Simultaneous Assessment of T-Wave Alternans and Heart Rate Turbulence on Holter Electrocardiograms as Predictors for Serious Cardiac Events in Patients After Myocardial Infarction

Abstract

T-wave alternans based on the modified moving average method (MMA-TWA) and heart rate turbulence (HRT) have been introduced as predictors for cardiac mortality. In this study, we simultaneously recorded MMA-TWA and HRT in patients after myocardial infarction (MI) and designed a prospective observational study. We prospectively enrolled 313 consecutive post-MI patients (age 70 ± 12 years, 232 men). The MMA-TWA and HRT were simultaneously measured using algorithms based on 24-h Holter ECG monitoring during daily activity. MMA-TWA was determined positive when the maximal voltage was >64 µV, and HRT was determined positive when both turbulence onset and turbulence slope were abnormal. The endpoint was defined as overall cardiac mortality and fatal arrhythmic events. MMA-TWA was positive in 14 patients (4.4%) and HRT was positive in 61 patients (19.5%). During follow-up of 1,190 ± 441 days, 28 patients (9%) reached the endpoint, including 12 patients with fatal arrhythmic events. Both MMA-TWA and HRT were significant predictors for the endpoint. On multivariate analysis, HRT had the most significant value, with a hazard ratio (HR) of 5.7 (P=0.0008). When focused on fatal arrhythmic events including sudden cardiac death, MMA-TWA had the most significant value (HR 5.8, P=0.0072). The present study revealed that both MMA-TWA and HRT were significant predictors. MMA-TWA is more associated with arrhythmic events than cardiac mortality in post-MI patients.