Abstract 15550: Heart Rate Corrected QT Interval is an Independent Predictor of All-Cause Mortality in a Diabetic Population - The Diabetes Heart Study
BACKGROUND: Diabetes mellitus is a major risk factor for cardiovascular events and death. However, not all diabetics carry similar risk providing an opportunity for better risk prediction in this population. QT interval is associated with all-cause and cardiovascular mortality in the general population but this association remains inconsistent in diabetic populations. We assessed the association of QT interval with all-cause mortality in the Diabetes Heart Study.
METHODS: We studied 1020 participants with diabetes (83% Caucasians, 55% women, mean age: 61 years) who were free of atrial fibrillation, major ventricular conduction defects and antiarrhythmic therapy at baseline. QT duration was automatically calculated from a 12-lead electrocardiogram (ECG) recorded by standardized methods. Following AHA/ACC recommendations, a linear regression function was used to correct the QT for heart rate. Mortality risk was estimated per 1-SD increase in heart rate corrected QT. Cox proportional hazard analysis was used to examine the association between heart rate corrected QT and all-cause mortality after adjustment for potential confounders. For comparability with previous studies, we also corrected QT for heart rate using Bazett’s formula (QTc). RESULTS: Mean (SD) unadjusted QT duration, heart rate, and QTc (Bazett) were 390 (30) ms, 70 (12) beats/min, 420 (20) ms respectively. After a median follow up of 8.5 years (maximum 13.9), 204 died. In a multivariate model adjusted for age, ethnicity, gender, hypertension, body mass index, diabetes duration, current smoking, total cholesterol, triglyceride, estimated GFR, and baseline cardiovascular disease, 1-SD increase in heart rate corrected QT was associated with a 28% higher risk for all-cause mortality [HR (95%CI): 1.28 (1.01-1.61), p=0.0375]. In a similar model, 1-SD increase in QTc (Bazett) was associated with a 22% higher risk for all-cause mortality [1.22 (1.06-1.40), p=0.0046]. No significant interactions by sex or ethnicity were detected. CONCLUSION: Heart rate corrected QT is an independent predictor of all-cause mortality in diabetic population suggesting that important additional prognostic information is available from this simple ECG measure.
- © 2012 by American Heart Association, Inc.