A Comparison of T Wave Alternans, Signal Averaged Electrocardiography and Electrophysiology Study to Predict Arrhythmia Vulnerability
Michael R. Gold, Daniel M. Bloomfield, Kelley P. Anderson, David J. Wilber, Nabil El-Sherif, NA M. Estes III, William J. Groh, Elizabeth Kaufman, Richard J. Cohen, University of Maryland, Baltimore, MD
Background. T wave alternans (TWA) during pacing predicts arrhythmia vulnerability. To assess the utility of TWA measured noninvasively with exercise, we evaluated signal averaged ECG (SAECG), TWA and electrophysiology testing (EPS) in 201 patients in a multicenter trial.
Methods: Pts in sinus rhythm undergoing EPS were studied. TWA and SAECG were interpreted blindly by standard criteria. EPS + was defined as the induction of sustained monomorphic ventricular tachycardia (VT). An event was defined as death, sustained VT, cardiac arrest or appropriate defibrillator discharge.
Results: The pts were 63% male with a mean age of 56 + 15 years and a ejection fraction of 40 + 19%. Coronary artery disease was present in 48% of pts. TWA was positive in 19% of pts, negative in 55% and missing or indeterminate in 26%. SAECG was positive in 19%, negative in 54%, indeterminate or missing in 27%. EP was positive in 23%, negative in 52% and nonspecific (VF) or missing in 24%. Kaplan-Meier analysis revealed TWA and EPS as significant predictors of event-free survival (Table).
|
Events |
Relative Risk |
P value |
|
|
TWA |
12 |
11.0 |
<0.001 |
|
SAECG |
13 |
1.8 |
ns |
|
EPS |
17 |
3.1 |
<0.01 |
Conclusions.
We conclude that in this population, the noninvasive assessment of TWA with exercise is a highly significant predictor of events that is superior to SAECG and may be superior to EP.