Extreme-Dipper Profile, Increased Aortic Stiffness, and Impaired Subendocardial Viability in Hypertension

Abstract

Background: In treated hypertensives, extreme-dippers with stable coronary artery disease (CAD) exhibit more severe nighttime cardiac ischemia than dippers. After excluding confounding factors such as diabetes, CAD or chronic kidney disease (CKD), we assessed whether subendocardial viability, determined by the Buckberg index, was more significantly impaired in extreme-dippers than in dippers.

Methods: Two hundred thirteen consecutive treated hypertensives (156 dippers, 57 extreme-dippers), were included. After 24-hour ambulatory blood pressure (BP) monitoring, patients underwent radial applanation tonometry (with determination of: subendocardial viability ratio [SEVR], central augmentation index [AIx], and pulse pressure amplification [PPamp]), carotid-femoral pulse wave velocity (cfPWV) measurement, and cycle ergometer stress testing.

Results: Extreme-dippers showed higher cfPWV (8.99 ± 2.16 vs. 8.29 ± 1.69 m/s, P = 0.014), higher AIx (29.7 ± 9.4 vs. 26.4 ± 10.4%, P = 0.042), lower PPamp (1.22 ± 0.14 vs. 1.30 ± 0.15, P < 0.001), lower SEVR (146 ± 23% vs. 157 ± 26%, P = 0.007), and lower nighttime diastolic BP (DBP) (70 ± 9 vs. 75 ± 9 mm Hg, P < 0.001) than dippers. SEVR and cfPWV were inversely correlated. Among extreme-dippers, women exhibited lower SEVR (138 ± 21% vs. 161 ± 23%, P = 0.004), PPamp (1.16 ± 0.10 vs. 1.31 ± 0.15, P < 0.001), and nighttime DBP (67 ± 8 mm Hg vs. 72 ± 8 mm Hg, P = 0.017) than men.

Conclusions: Extreme-dipper treated hypertensives with no history of CAD, diabetes or CKD, present increased aortic stiffness and low PPamp. Furthermore, this is the first demonstration of the greater likelihood of these patients to exhibit impaired subendocardial viability compared to dippers. Extreme-dipper hypertensive patients, women in particular, may have a significantly higher risk of silent myocardial ischemia, thus justifying systematic screening.

Keywords: blood pressure; coronary microcirculation; extreme dippers; hypertension; subendocardial viability..