchar DB, McGuire DK, Mohler ER, Moy CS, Mussolino ME, Nichol G, Paynter NP, Schreiner PJ, Sorlie PD, Stein J, Turan TN, Virani SS, Wong ND, Woo D, Turner MB; American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Heart disease and stroke statistics–2013 update: a report from the American Heart Association.Circulation. 2013; 127:e6–e245. doi: 10.1161/CIR.0b013e31828124ad.LinkGoogle Scholar
  • 3. Leal J, Luengo-Fernández R, Gray A, Petersen S, Rayner M. Economic burden of cardiovascular diseases in the enlarged European Union.Eur Heart J. 2006; 27:1610–1619. doi: 10.1093/eurheartj/ehi733.CrossrefMedlineGoogle Scholar
  • 4. Falk E, Nakano M, Bentzon JF, Finn AV, Virmani R. Update on acute coronary syndromes: the pathologists’ view.Eur Heart J. 2013; 34:719–728. doi: 10.1093/eurheartj/ehs411.CrossrefMedlineGoogle Scholar
  • 5. Wentzel JJ, Chatzizisis YS, Gijsen FJ, Giannoglou GD, Feldman CL, Stone PH. Endothelial shear stress in the evolution of coronary atherosclerotic plaque and vascular remodelling: current understanding and remaining questions.Cardiovasc Res. 2012; 96:234–243. doi: 10.1093/cvr/cvs217.CrossrefMedlineGoogle Scholar
  • 6. Chatzizisis YS, Baker AB, Sukhova GK, Koskinas KC, Papafaklis MI, Beigel R, Jonas M, Coskun AU, Stone BV, Maynard C, Shi GP, Libby P, Feldman CL, Edelman ER, Stone PH. Augmented expression and activity of extracellular matrix-degrading enzymes in regions of low endothelial shear stress colocalize with coronary atheromata with thin fibrous caps in pigs.Circulation. 2011; 123:621–630. doi: 10.1161/CIRCULATIONAHA.110.970038.LinkGoogle Scholar
  • 7. Koskinas KC, Feldman CL, Chatzizisis YS, Coskun AU, Jonas M, Maynard C, Baker AB, Papafaklis MI, Edelman ER, Stone PH. Natural history of experimental coronary atherosclerosis and vascular remodeling in relation to endothelial shear stress: a serial, in vivo intravascular ultrasound study.Circulation. 2010; 121:2092–2101. doi: 10.1161/CIRCULATIONAHA.109.901678.LinkGoogle Scholar
  • 8. Koskinas KC, Sukhova GK, Baker AB, Papafaklis MI, Chatzizisis YS, Coskun AU, Quillard T, Jonas M, Maynard C, Antoniadis AP, Shi GP, Libby P, Edelman ER, Feldman CL, Stone PH. Thin-capped atheromata with reduced collagen content in pigs develop in coronary arterial regions exposed to persistently low endothelial shear stress.Arterioscler Thromb Vasc Biol. 2013; 33:1494–1504. doi: 10.1161/ATVBAHA.112.300827.LinkGoogle Scholar
  • 9. Thim T, Hagensen MK, Hørlyck A, Kim WY, Niemann AK, Thrysøe SA, Drouet L, Paaske WP, Bøtker HE, Falk E. Wall shear stress and local plaque development in stenosed carotid arteries of hypercholesterolemic minipigs.J Cardiovasc Dis Res. 2012; 3:76–83. doi: 10.4103/0975-3583.95358.CrossrefMedlineGoogle Scholar
  • 10. Stone PH, Saito S, Takahashi S, Makita Y, Nakamura S, Kawasaki T, Takahashi A, Katsuki T, Nakamura S, Namiki A, Hirohata A, Matsumura T, Yamazaki S, Yokoi H, Tanaka S, Otsuji S, Yoshimachi F, Honye J, Harwood D, Reitman M, Coskun AU, Papafaklis MI, Feldman CL; PREDICTION Investigators. Prediction of progression of coronary artery disease and clinical outcomes using vascular profiling of endothelial shear stress and arterial plaque characteristics: the PREDICTION Study.Circulation. 2012; 126:172–181. doi: 10.1161/CIRCULATIONAHA.112.096438.LinkGoogle Scholar
  • 11. Samady H, Eshtehardi P, McDaniel MC, Suo J, Dhawan SS, Maynard C, Timmins LH, Quyyumi AA, Giddens DP. Coronary artery wall shear stress is associated with progression and transformation of atherosclerotic plaque and arterial remodeling in patients with coronary artery disease.Circulation. 2011; 124:779–788. doi: 10.1161/CIRCULATIONAHA.111.021824.LinkGoogle Scholar
  • 12. Chatzizisis YS, Jonas M, Coskun AU, Beigel R, Stone BV, Maynard C, Gerrity RG, Daley W, Rogers C, Edelman ER, Feldman CL, Stone PH. Prediction of the localization of high-risk coronary atherosclerotic plaques on the basis of low endothelial shear stress: an intravascular ultrasound and histopathology natural history study.Circulation. 2008; 117:993–1002. doi: 10.1161/CIRCULATIONAHA.107.695254.LinkGoogle Scholar
