Evaluation of Microvolt T Wave Alternans Test Result Concordance Over Time in the MASTER Trial
Presentation Start/End Time:	Monday, Mar 31, 2008, 10:00 AM -11:00 AM
Topic:	Clinical Electrophysiology--Ventricular Arrhythmias
Author Block:	Theodore Chow, Dean J. Kereiakes, John Onufer, Sinan Gursoy, Anastasios Manaris, Fei Lu, Brett J. Peterson, Mark L. Brown, Wenji Pu, David G. Benditt, on behalf of the MASTER Investigators, The Lindner Center at The Christ Hospital, Cincinnati, OH
Keywords:	Ventricular arrhythmia,Defibrillation, ventricular,Risk prediction
Background: Microvolt T-wave alternans (MTWA) results may change over time in individual patients. However, while the frequency of MTWA change in specific patient populations is not well characterized, such changes impact clinical utility and strategies for testing, including periodic re-testing. Methods: MASTER I and II are prospective trials conducted at 50 US centers in which patients with ischemic left ventricular (LV) dysfunction (ILVD) and LV ejection fraction ≤ 40% underwent annual MTWA testing. The protocol requested the same method of heart rate (HR) elevation be utilized for baseline and follow-up tests (treadmill exercise in 80%). All tests were interpreted by a Core Lab blinded to patient characteristics. MTWA indeterminates were excluded from analysis. Results: 628 patients had at least one follow-up MTWA test. Baseline testing was “+” in 346 (55%) and “-” in 282 (45%). For patients testing “-” at baseline, an estimated 30% tested “+” at their 1st annual test and after their 2nd annual test, 60% had tested “+” at least once. For patients testing “+” at baseline, an estimated 34% tested “-” at their 1st annual test and after their 2nd annual test, 61% had tested “-” at least once. Annual change in MTWA was more common if beta-blocker treatment status also changed (41% vs. 32%, p=0.04). Maximum negative HR during testing did not predict MTWA “-” to “+” conversion. However, MTWA “+” to “-” conversion was associated with a slightly higher onset HR for alternans (103.5 bpm vs. 101.1 bpm, p=0.01). Conclusions: Year-to-year change in MTWA is common in patients with ILVD. The time course and clinical significance of MTWA changes has important implications for patient testing, and requires further study.
Learning Objective 1:	Understand the concordance of microvolt T-wave alternans testing over time