Presentation Time:	11/15/2005 9:45:00 AM
Title:	Predictive Power of Microvolt T-Wave Alternans in Risk Stratifying MADIT-II and SCD-HeFT Eligible Patients
Keywords:	Arrhythmias,Heart failure,Ischemic heart disease,Cardiomyopathies
Author Block:	Paul Chan, University of Michigan, Ann Arbor, Ann Arbor, MI; Thedore Chow, Cheryl Bartone, Terri Booth, Edward J Schloss, Theordore Waller, Eugene Chung, Santosh Menon, Ohio Heart and Vascular Center, Cincinnati, OH; Brahmajee K Nallamothu, University of Michigan, Ann Arbor, Ann Arbor, MI; Dean Kereiakes, Ohio Heart and Vascular Center, Cincinnati, OH
Disclosure Block:	P. Chan, None; T. Chow, None; C. Bartone, None; T. Booth, None; E.J. Schloss, None; T. Waller, None; E. Chung, None; S. Menon, None; B.K. Nallamothu, None; D. Kereiakes, None.
Unlabeled/unapproved:	There are no unlabeled/unapproved uses of drugs or products.
Background: Implantable cardioverter-defibrillators (ICDs) reduce mortality in patients with left ventricular dysfunction, but their widespread use is expected to significantly raise healthcare costs. Although microvolt T-wave alternans (MTWA) has been proposed as an effective tool for identifying those high-risk patients most likely to benefit from ICDs, earlier studies have not controlled for baseline differences between MTWA negative and non-negative (positive and indeterminate) patients. Objective: To evaluate whether MTWA is an independent predictor of outcome in patients with ischemic and non-ischemic cardiomyopathy. Methods: We enrolled consecutive patients who met the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) criteria. All patients had baseline MTWA testing and were prospectively followed for a primary endpoint of all-cause mortality and appropriate ICD therapy. Stratified Cox proportional hazards analyses assessed whether MTWA remained an independent predictor of event-free survival, after adjusting for ICD status and baseline differences in demographic, clinical, medication treatment, and electrophysiologic variables (electrophysiologic study result, abnormal Holter, QRS>120ms). Results: A total of 768 patients with ischemic and 172 patients with non-ischemic cardiomyopathy criteria were identified with a mean follow-up of 18+10 months. Among the ischemic patients, 514 (67%) had a non-negative MTWA test. In stratified Cox proportional hazards analyses, a non-negative MTWA test remained an independent predictor of outcome [hazard ratio=2.45 (95%CI: 1.52, 3.96); p=0.0002]. This association persisted when only those ischemic patients meeting MADIT-II trial criteria were included [hazard ratio=2.36 (95%CI: 1.38, 4.05); p=0.002]. Among the non-ischemic patients, 95 (55%) had a non-negative MTWA test, which was also an independent predictor of outcome after multivariable adjustment [hazard ratio=4.73; (95%CI: 1.12, 20.03); p=0.04]. Conclusion: Microvolt T-wave alternans is a strong and independent predictor of mortality and appropriate ICD therapy among MADIT-II and SCD-HeFT eligible patients with either ischemic or non-ischemic cardiomyopathy.