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

Abstract

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.