Systolic blood pressure variability as a risk factor for stroke and cardiovascular mortality in the elderly hypertensive population.

OBJECTIVE To investigate whether baseline systolic blood pressure variability was a risk factor for stroke, cardiovascular mortality or cardiac events during the Syst-Eur trial. DESIGN The Syst-Eur study was a randomized, double-blind, placebo-controlled trial, powered to detect differences in stroke rate between participants on active antihypertensive treatment and placebo. Systolic blood pressure variability measurements were made on 744 participants at the start of the trial. Systolic blood pressure variability was calculated over three time frames: 24 h, daytime and night-time. The placebo and active treatment subgroups were analysed separately using an intention-to-treat principle, adjusting for confounding factors using a multiple Cox regression model. PARTICIPANTS An elderly hypertensive European population. MAIN OUTCOME MEASURES Stroke, cardiac events (fatal and non-fatal heart failure, fatal and non-fatal myocardial infarction and sudden death) and cardiovascular mortality (death attributed to stroke, heart failure, myocardial infarction, sudden death, pulmonary embolus, peripheral vascular disease and aortic dissection). RESULTS The risk of stroke increased by 80% (95% confidence interval: 17-176%) for every 5 mmHg increase in night-time systolic blood pressure variability in the placebo group. Risk of cardiovascular mortality and cardiac events was not significantly altered. Daytime variability readings did not predict outcome. Antihypertensive treatment did not affect systolic blood pressure variability over the median 4.4-year follow-up. CONCLUSION In the placebo group, but not the active treatment group, increased night-time systolic blood pressure variability on admission to the Syst-Eur trial was an independent risk factor for stroke during the trial.