Adverse Effect of Nighttime Blood Pressure on the Outcome of Lacunar Infarct Patients

BACKGROUND AND PURPOSE: Antihypertensive therapy has dramatically reduced the incidence of stroke recurrence; however, recent studies have suggested that the excessive lowering of blood pressure (BP) could cause ischemic cerebral lesions. We conducted a prospective study using MRI and ambulatory blood pressure monitoring to elucidate the appropriate BP control level for the prevention of silent and symptomatic cerebral infarction. METHODS: We studied 105 patients with symptomatic lacunar infarcts who underWent repeated MRI and 24-hour BP monitoring in the period between the two MRI examinations. The patients were divided into five groups according to their outcome as follows: group 1, those who showed neither symptomatic episodes nor the development of new silent lesions detected by repeated MRI; group 2, those who only showed the development of silent lacunae; group 3, those who showed development of diffuse white matter lesions only; group 4, those who showed the development of both silent lacunae and diffuse white matter lesions; and group 5, those who showed symptomatic cerebrovascular disease. Groups 2 through 5 were then compared with group 1 with respect to the ambulatory BP values. RESULTS: The average follow-up period was 3.2 +/- 2.6 years (mean +/- SD). In all patients in group 4 and group 5, nighttime systolic BPs were significantly higher than in group 1 (both P<.01), and the magnitude of the nocturnal systolic BP dip and diastolic BP dip in group 4 and group 5 were significantly smaller than in group 1 (all P<.01). In patients who took antihypertensive agents, the 24-hour systolic and diastolic BPs and nighttime systolic and diastolic BPs in group 4 were significantly higher than in group 1 (P<.01, P<.01, P<.001, P<.01, respectively). The magnitude of the nocturnal systolic and diastolic BP dip in group 5 was significantly smaller than in group 1 (both P<.01). CONCLUSIONS: A high average ambulatory BP, especially nighttime BP, and a reduced nocturnal BP dip may have an adverse effect on the development of silent ischemic lesions and symptomatic stroke attack in patients with lacunar infarcts.