Prognostic Value of Microvolt T Wave Alternans In Patients with Left
Ventricular Systolic Dysfunction: A Meta-Analysis.
Category: 09 Signal Average ECG/T-Wave Alternans
Presentation Time: Thursday, 10:15 a.m. - 11:15 a.m.
Manish Undavia, MD, Vithaya Chaithiraphan, MD, Sonal Jani, MD, Ramesh M. Gowda,
MD, Paul Schweitzer, MD and David L. Brown, MD. Beth Israel Medical Center, New
York, NY, Stony Brook University School of Medicine, NY
Presentation Number: P2-29
Poster Board Number: P2-29
Background: Ventricular arrhythmias are the most common cause of sudden
cardiac death (SCD) in patients with left ventricular systolic dysfunction.
Despite significant advances in the management of left ventricular dysfunction
and prevention of SCD, identification of high-risk patients remains
challenging. Microvolt T wave alternans (MTWA) is a novel technique that has
shown promise as a prognostic tool in recent studies. However, these studies
have been limited by small sample sizes.
Methods: We performed a meta-analysis of all published studies
evaluating the utility of MTWA in predicting the outcomes of patients with left
ventricular systolic dysfunction. MTWA was defined as abnormal if the results
were either positive or indeterminate. A comprehensive Medline search identified
8 trials that met our prespecified criteria. The primary endpoint of interest
was as a composite of death, sustained ventricular tachycardia or ventricular
fibrillation. The odds ratios (OR) and the 95 % confidence interval (CI) of the
individual trials were pooled using a random effects model. A separate
meta-analysis was performed of the 4 studies that included only patients with
non-ischemic cardiomyopathy.
Results: Of the 1012 patients, an abnormal MTWA was present in 71 % of
the patients. The mean left ventricular ejection fraction ranged from 23 % to
41%. The mean follow-up period ranged from 13 to 52 months. A history of
coronary artery disease was present in 41 % of patients. The primary endpoint
occurred in 20.3 % of patients with an abnormal MTWA as compared to 3.8 % of
patients with a normal MTWA (OR: 4.1, 95% CI 2.02-8.31, P<0.001). Of the 538
patients with non-ischemic cardiomyopathy, an abnormal MTWA was present in 71 %
of the patients. An abnormal MTWA was associated with a significantly increased
risk of an adverse event (OR: 2.38; 95% CI 1.17-4.84, P=0.017).
Conclusion: An abnormal MTWA appears to be a powerful prognostic marker
of serious cardiac events in patients with left ventricular systolic
dysfunction. Its high predictive value is consistent across a wide spectrum of
patients with cardiomyopathy including those with non-ischemic etiologies.