Control of hypertension and risk of stroke recurrence

Abstract

Background and purpose: We investigated whether low blood pressure increases the risk of stroke recurrence.

Methods: A cohort of 662 patients, obtaining care at the 8 acute care hospitals serving the Lehigh Valley in Pennsylvania, was enrolled within 1 month of an initial stroke and was followed twice annually for up to 4 years. Cox proportional hazard models were developed to examine the relationship between risk of recurrent stroke and blood pressure, controlling for other significant risk factors. Our analyses investigated both lowest follow-up and average follow-up blood pressures as predictors of stroke recurrence.

Results: There were 52 recurrent strokes among the 535 patients (mean age, 71 years; 51% men) with follow-up blood pressure. The risk ratio for stroke recurrence for diastolic blood pressure > or =80 mm Hg compared with <80 mm Hg was 2.4 (95% CI, 1.38 to 4.27) and for systolic blood pressure > or =140 mm Hg compared with <140 mm Hg was also 2.4 (95% CI, 1.39 to 4.15). For isolated systolic blood pressure (>140/<90 mm Hg), the risk ratio was 2.2 (95% CI, 1.23 to 3.79) relative to <140/<90 mm Hg. Using the Cox model, we also showed that patients who had at least 1 measured diastolic blood pressure <80 mm Hg during follow-up had a reduced risk of stroke recurrence compared with those with diastolic blood pressures 80 to 90 mm Hg (0.4 versus 1.0; 95% CI, 0.21 to 0.88) even after controlling for the possible confounding factors of hypertension and atrial fibrillation on ECG. Myocardial infarction on ECG, history of transient ischemic attack, and diabetes mellitus were not significant predictors of increased risk of recurrent stroke.

Conclusions: Our results imply that "lower is better" for blood pressure control as a goal in reducing stroke recurrence risk.