Morning blood pressure surge, dipping, and risk of ischemic stroke in elderly patients treated for hypertension

BACKGROUND: The independent prognostic significance of morning surge (MS) in blood pressure (BP) is not yet clear. We investigated the association between MS in systolic BP (SBP) and risk of ischemic stroke in elderly patients treated for hypertension. METHODS: Occurrence of ischemic stroke was evaluated in 1,191 elderly patients treated for hypertension (aged 60-90 years). Patients were divided according to tertiles of MS in SBP in the population as a whole, dipping status, and group-specific tertiles of MS in SBP in dippers and nondippers. RESULTS: During follow-up (9.1±4.9 years, range 0.4-20 years), 139 ischemic strokes occurred. The event rate per 100 patient-years was 1.28. After adjustment for various covariates, Cox regression analysis showed that stroke risk was not significantly associated with tertiles of MS in SBP in the population as a whole. When nondippers and dippers were analyzed separately by group-specific tertiles of MS in SBP, stroke risk was not associated with MS in nondippers. Conversely, in dippers, stroke risk was significantly higher in the third tertile (>23mm Hg) of MS in SBP (hazard ratio, 2.08; 95% confidence interval, 1.03-4.23; P = 0.04). Additional analysis showed that stroke risk was significantly and similarly higher in dippers with MS >23mm Hg and in nondippers than in dippers with MS <23mm Hg. CONCLUSIONS: In elderly patients treated for hypertension, high MS in SBP predicts stroke in dippers but not in nondippers. Nondippers are at high stroke risk with or without MS >23mm Hg.