Blood pressure reduction and secondary prevention of stroke and other vascular events: a systematic review.

BACKGROUND: High blood pressure is a risk factor for stroke recurrence. We assessed the effectiveness of lowering blood pressure in preventing recurrent vascular events in patients with previous stroke or transient ischemic attack. SUMMARY OF REVIEW: We performed a systematic review and meta-regression of completed randomized controlled trials that investigated the effect of lowering blood pressure on recurrent vascular events in patients with prior ischemic or hemorrhagic stroke or transient ischemic attack. Trials were identified from searches of 3 electronic databases (Cochrane Library, EMBASE, MEDLINE). Seven randomized controlled trials, with 8 comparison groups, were included. Lowering blood pressure or treating hypertension with a variety of antihypertensive agents reduced stroke (odds ratio [OR], 0.76; 95% CI, 0.63 to 0.92), nonfatal stroke (OR, 0.79; 95% CI, 0.65 to 0.95), myocardial infarction (OR, 0.79; 95% CI, 0.63 to 0.98), and total vascular events (OR, 0.79; 95% CI, 0.66 to 0.95). No effect was seen on vascular or all-cause mortality. Heterogeneity was present for several outcomes and was partly related to the class of antihypertensive drugs used; angiotensin-converting enzyme inhibitors and diuretics separately, and especially together, reduced vascular events, while beta-receptor antagonists had no discernable effect. The reduction in stroke was related to the difference in systolic blood pressure between treatment and control groups (P=0.002).
CONCLUSIONS: Evidence from randomized controlled trials supports the use of antihypertensive agents in lowering blood pressure for the prevention of vascular events in patients with previous stroke or transient ischemic attack. Vascular prevention is associated positively with the magnitude by which blood pressure is reduced.