Repeated Assessment of Microvolt Level T-Wave Alternans in Patients With Acute Myocardial Infarction and Reduced LVEF: Results From a Long-Term Follow-up Study
Category:  09 Signal Average ECG/T-Wave Alternans
Presentation Time: Thursday, 3:45 p.m. - 4:45 p.m.
Thomas Klingenheben, MD, Christoph Haenisch, MD, Gerian C. Grönefeld, MD and Stefan H. Hohnloser, MD. J. W. Goethe University, Frankfurt, Germany
Presentation Number: P3-27
Poster Board Number: P3-27
Background: Microvolt level T-wave alternans (MTWA) is increasingly used for arrhythmia risk stratification. Particularly, its high negative predictive value points to a potential use as a risk stratifier in pts with ischemic cardiomyopathy. The value of MTWA assessed early after acute myocardial infarction (MI), however, seems to be limited. There are no data about the long-term course of MTWA in post-MI pts with reduced left ventricular ejection fraction (LVEF).
Method: Patients with a LVEF < 40% underwent MTWA assessment using exercise testing to increase heart rate (spectral method) within the first 10 days after an acute MI. After a median of 20 months, MTWA was re-assessed.
Results: Eighty-three patients were included in the study. At baseline, mean LVEF was 33+6% which increased to 40+10 % after 20 months (p<0.05). At baseline, 14 patients tested MTWA positive (17%), 41 (49%) negative, and 28 (33%) had an indeterminate test result. At follow-up, respective prevalences were 19(23%), 49 (59%), and 15 (18%) pts. Whereas at baseline a similar LVEF in MTWA negative and non-negative pts (34+5 vs 31+8 %; p=NS) was found, LVEF was significantly higher in MTWA-negative pts at follow-up compared to non-negative pts (42+8 vs 34+12 %;p<0.05). Whereas 25 pts (30%) fulfilled the MADIT-II criteria at baseline, this was the case in only 11 pts (13%; p<0.01) at 20 months. In such "MADIT-II type" pts, the proportion of MTWA-positive tests increased from 24% to 45%.
Conclusion: MTWA is evolving over time after an acute MI. An increase in LVEF is associated with a higher proportion of MTWA negative tests. These data support the use of MTWA in pts with persistent LV dysfunction rather than in unselected patients in the early post-MI time frame.