Association Between Ambulatory Systolic Blood Pressure During the Day and Asymptomatic Intracranial Arterial Stenosis

It is unclear at what time-window of the day blood pressure (BP) is most closely associated with cerebrovascular damage. In this cross-sectional study, we examined the strength of association between intracranial arterial stenosis (ICAS) and systolic BP (SBP) across different time-windows using 24-hour ambulatory BP monitoring in 757 consecutively recruited patients with hypertension. ICAS was diagnosed with computerized tomographic angiography in 127 (16.8%) patients, of whom 64 (50.4%) had stenosis ≥50% and 82 (64.6%) had ICAS in ≥2 vessels. Patients with ICAS (142 mm Hg), especially of multiple vessels (145 mm Hg), compared with patients without ICAS (126 mm Hg), had significantly (P<0.001) higher early morning (05:00-07:59 am) SBP. The differences remained significant (P≤0.015) after adjustment for cardiovascular risk factors and SBPs at other time-windows of the day. Multivariate regression analysis showed that consecutive 3-hourly mean SBPs during the day were significantly associated with ICAS (odds ratio for each 10-mm Hg increase, 1.28-1.38; P≤0.001). However, only mean SBP obtained between 05:00 am and 07:59 am remained significant for ICAS (odds ratio, 1.30; P=0.019) when all consecutive 3-hourly mean SBPs were forced into a single multivariate model. In conclusion, the present study showed a significant association between early morning SBP and asymptomatic ICAS in patients with hypertension after accounting for conventional cardiovascular risk factors. Our findings highlight the importance of morning SBP as a cardiovascular risk factor and should be validated in prospective studies.