T-Wave Alternans Predicts Arrhythmia-Free Survival in a SCD-HeFT Population: A Prospective Observational Study

Category:  09 Signal Average ECG/T-Wave Alternans

Presentation Time: Thursday, 1:30 p.m. - 1:45 p.m.

Daniel J. Cantillon, MD, Daniel P. Morin, MD, Eran S. Zacks, MD, Kenneth M. Stein, MD, Steven M. Markowitz, MD, Suneet Mittal, MD, Bindi K. Shah, MD, Matthew Janik, MD, Shaun Ageno, MD, Andreas C. Mauer, MD, Bruce B. Lerman, MD and Sei Iwai, MD. Cornell University Medical Center, New York, NY

Presentation Number: AB14-1

Keyword: T-wave alternans, Cardiomyopathies

Background: Microvolt T-wave alternans (TWA) has been proposed as a risk-stratifier in ischemic and non-ischemic cardiomyopathy (CM) pts. We prospectively evaluated the utility of TWA testing in predicting arrhythmia-free survival in this population.
Methods: We enrolled 268 consecutive pts (66 ± 11 yrs; 217 M [81%]) with ischemic or non-ischemic CM and EF ≤ 35% who underwent electrophysiologic testing and TWA testing and who were followed for ≥ 12 mos. TWA was performed by atrial pacing @ 550 ms or by treadmill testing, and interpreted using standard criteria. Positive and indeterminate results were grouped as non-negative. Pts were followed by telephone interview, hospital admission, clinic follow-up, and Social Security Death Index. The primary endpoint was arrhythmia-free (VT/VF) survival. Secondary endpoint was total mortality.
Results: 208 (78%) pts had ischemic CM and 60 (22%) had non-ischemic CM. The mean EF was 26 ± 7%. Pts were followed for 33 ± 14 months. TWA was negative in 78 pts (29%), and non-negative in 190 pts (71%). Life-table analysis demonstrated substantially better arrhythmia-free survival in TWA negative pts when compared with non-negative (p<0.001; see figure). There was no difference in ICD implant rates between TWA-negative and non-negative pts (65% vs 71%; p=0.84). Despite substantial ICD implant rates in this population, total mortality was high, albeit lower in the TWA-negative group (overall p = 0.05; 2 yr rate = 17 vs 28%). TWA had a negative predictive value (PV) of 77% for 2-yr arrhythmia-free survival and positive PV of 43% for 2-yr mortality.
Conclusions: Microvolt TWA testing is effective in predicting arrhythmia-free survival and all-cause mortality in a SCD-HeFT population. Although a negative TWA predicts event-free survival, the event rate in this group is sufficiently high to still warrant consideration of an ICD.