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Response to Do Extreme Dippers Have a Lower Cardiovascular Risk Than Dippers?

Originally publishedhttps://doi.org/10.1161/HYPERTENSIONAHA.112.202002Hypertension. 2012;60:e31–e32

We read with interest the letter by Sobiczewski and Wirtwein.1 We are aware of the potential relation between low levels of blood pressure (BP) at night and central nervous system ischemia. Sobiczewski and Wirtwein1 mention a study by Kario et al2 in which the prevalence of lacunae detected by MRI was 69% in a group of 16 subjects categorized as extreme dippers, 32% in a group of 38 dippers, and 63% in a group of 46 nondippers. Other reports suggest that such association may not apply to younger or mildly aged individuals. For example, in a study by Kohara et al,3 a J-shaped relation between nighttime BP and lacunar lesions by MRI was only evident in subjects aged >60 years but not in younger subjects. The mean age of our subjects at entry was 50.8 years. In a large cohort of individuals referred for ambulatory BP monitoring and aged 55 years at entry, the risk of mortality progressively increased from extreme dippers, dippers, nondippers, and reverse dippers.4

We have re-examined our data by forcing the absolute BP values at night and the percentage reduction in BP from day to night in the same multivariable model. After adjustment for age, sex, diabetes mellitus, cigarette smoking, total cholesterol, left ventricular hypertrophy by electrocardiography, and the estimated glomerular filtration rate, for each 16-mm Hg (ie, 1 SD) increase in nighttime BP, the risk of major cardiovascular disease (ie, composite pool of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, and hospitalization for heart failure)5 increased by 56% (95% CI, 35% to 80%), and the percentage reduction in BP from day to night did not achieve significance (P=0.443). The graphic development of such equation is shown in the Figure. The lines represent the midpoint values for each quartile of nighttime BP. The hazard ratio for the composite pool of major cardiovascular events markedly increased with nighttime BP, whereas the impact of the reduction in BP from day to night was negligible and not statistically significant. The overwhelming impact of the absolute nighttime BP on the BP changes from day to night emerged also in a meta-analysis by Fagard et al.6

Figure.

Figure. Hazard ratio for cardiovascular events at any level of blood pressure reduction from day to night for progressively higher levels of nighttime blood pressure. The lines represent the midpoint values for each quartile of nighttime blood pressure.

Sobiczewski and Wirtwein1 suggest that antihypertensive treatment could increase cardiovascular risk in extreme dippers as a result of excessive lowering of BP at night. They mention the study by Pierdomenico et al,7 but such citation is not fully appropriate in this context, because low nighttime BP values during treatment were associated with myocardial ischemia in that study,7 whereas, conversely, none of our subjects received antihypertensive treatment at the time of ambulatory BP monitoring. We re-examined our data5 regarding treatment at censoring or last contact before a cardiovascular event. Of 408 subjects classified as extreme dippers, 96 were untreated and 312 were treated with antihypertensive drugs. A major cardiovascular event occurred in 5 subjects in the former group and 20 subjects in the latter group (log-rank test, χ2=0.032; P=0.859). Thus, our data do not support the hypothesis that antihypertensive treatment worsens outcome in extreme dippers.

Paolo VerdecchiaStruttura Complessa di MedicinaOspedale di AssisiAssisi, ItalyGianpaolo ReboldiDipartimento di Medicina InternaUniversità di PerugiaPerugia, ItalyFabio AngeliSezione di CardiologiaPerugia, Italy

Footnotes

Letters to the Editor will be published, if suitable, as space permits. They should not exceed 1000 words (typed double-spaced) in length and may be subject to editing or abridgment.

References

  • 1. Sobiczewski W, Wirtwein M. Do extreme dippers have a lower cardiovascular risk than dippers?Hypertension. 2012; 60:e30.LinkGoogle Scholar
  • 2. Kario K, Matsuo T, Kobayashi H, Imiya M, Matsuo M, Shimada K. Nocturnal fall of blood pressure and silent cerebrovascular damage in elderly hypertensive patients: advanced silent cerebrovascular damage in extreme dippers.Hypertension. 1996; 27:130–135.LinkGoogle Scholar
  • 3. Kohara K, Igase M, Yinong J, Fukuoka T, Maguchi M, Okura T, Kitami Y, Hiwada K. Asymptomatic cerebrovascular damages in essential hypertension in the elderly.Am J Hypertens. 1997; 10:829–835.CrossrefMedlineGoogle Scholar
  • 4. Ben-Dov IZ, Kark JD, Ben-Ishay D, Mekler J, Ben-Arie L, Bursztyn M. Predictors of all-cause mortality in clinical ambulatory monitoring: unique aspects of blood pressure during sleep.Hypertension. 2007; 49:1235–1241.LinkGoogle Scholar
  • 5. Verdecchia P, Angeli F, Mazzotta G, Garofoli M, Ramundo E, Gentile G, Ambrosio G, Reboldi G. Day-night dip and early morning surge in blood pressure in hypertension: prognostic implications.Hypertension. 2012; 60:34–42.LinkGoogle Scholar
  • 6. Fagard RH, Celis H, Thijs L, Staessen JA, Clement DL, De Buyzere ML, De Bacquer DA. Daytime and nighttime blood pressure as predictors of death and cause-specific cardiovascular events in hypertension.Hypertension.2008; 51:55–61.LinkGoogle Scholar
  • 7. Pierdomenico SD, Bucci A, Costantini F, Lapenna D, Cuccurullo F, Mezzetti A. Circadian blood pressure changes and myocardial ischemia in hypertensive patients with coronary artery disease.J Am Coll Cardiol.1998; 31:1627–1634.CrossrefMedlineGoogle Scholar

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