Can Ambulatory ECG-Based T-Wave Alternans and Heart Rate Turbulence Predict Postoperative Arrhythmic Events in Patients Undergoing Coronary Artery Bypass Surgery?

Abstract

Methods and Results: We assessed prospectively whether T-wave alternans (TWA) and heart rate turbulence (HRT) from ambulatory electrocardiogram (AECG) predict postoperative in-hospital arrhythmic events in consecutive 106 patients (64±10 years old, M:F=80:26) who underwent coronary artery bypass graft (CABG) surgery. Patients with atrial fibrillation (AF) or ventricular paced rhythm were excluded. The highest TWA values from the 3 AECG channels corresponding to leads V1, V3, and V5 were averaged. Impaired HRT was defined by HRT slope ≤2.5 or HRT onset >0% as previous studies. Postoperative ventricular arrhythmic events were more frequently noted in patients with higher HRT value (>median, 53 µV) than the other patients (13/56 [23%] versus 4/50 [8%], P=0.03). Significantly higher proportion of patients showing impaired HRT developed postoperative new-onset AF (47% versus 23%, P=0.029). The presence of higher HRT value and impaired HRT were independently associated with ventricular arrhythmia (OR=3.54, 95%CI=1.01–12.4, P=0.049) and new-onset AF (OR=7.78, 95%CI=1.23–49.4, P=0.030), respectively, even after adjusting for relevant parameters. Conclusion: Abnormal TWA and HRT parameters, a marker for disturbance in cardiac repolarization and autonomic regulation, could be useful risk-stratification tools for predicting postoperative in-hospital ventricular arrhythmia and new-onset atrial fibrillation.