Morning blood pressure surge, morning platelet aggregation, and silent cerebral infarction in older Japanese hypertensive patients

OBJECTIVE: To examine whether or not the extent of morning blood pressure surge (MBPS), defined as a morning SBP increase from sleep SBP, is associated with that of platelet aggregation, coagulation/fibrinolytic activity, and silent cerebral infarction (SCI) in older hypertensive patients. METHODS: Sixty hypertensive patients aged at least 60 years (mean age 70.6 years; 40% men) underwent measurement of morning spontaneous small-sized platelet aggregation (SPA) detected by a light scattering intensity method, measurement of circulatory levels of von-Willebrand factor (vWF), noradrenalin, and plasma renin activity (PRA), and brain MRI. RESULTS: The extent of MBPS, but not 24-h SBP, was associated with circulatory levels of noradrenalin, PRA, vWF, and spontaneous SPA (all P < 0.05); the association between MBPS and spontaneous SPA remained significant even after adjustment for significant covariates (P < 0.001). The patients with multiple (more than three per person) SCIs had a significantly greater extent of MBPS (43.3 vs. 31.8 mmHg), morning spontaneous SPA (20 471.9 vs. 4850.9 × 10 × 2 mV counts 10 min), and higher circulatory vWF (196.6 vs. 150.1%) compared with those without it (all P < 0.01). On multiple regression analysis, the odds ratio for multiple SCIs with a +1 SD increase of MBPS was 2.0, that of morning spontaneous SPA was 3.0, and that of circulatory morning vWF level was 3.3 (all P < 0.05). When MBPS increase and either platelet aggregation or vWF increases were entered into the same model, the latter parameters, but not the MBPS, were associated with multiple SCIs (both P < 0.05). CONCLUSION: The extent of MBPS was associated with increased activity of morning platelet aggregation in older hypertensive patients.