  • 13. Foin N, Sen S, Petraco R, Nijjer S, Torii R, Kousera C, Broyd C, Mehta V, Xu Y, Mayet J, Hughes A, Di Mario C, Krams R, Francis D, Davies J. Method for percutaneously introducing, and removing, anatomical stenosis of predetermined severity in vivo: the “stenotic stent.”J Cardiovasc Transl Res. 2013; 6:640–648. doi: 10.1007/s12265-013-9476-x.CrossrefMedlineGoogle Scholar
  • 14. Al-Mashhadi RH, Sørensen CB, Kragh PM, Christoffersen C, Mortensen MB, Tolbod LP, Thim T, Du Y, Li J, Liu Y, Moldt B, Schmidt M, Vajta G, Larsen T, Purup S, Bolund L, Nielsen LB, Callesen H, Falk E, Mikkelsen JG, Bentzon JF. Familial hypercholesterolemia and atherosclerosis in cloned minipigs created by DNA transposition of a human PCSK9 gain-of-function mutant.Sci Transl Med. 2013; 5:166ra1. doi: 10.1126/scitranslmed.3004853.CrossrefMedlineGoogle Scholar
  • 15. Cheng C, Tempel D, van Haperen R, de Boer HC, Segers D, Huisman M, van Zonneveld AJ, Leenen PJ, van der Steen A, Serruys PW, de Crom R, Krams R. Shear stress-induced changes in atherosclerotic plaque composition are modulated by chemokines.J Clin Invest. 2007; 117:616–626. doi: 10.1172/JCI28180.CrossrefMedlineGoogle Scholar
  • 16. Cheng C, Tempel D, van Haperen R, van der Baan A, Grosveld F, Daemen MJ, Krams R, de Crom R. Atherosclerotic lesion size and vulnerability are determined by patterns of fluid shear stress.Circulation. 2006; 113:2744–2753. doi: 10.1161/CIRCULATIONAHA.105.590018.LinkGoogle Scholar
  • 17. Pedersen EM, Oyre S, Agerbaek M, Kristensen IB, Ringgaard S, Boesiger P, Paaske WP. Distribution of early atherosclerotic lesions in the human abdominal aorta correlates with wall shear stresses measured in vivo.Eur J Vasc Endovasc Surg. 1999; 18:328–333. doi: 10.1053/ejvs.1999.0913.CrossrefMedlineGoogle Scholar
  • 18. Davies PF, Polacek DC, Shi C, Helmke BP. The convergence of haemodynamics, genomics, and endothelial structure in studies of the focal origin of atherosclerosis.Biorheology. 2002; 39:299–306.MedlineGoogle Scholar
  • 19. de Crom R, Cheng C, Helderman F, Krams R. Large variations in absolute wall shear stress levels within one species and between species.Atherosclerosis. 2009; 204:16–17; author reply 18. doi: 10.1016/j.atherosclerosis.2008.08.010.CrossrefMedlineGoogle Scholar
  • 20. Seok J, Warren HS, Cuenca AG, Mindrinos MN, Baker HV, Xu W, Richards DR, McDonald-Smith GP, Gao H, Hennessy L, Finnerty CC, López CM, Honari S, Moore EE, Minei JP, Cuschieri J, Bankey PE, Johnson JL, Sperry J, Nathens AB, Billiar TR, West MA, Jeschke MG, Klein MB, Gamelli RL, Gibran NS, Brownstein BH, Miller-Graziano C, Calvano SE, Mason PH, Cobb JP, Rahme LG, Lowry SF, Maier RV, Moldawer LL, Herndon DN, Davis RW, Xiao W, Tompkins RG; Inflammation and Host Response to Injury, Large Scale Collaborative Research Program. Genomic responses in mouse models poorly mimic human inflammatory diseases.Proc Natl Acad Sci U S A. 2013; 110:3507–3512. doi: 10.1073/pnas.1222878110.CrossrefMedlineGoogle Scholar
  • 21. del Alamo JC, Norwich GN, Li YS, Lasheras JC, Chien S. Anisotropic rheology and directional mechanotransduction in vascular endothelial cells.Proc Natl Acad Sci U S A. 2008; 105:15411–15416. doi: 10.1073/pnas.0804573105.CrossrefMedlineGoogle Scholar
  • 22. Pedrigi RM, de Silva R, Bovens SM, Mehta VV, Petretto E, Krams R. Thin-cap fibroatheroma rupture is associated with a fine interplay of shear and wall stress.Arterioscler Thromb Vasc Biol. 2014; 34:2224–2231. doi: 10.1161/ATVBAHA.114.303426.LinkGoogle Scholar
  • 23. Chatzizisis YS, Coskun AU, Jonas M, Edelman ER, Feldman CL, Stone PH. Role of endothelial shear stress in the natural history of coronary atherosclerosis and vascular remodeling: molecular, cellular, and vascular behavior.J Am Coll Cardiol. 2007; 49:2379–2393. doi: 10.1016/j.jacc.2007.02.059.CrossrefMedlineGoogle Scholar
