Objectives: To assess the influence of 24 h blood pressure (BP) levels on functional recovery 1 week after stroke and the effect of antihypertensive therapy on 24 h BP levels.
Design: Prospective study of patients admitted to hospital over 1 year with first in a lifetime stroke who underwent 24 h BP and casual measurements. Setting. Medical wards in a teaching hospital. Subjects. Of 160 patients, 72 patients admitted to hospital within 24 h of stroke onset were investigated. Patients with conditions and therapy that interfered with autonomic and sympathetic function were excluded. Interventions. All subjects underwent 24 h BP and casual recordings on admission to hospital and at day seven after stroke. The mean 24 h, day and night systolic BP (SBP) and diastolic BP (DBP) and their differences (nocturnal BP dip) were recorded. Patients were divided into three groups according to whether they were taking antihypertensive therapy during the first week: (i) no therapy, (ii) therapy continued after stroke, and (iii) new therapy introduced. Main outcome measures. Functional recovery (Rankin Scale 0-1) and neurological improvement [Scandinavian Stroke Scale (SSS) >/=3 points] by 1 week of stroke. Change in circadian 24 h BP over 1 week.
Results: For each 10 mmHg difference between day and night time DBP, the odds for making a complete recovery were 4.63 (95% CI: 1.57-13.7, P=0.01). For each 10 mmHg difference between day and night SBP, the odds for making an improvement in neurological status was 2.24 (95% CI: 1.16-4.32; P=0.016). Significant falls in 24 h DBP (P=0.01), daytime SBP (P=0.005) and mean arterial BP (MABP) (P=0.04) over 1 week were demonstrated in patients who had just commenced antihypertensive therapy (P=0.001).
Conclusion: An increase in day to night time BP change is favourable in short-term outcome after acute stroke. Significant falls in BP are more likely in patients started on antihypertensive therapy for the first time. Further research is required to understand the effects of circadian BP rhythm on stroke outcome.