The QT interval and risk of incident atrial fibrillation

BackgroundAbnormal atrial repolarization is important in the development of atrial fibrillation (AF), but no direct measurement is available in clinical medicine.ObjectiveTo determine whether the QT interval, a marker of ventricular repolarization, could be used to predict incident AF.MethodsWe examined a prolonged QT interval corrected by using the Framingham formula (QTFram) as a predictor of incident AF in the Atherosclerosis Risk in Communities (ARIC) study. The Cardiovascular Health Study (CHS) and Health, Aging, and Body Composition (ABC) study were used for validation. Secondary predictors included QT duration as a continuous variable, a short QT interval, and QT intervals corrected by using other formulas.ResultsAmong 14,538 ARIC study participants, a prolonged QTFram predicted a roughly 2-fold increased risk of AF (hazard ratio [HR] 2.05; 95% confidence interval [CI] 1.42–2.96; P < .001). No substantive attenuation was observed after adjustment for age, race, sex, study center, body mass index, hypertension, diabetes, coronary disease, and heart failure. The findings were validated in Cardiovascular Health Study and Health, Aging, and Body Composition study and were similar across various QT correction methods. Also in the ARIC study, each 10-ms increase in QTFram was associated with an increased unadjusted (HR 1.14; 95% CI 1.10–1.17; P < .001) and adjusted (HR 1.11; 95% CI 1.07–1.14; P < .001) risk of AF. Findings regarding a short QT interval were inconsistent across cohorts.ConclusionsA prolonged QT interval is associated with an increased risk of incident AF.