T-wave Alternans and Electrophysiology Study Offer Additive Risk Stratification Information in Ischemic Cardiomyopathy
Presentation Start/End Time:	Friday, May 11, 2007, 11:15 AM -11:29 AM
Location:	403
Author Block:	Daniel P. Morin, MD, MPH, Eran S. Zacks, MD, Andreas C. Mauer, MD, Shaun Ageno, MD, Matthew Janik, MD, Steven M. Markowitz, MD, Sei Iwai, MD, Bindi K. Shah, MD, Bruce B. Lerman, MD and Kenneth M. Stein, MD. Cornell University Medical Center, New York, NY
Introduction: T-wave alternans (TWA) and electrophysiology study (EPS) are used for risk stratification for sudden death. We hypothesized that TWA and EPS yield additive information. Methods: 386 pts (311 M, LVEF 29±8%) with CAD, NSVT, and LVEF < 40% underwent both TWA and EPS. TWA was determined with atrial pacing, and positive and indeterminate TWA were grouped together as nonnegative ("+"). Positive EPS was defined as monomorphic VT induced with up to triple ventricular extrastimuli (VES) or polymorphic VT or VF induced with up to double VES. Follow-up for the combined endpoint of VT, VF, or death was conducted via chart review, device interrogation, and query of the Social Security Death Index. Results: TWA was nonnegative in 259 (67%), and EPS was positive in 197 (51%). 144 (37%) had positive results in both TWA and EPS, while only 74 (19%) pts had negative results in both tests. 168 (44%) pts had incongruent results (115 TWA+/EPS- and 53 TWA-/EPS+). In univariate analysis, both TWA and EPS predicted events (HR 1.52, p=0.035 and HR 1.75, p=0.002). In multivariate analysis, both tests remained predictive (TWA: HR=2.20, p=0.02; EPS: HR=2.92, p<0.01) with a trend toward a multiplicative interaction between the two tests (p=0.07). Thus, the only lower-risk group consisted of those pts with negative results of both tests. Two-year event rates: TWA-/EPS- 11%, TWA+/EPS- 22%, TWA-/EPS+ 30%, TWA+/EPS+ 30%. Conclusions: In pts referred for EP testing due to ischemic cardiomyopathy and NSVT, both TWA and EPS stratify patients by risk for VT, VF, or death. The only lower-risk group consists of pts with negative results of both tests, while the other 3 groups had relatively high event rates. A screening strategy using both TWA and EPS in this population would be limited by the small number who screen negative in both tests, and by the nontrivial 2-year event rate in those pts.