Premature Cardiac Contractions and Risk of Incident Ischemic Stroke

BACKGROUND: The etiologies of ischemic stroke remain undetermined in 15% to 40% of patients. Apart from atrial fibrillation, other arrhythmias are less well-characterized as risk factors. Premature cardiac contractions are known to confer long-term cardiovascular risks, like myocardial infarction. Ischemic stroke as cardiovascular risk outcome remains a topic of interest. We examined the prospective relationships in the Atherosclerosis Risk in Communities (ARIC) study, to determine whether premature atrial (PAC) or ventricular (PVC) contractions are associated with increased risk for incident ischemic stroke. METHODS AND RESULTS: We analyzed 14 493 baseline stroke-free middle-aged individuals in the ARIC public-use data. The presence of PAC or PVC at baseline was assessed from 2-minute electrocardiogram. A physician-panel confirmed and classified all stroke cases. Average follow-up time was 13 years. Proportional hazards models assessed associations between premature contractions and incident stroke. PACs and PVCs were identified in 717 (4.9%) and 793 (5.5%) participants, respectively. In all, 509(3.5%) participants developed ischemic stroke. The hazard ratio (HR) (95% confidence interval [CI]) associated with PVC was 1.77 (1.30, 2.41), attenuated to 1.25 (0.91, 1.71) after adjusting for baseline stroke risk factors. The interaction between PVC and baseline hypertension was marginally significant (P=0.08). Among normotensives, having PVCs was associated with nearly 2-fold increase in the rate of incident ischemic stroke (HR 1.69; 95% CI 1.02, 2.78), adjusting for stroke risk factors. The adjusted risk of ischemic stroke associated with PACs was 1.30 (95% CI 0.92, 1.83). CONCLUSIONS: Presence of PVCs may indicate an increased risk of ischemic stroke, especially in normotensives. This risk approximates risk of stroke from being black, male, or obese in normotensives from this cohort.