Electrocardiographic repolarization-related variables as predictors of coronary heart disease death in the women's health initiative study

Background: We evaluated 25 repolarization-related ECG variables for the risk of coronary heart disease (CHD) death in 52 994 postmenopausal women from the Women's Health Initiative study. Methods and Results: Hazard ratios from Cox regression were computed for subgroups of women with and without cardiovascular disease (CVD). During the average follow-up of 16.9 years, 941 CHD deaths occurred. Based on electrophysiological considerations, 2 sets of ECG variables with low correlations were considered as candidates for independent predictors of CHD death: Set 1, θ(T_p|T_ref), the spatial angle between T peak (T_p) and normal T reference (T_ref) vectors; θ(T_init|T_term), the angle between the initial and terminal T vectors; STJ depression in V6 and rate-adjusted QT_p interval (QT_pa); and Set 2, TaVR and TV1 amplitudes, heart rate, and QRS duration. Strong independent predictors with over 2-fold increased risk for CHD death in women with and without CVD were θ(T_p|T_ref) >42° from Set 1 and TaVR amplitude >-100 μV from Set 2. The risk for these CHD death predictors remained significant after multivariable adjustment for demographic/clinical factors. Other significant predictors for CHD death in fully adjusted risk models were θ(T_init|T_term) >30°, TV1 >175 μV, and QRS duration >100 ms. Conclusions: θ(T_p|T_ref) angle and TaVR amplitude are associated with CHD mortality in postmenopausal women. The use of these measures to identify high-risk women for further diagnostic evaluation or more intense preventive intervention warrants further study.