Early morning risk in elderly hypertension: Morning hypertension and prethrombotic state

Cardiovascular disease more frequently occurs early in the morning. Ambulatory blood pressure (BP), tissue-type plasminogen activator inhibitor-1 (PAI-1) and platelet activity exhibit a marked morning increase to trigger cardiovascular events. We studied the association between morning blood pressure (BP) surge and cerebrovascular disease in relation to prethrombotic state in elderly hypertensives. We studied stroke prognosis in 519 asymptomatic older hypertensives [mean age 72 years] in whom ambulatory BP monitoring was performed and silent cerebral infarct (SCI) was assessed using brain MRI, and who were followed prospectively for an average duration of 41 months. The morning BP surge (MBPS) was calculated as follows: the average of systolic BP during 2 hr after awakening - the average of systolic BP during 1 hr including the lowest sleep BP. Study 2. We measured formation of platelet aggregates of different sizes, hemostatic factors, and neurohumoral factors in the morning (9–10AM) and in the afternoon (4–5PM) in 60 elderly hypertensives. There was the threshold of the impact of MBPS on cerebrovascular disease. The highest group with MS≥55mmHg (Q10: MS group, n=53) had higher prevalence of SCIs (70% vs 48%,p=0.002) and higher stroke incidence (19% vs 7.3%,p=0.004) during the follow-up period than the other groups (Q1–9: non-MS group, MS<55mmHg,n=466). After they were matched for age and 24-hr BP level, the relative risk (RR) of MS group (vs non-MS group) remained significant (RR=2.7,p=0.04). Study 2. Spontaneous small-sized platelet aggregates (SPA) and all the hemostatic variables exhibited a greater thrombophilic tendency in the morning in relation to SCIs. The morning BP surge was positively correlated with the morning levels of SPA (r=0.62,p<0.0001), but not with the morning levels of the PAI-1 or prothrombin fragment 1+2, an indicator of hypercoagulability. A morning increase in plasma norepinephrine levels was significantly associated with an exaggerated morning BP surge and morning SPA (both,p<0.001). In older hypertensive patients, exaggerated morning BP surge is partly associated with the morning increase in platelet aggregation and is a risk factor for hypertensive cerebrovascular disease in relation to a morning increase in sympathetic activity.