Abstract 187: U/T Wave Amplitude Ratio as an Indicator of Ventricular Arrhythmia Risk After Myocardial Infarction

Abstract

Objectives: This prospective study examined if abnormal repolarization presenting as increased U/T wave amplitude ratio predicts ventricular arrhythmias in patients with a recent myocardial infarction (MI) and moderate cardiac dysfunction. Methods and results: The study group (n = 126, 24 female) comprised patients with a recent MI and left ventricular ejection fraction (LVEF) < 50%. Mean age was 60 years and LVEF 40%. A 120-channel body surface potential mapping (BSPM) registration was performed at hospital discharge. After signal-averaging of 250-300 beats, T- and U waves were identified and their amplitudes computed with a custom made software. QRS duration was computed for comparison. The study endpoints were arrhythmic events (sudden cardiac death, sustained ventricular tachycardia or ventricular fibrillation), cardiac mortality, and all-cause mortality. During a mean follow-up of 51 months 22 patients (17.3%) died with 13 (10.3%) suffering cardiac death. Twelve patients (9.5%) had an arrhythmic event. Patients with arrhythmic event had significantly higher U/T maximum amplitude ratios (the ratio between the highest U and T waves in BSPM) compared to those without (0.222 ± 0.129 vs. 0.129 ± 0.085, p = 0.012). U/T maximum amplitude ratio was a significant predictor of arrhythmic events (log-rank 9.3, p = 0.002) and in multivariate analysis it showed predictive power independently of clinical variables including age, sex, LVEF, bundle branch block, and diabetes with the hazard ratio (HR) of 5.84. QRS duration also showed prediction with the HR of 1.04. A combination of the parameters further improved prediction with an area under the ROC curve of 0.80 ± 0.07 (p < 0.001). U/T maximum amplitude ratio did not predict cardiac or all-cause mortality. Conclusion: U/T wave amplitude ratio is a marker of ventricular arrhythmia propensity after MI. A combination of parameters describing repolarization and depolarization abnormalities further improves ventricular arrhythmia risk assessment.