  • 24. Wentzel JJ, Kloet J, Andhyiswara I, Oomen JA, Schuurbiers JC, de Smet BJ, Post MJ, de Kleijn D, Pasterkamp G, Borst C, Slager CJ, Krams R. Shear-stress and wall-stress regulation of vascular remodeling after balloon angioplasty: effect of matrix metalloproteinase inhibition.Circulation. 2001; 104:91–96.LinkGoogle Scholar
  • 25. Cheng C, Tempel D, Oostlander A, Helderman F, Gijsen F, Wentzel J, van Haperen R, Haitsma DB, Serruys PW, van der Steen AF, de Crom R, Krams R. Rapamycin modulates the eNOS vs. shear stress relationship.Cardiovasc Res. 2008; 78:123–129. doi: 10.1093/cvr/cvm103.CrossrefMedlineGoogle Scholar
  • 26. Cheng C, van Haperen R, de Waard M, van Damme LC, Tempel D, Hanemaaijer L, van Cappellen GW, Bos J, Slager CJ, Duncker DJ, van der Steen AF, de Crom R, Krams R. Shear stress affects the intracellular distribution of eNOS: direct demonstration by a novel in vivo technique.Blood. 2005; 106:3691–3698. doi: 10.1182/blood-2005-06-2326.CrossrefMedlineGoogle Scholar
  • 27. Krams R, Cheng C, Helderman F, Verheye S, van Damme LC, Mousavi Gourabi B, Tempel D, Segers D, de Feyter P, Pasterkamp G, De Klein D, de Crom R, van der Steen AF, Serruys PW. Shear stress is associated with markers of plaque vulnerability and MMP-9 activity.EuroIntervention. 2006; 2:250–256.MedlineGoogle Scholar
  • 28. Krams R, Verheye S, van Damme LC, Tempel D, Mousavi Gourabi B, Boersma E, Kockx MM, Knaapen MW, Strijder C, van Langenhove G, Pasterkamp G, van der Steen AF, Serruys PW. In vivo temperature heterogeneity is associated with plaque regions of increased MMP-9 activity.Eur Heart J. 2005; 26:2200–2205. doi: 10.1093/eurheartj/ehi461.CrossrefMedlineGoogle Scholar
  • 29. Krams R, Wentzel JJ, Oomen JA, Vinke R, Schuurbiers JC, de Feyter PJ, Serruys PW, Slager CJ. Evaluation of endothelial shear stress and 3D geometry as factors determining the development of atherosclerosis and remodeling in human coronary arteries in vivo. Combining 3D reconstruction from angiography and IVUS (ANGUS) with computational fluid dynamics.Arterioscler Thromb Vasc Biol. 1997; 17:2061–2065.LinkGoogle Scholar
  • 30. Bourantas CV, Papafaklis MI, Garcia-Garcia HM, Farooq V, Diletti R, Muramatsu T, Zhang Y, Kalatzis FG, Naka KK, Fotiadis DI, Onuma Y, Michalis LK, Serruys PW. Short- and long-term implications of a bioresorbable vascular scaffold implantation on the local endothelial shear stress patterns.JACC Cardiovasc Interv. 2014; 7:100–101. doi: 10.1016/j.jcin.2013.01.139.CrossrefMedlineGoogle Scholar
  • 31. Bourantas CV, Papafaklis MI, Lakkas L, Sakellarios A, Onuma Y, Zhang YJ, Muramatsu T, Diletti R, Bizopoulos P, Kalatzis F, Naka KK, Fotiadis DI, Wang J, Garcia Garcia HM, Kimura T, Michalis LK, Serruys PW. Fusion of optical coherence tomographic and angiographic data for more accurate evaluation of the endothelial shear stress patterns and neointimal distribution after bioresorbable scaffold implantation: comparison with intravascular ultrasound-derived reconstructions.Int J Cardiovasc Imaging. 2014; 30:485–494. doi: 10.1007/s10554-014-0374-3.CrossrefMedlineGoogle Scholar
  • 32. Koskinas KC, Chatzizisis YS, Papafaklis MI, Coskun AU, Baker AB, Jarolim P, Antoniadis A, Edelman ER, Stone PH, Feldman CL. Synergistic effect of local endothelial shear stress and systemic hypercholesterolemia on coronary atherosclerotic plaque progression and composition in pigs.Int J Cardiol. 2013; 169:394–401. doi: 10.1016/j.ijcard.2013.10.021.CrossrefMedlineGoogle Scholar
  • 33. LaMack JA, Himburg HA, Zhang J, Friedman MH. Endothelial gene expression in regions of defined shear exposure in the porcine iliac arteries.Ann Biomed Eng. 2010; 38:2252–2262. doi: 10.1007/s10439-010-0030-6.CrossrefMedlineGoogle Scholar
