Background and purpose: Increased visit-to-visit variability in blood pressure (BP) is a powerful risk factor for stroke, but the mechanism is uncertain. We hypothesized that BP variability might affect the risk of new atrial fibrillation (AF).
Methods: We did a systematic review of large randomized controlled trials reporting new-onset AF by treatment allocation, excluding studies in heart failure and acute myocardial infarction. Estimates of the risk of new AF by treatment allocation were related to effects of treatment on group variability in BP.
Results: Of 94 eligible randomized controlled trials, 14 reported rates of new AF. Although there was considerable heterogeneity between trials in effects of treatment on variance ratio (P<0.0001), lower variance ratio was unrelated to new-onset AF either on meta-analysis (OR=1.02; 95% CI 0.90 to 1.15; 125 878 patients; 13 comparisons) or on metaregression (log OR versus log variance ratio of systolic blood pressure r(2)=0.109, P=0.270). Angiotensin receptor blockers tended to reduce new-onset AF (OR 0.85; 95% CI 0.71 to 1.01; P=0.067; 4 trials; 47 482 patients) with significant reductions in 2 individual trials but had no consistent reduction on variability in BP.
Conclusions: Effects of randomized treatment on variability in BP are unrelated to risk of new-onset AF, suggesting that other mechanisms account for the link between variability and stroke risk. However, a lower incidence of AF in patients randomized to angiotensin receptor blockers may explain reductions in stroke risk in some trials.