Abstract 2113: T-Wave Alternans SCD HeFT Study: Primary Endpoint Analysis
The Sudden Cardiac Death in Heart Failure Trial (SCD HeFT) demonstrated that implantable defibrillators (ICD) decrease mortality compared with amiodarone or placebo, among patients (pts) with heart failure (NYHA II-III) and a reduced ejection fraction (≤ 35%). There is increasing interest in more refined risk stratification of SCD. In this regard, T-wave alternans (TWA) has emerged as a promising new measure of arrhythmia vulnerability.
Methods: This was a prospective study of 490 pts enrolled in SCD HeFT at 37 sites. Exercise TWA was interpreted by 2 blinded readers. The composite primary endpoint was SCD, sustained VT/VF or appropriate ICD discharge. All cause mortality was a secondary endpoint. Median follow-up was 35 months.
Results: This cohort was 76% male with median age of 59.6 yrs and EF of 25%. NYHA II CHF was present in 71% and 49% had ischemic heart disease. TWA was classified as positive (+) in 37%, Negative (−) in 22% and Indeterminate (Ind) in 41% of pts. Among ICD and placebo pts, there was no significant difference between event free survival among TWA + and − pts (HR=1.24, p=0.56, Figure⇓). Similarly, TWA non - (+ or Ind) did not differ from TWA - (HR=1.28, p=0.46). Finally, mortality did not differ significantly between TWA groups.
Conclusions: Indeterminate TWA results (41%) were frequently observed in this population, which may limit the utility of this test. In addition, TWA was not useful for risk stratifying arrhythmia vulnerability in SCD HeFT, regardless of test outcome.