  • 34. Khan OF, Sefton MV. Perfusion and characterization of an endothelial cell-seeded modular tissue engineered construct formed in a microfluidic remodeling chamber.Biomaterials. 2010; 31:8254–8261. doi: 10.1016/j.biomaterials.2010.07.041.CrossrefMedlineGoogle Scholar
  • 35. Kumar S, Sud N, Fonseca FV, Hou Y, Black SM. Shear stress stimulates nitric oxide signaling in pulmonary arterial endothelial cells via a reduction in catalase activity: role of protein kinase C delta.Am J Physiol Lung Cell Mol Physiol. 2010; 298:L105–L116. doi: 10.1152/ajplung.00290.2009.CrossrefMedlineGoogle Scholar
  • 36. Urso C, Caimi G. [Oxidative stress and endothelial dysfunction].Minerva Med. 2011; 102:59–77.MedlineGoogle Scholar
  • 37. Kuhlmann MT, Cuhlmann S, Hoppe I, Krams R, Evans PC, Strijkers GJ, Nicolay K, Hermann S, Schafers M. Implantation of a carotid cuff for triggering shear-stress induced atherosclerosis in mice.J Vis Exp. 2012; pii: 3308. doi: 10.3791/3308.Google Scholar
  • 38. Abela GS. Cholesterol crystals piercing the arterial plaque and intima trigger local and systemic inflammation.J Clin Lipidol. 2010; 4:156–164. doi: 10.1016/j.jacl.2010.03.003.CrossrefMedlineGoogle Scholar
  • 39. Davies PF. Hemodynamic shear stress and the endothelium in cardiovascular pathophysiology.Nat Clin Pract Cardiovasc Med. 2009; 6:16–26. doi: 10.1038/ncpcardio1397.CrossrefMedlineGoogle Scholar


Atherosclerosis is a multifocal lipid-driven inflammatory process. The precise environmental cues leading to plaque initiation, progression, and development of final lesion phenotype are not yet fully elucidated, but disturbed blood flow, which can be quantified by using metrics of shear stress, is thought to play a central role. In the current study, we evaluated whether inducing disturbed flow caused the development of advanced coronary plaques, including thin cap fibroatheroma, by implanting intracoronary shear-modifying stents in D374Y-PCSK9 hypercholesterolemic minipigs. We developed computational fluid dynamic models of local hemodynamics by using frequency-domain optical coherence tomography–derived coronary geometries and coregistered histology of the same vessel to these 3-dimensional reconstructions (3-dimensional histology). Our data support a causal role for lowered and multidirectional shear stress in the initiation of advanced coronary atherosclerotic plaques. Persistently lowered shear stress appears to be the principal flow disturbance needed for the formation of human-like thin cap fibroatheroma. This model, combined with frequency-domain optical coherence tomography–derived fluid dynamics and 3-dimensional histology, provides a new means of studying the biomechanics and mechanobiology of human-like advanced coronary plaques. Our data suggest that specific hemodynamic signatures may determine the development of specific coronary atherosclerotic plaque types. These observations provide the rationale for further exploring whether the metrics quantifying perturbation of normal (ie, nonatherogenic) flow, which evaluate changes in magnitude and direction of wall shear stress, may serve as biomarkers that predict the development of different types of advanced plaque, including those at increased risk of causing future clinical events.


eLetters should relate to an article recently published in the journal and are not a forum for providing unpublished data. Comments are reviewed for appropriate use of tone and language. Comments are not peer-reviewed. Acceptable comments are posted to the journal website only. Comments are not published in an issue and are not indexed in PubMed. Comments should be no longer than 500 words and will only be posted online. References are limited to 10. Authors of the article cited in the comment will be invited to reply, as appropriate.

Comments and feedback on AHA/ASA Scientific Statements and Guidelines should be directed to the AHA/ASA Manuscript Oversight Committee via its Correspondence page.