Relative Predictive Value of T Wave Alternans and Left Ventricular Ejection Fraction for Death and Sustained Ventricular Arrhythmias in Patients with Left Ventricular Dysfunction
Category:  09 Signal Average ECG/T-Wave Alternans
Presentation Time: Friday, 8:30 a.m. - 8:45 a.m.
J. Thomas Bigger, MD, Michael K. Parides, PhD, Richard C. Steinman, BA, Pearila B. Namerow, PhD, Daniel M. Bloomfield, MD, for the TWA in CHF Investigators. Columbia University Medical Center, New York, NY
Presentation Number: AB27-2
Left ventricular ejection fraction (LVEF) is considered the “gold standard” for predicting risk in heart disease. We conducted a prospective longitudinal study to evaluate the relative predictive value of LVEF and T wave alternans (TWA) alone or jointly in patients with LVEF <0.41.
Methods: Patients with ischemic (IHD) or non- ischemic (N-IHD) heart disease were eligible if they had LVEF <0.41, sinus rhythm, NYHA class I-III, and no atrial fibrillation or history of sustained ventricular arrhythmias (SVA). All patients had a TWA exercise test and were followed for up to two years (average 20 months). Our composite endpoint included death of any cause and non-fatal SVA. We used Cox regression to estimate the univariate and multivariate hazard ratios (HR) relating LVEF and/or TWA to death/ SVA and to test for an interaction between LVEF and TWA.
Results: We studied 549 patients: 49% had IHD, 74% had LVEF <0.31 (average 0.25), 66% had an abnormal TWA test; and 51 experienced an endpoint (40 deaths, 11 SVA). TWA and LVEF were only weakly associated (odds ratio = 1.25, 95% CI 0.84-1.85). The actuarial 2-year event rate was 11.4%. The univariate hazard (HR) for death/ SVA was 1.8 (95% CI 0.88-3.73) for LVEF <0.31 vs ≥0.31 and 6.5 (95% CI 2.35-18.11) for TWA abnormal vs normal. In multivariate Cox models, TWA added predictive value to LVEF, but LVEF did not add significant predictive value to TWA; no significant interaction was found. The multivariate HR when LVEF and TWA were both in a Cox model were 1.7 (95% CI 0.84-3.53) and 6.4 (95% CI 2.31-17.79) respectively. The false negative rate was 6.3% for LVEF and 2.1% for TWA.
Conclusion: In both IHD and N-IHD, TWA was a significantly better univariate and multivariate predictor of death and SVA than LVEF. TWA also had a substantially lower false negative rate than LVEF. Moreover, TWA added substantial predictive value to LVEF <0.31; the converse was not true. Thus, TWA is a better predictor of death/SVA than LVEF among patients with LVEF <0.41.