Relation of T-wave Alternans to Left Ventricular Dyssynchrony in Patients with Coronary Heart Disease

Abstract

Purpose: Coronary heart disease (CHD) is associated with exaggerated repolarization dispersion and risk for cardiac arrest. We hypothesized that T-wave alternans (TWA) from the electrocardiogram, reflecting proarrhythmic repolarization dispersion, would increase with extent of ventricular dyssynchrony.

Method and Results: We studied 154 patients (pts, 69±9 years, 123 M) with documented CHD who underwent exercise treadmill testing and echocardiographic examination. TWA was analyzed continuously during treadmill testing in all standard precordial leads, and maximum TWA at heart rates <125 bpm was derived. Tissue Doppler imaging (TDI) was performed to measure interventricular dyssynchrony (Ts-RL: time difference between lateral and right free wall) and left ventricular (LV) intraventricular dyssynchrony (Ts-SD: standard deviation of time to peak systolic velocity of 12 LV segments; Ts-12: maximal difference in Ts between any 2 of 12 LV segments; Ts-6-basal: maximal difference in Ts between any 2 of 6 basal LV segments). 39 pts had high TWA >62μV (defined by >75 percentile of TWA). There were no significant differences in age, prevalence of myocardial infarction, hypertension and diabetes, and LV ejection fraction between high TWA and low TWA groups (all P>0.05). However, there were higher prevalence of female (33 vs. 16%, P=0.022) and body mass index (25.7±2.7 vs. 24.6±3.0kg/m2, P=0.040) in high TWA group than low TWA group. TDI showed significantly increased in Ts-RL (77.0±39.4 vs. 61.7±35.7ms, P =0.039), but not Ts-SD, Ts-12, and Ts-6-basal (all P>0.05) in pts with high TWA compared with low TWA. Furthermore, a modest but significant positive correlation was observed between TWA and Ts-RL. Multivariate analysis revealed that Ts-RL was an independent predictor for high TWA [Odd ratio: 1.022, 95% Confidence interval: 1.006–1.038, P =0.008].

Conclusions: Our results demonstrated that interventricular dyssynchrony in pts with CHD is associated with increase TWA, suggesting that interventricular dyssynchrony may contribute to proarrhythmic repolarization dispersion.