Is Isolated Nocturnal Hypertension a Novel Clinical Entity? Findings From a Chinese Population Study

Y. Li1， J.A. Staessen2， L. Lu1， G.L. Wang1， J.G. Wang1
1 Ruijin Hospital， Shanghai Jiaotong University School of Medicine， China
2 Studies Coordinating Centre， Department of Cardiovascular Diseases， University of Leuven， Belgium

Objectives: We previously reported that normotensive Chinese had higher nighttime diastolic pressure (BP) compared to non-Chinese. We therefore studied the prevalence and characteristics of isolated nocturnal hypertension (HT) and its association with arterial stiffness， an intermediate sign of target organ damage.

Methods: We recorded ambulatory BP， the central (CAI) and peripheral (PAI) systolic augmentation indexes， the ambulatory arterial stiffness index (AASI)， and brachial-ankle pulse wave velocity (baPWV) in 677 Chinese enrolled in the JingNing population study(53.6% women; mean age，47.6 years).

Results: Prevalence was 10.9% for isolated nocturnal HT (≥120/70mmHg from 22:00h to 04:00h)， 4.9% for isolated daytime HT (≥135/85mmHg from 08:00h to 18:00h)， and 38.4% for day-night HT. Patients with isolated nocturnal HT， compared to subjects with ambulatory normotension (45.8%)， were older (53.7 vs. 40.7 years)， more often reported alcohol intake (68.9% vs. 51.0%)， had faster nighttime pulse rate (62.8 vs. 60.7 beat/min)， higher serum cholesterol (5.12 vs. 4.77 mmol/L) and blood glucose(4.84 vs. 4.38 mmol/L)， similar to patients with isolated daytime HT or day-night HT， patients with isolated nocturnal HT had higher indexes of arterial stiffness (P<0.05) than subjects with ambulatory normotension (CAI， 140% vs. 134% ; PAI， 82.6% vs. 76.5%; AASI ，0.40 vs. 0.35 units; baPWV， 16.2 vs. 14.7m/s). Of 74 patients with isolated nocturnal HT， only 4 (5.4%) had hypertension on conventional office BP measurement(≥140/90 mm Hg).
Conclusion: Isolated nocturnal HT can only be diagnosed by ambulatory BP monitoring， is prevalent among Chinese， and is associated with increased arterial stiffness.