PP.34.03

Abstract

Objective: Several features of ambulatory (ABPM) blood pressure (BP) have been explored as potential predictors of stroke. Some studies, limited among other factors by relying on a single, low reproducible 24 h ABPM per participant, use of arbitrarily fixed clock hours to defined awake and asleep spans, and/or analysis of the prognostic value of a single unadjusted ABPM-derived parameter, have concluded that elevated morning BP surge or increased BP variability might be significant markers of stroke. We evaluated the comparative prognostic value for stroke of clinic BP and multiple ABPM-derived characteristics among the participants in the Hygia Project, designed to evaluate prospectively CVD risk by ABPM in primary care centers of Northwest Spain. Design and method: This study involved 11255 subjects, 6028 men/5227 women, 58.9 ± 14.5 years of age, with baseline BP ranging from normotension to hypertension according to ABPM criteria, prospectively evaluated throughout a 4.0-year median follow-up. BP was measured at 20-min intervals from 07:00 to 23:00 h and every 30-min at night for 48 h. During monitoring, subjects maintained a diary listing the times of going to bed and awakening. Results: We documented 147 ischemic and 29 hemorrhagic strokes. When each ABPM-derived parameter was analyzed separately, the asleep systolic BP mean was the most significant predictor of stroke (adjusted hazard ratio 1.35; 95%CI [1.20–1.52] for each 1-SD increase; P < 0.001). A greater morning BP surge was significantly associated with lower, not higher, stroke risk (0.87 [0.76–0.99], P = 0.042). After adjustment by asleep BP, neither clinic BP nor any other ABPM-derived parameter, including awake and 48 h means, sleep-time relative BP decline, morning surge, and indices of awake, asleep and 24 h BP variability, was significantly associated with increased/decreased risk of stroke. Conclusions: Progressively elevated sleep-time systolic BP was the only significant and independent prognostic marker of stroke. Contrary to current believe, neither a greater morning BP surge, morning hypertension, or extreme-dipper BP patterning increased the risk of stroke after adjusting by asleep BP level. On the basis of the null prognostic value of clinic BP here corroborated, ABPM should be considered a clinical requirement for proper stroke risk stratification.