Is T Wave Alternans a Predictor of Reversible Left Ventricular Dysfunction?
Category:  09 Signal Average ECG/T-Wave Alternans
Presentation Time: Thursday, 3:45 p.m. - 4:45 p.m.
Alberto Diaz, MD, Karen Kutoloski, DO, Mary Dettmer, RN, BSN and Ottorino Costantini, MD. MetroHealth Campus, Case Western Reserve University, Cleveland, OH
Presentation Number: P3-26
Poster Board Number: P3-26
Background: Recent clinical trials have suggested that prophylactic ICD therapy can be guided by a reduced ejection fraction (EF) alone. However, in cardiomyopathy (CM) patients, EF can improve over time, especially following interventions such as cardiac rehabilitation. Presently, it is not known if improvement in EF is paralleled by diminished risk in sudden cardiac death (SCD). Since T-wave alternans (TWA) is a sensitive marker of susceptibility to SCD in CM patients, we hypothesized that in patients undergoing a cardiac rehabilitation exercise training program, favorable mechanical remodeling (i.e. improvement in EF) will result in favorable electrical remodeling (i.e. resolution of TWA). Methods: 24 consecutive patients with CM (EF ≤ .40) completed a 36 week cardiac rehabilitation exercise training program. All patients underwent an echocardiogram and a TWA exercise test at baseline and again at completion of the program. EF and TWA were interpreted by readers blinded to the patients’ clinical history, outcomes, and to each other's readings. Results: Mean age was 54±12 years old, with 58% males, and 71% of patients having ischemic cardiomyopathy. In the whole group, mean EF improved from .26 ± .08. at baseline to .42 ± .15 following the rehabilitation program (p=0.0001). In contrast, TWA largely remained unchanged. At baseline, TWA tests were abnormal (positive or indeterminate) in 42% of patients (n=10) . 80% remained abnormal at the end of the program. At baseline, TWA tests were normal in 58% of patients (n=14). 86% remained normal at the end of the program. Remarkably, there was no improvement in EF in patients with an abnormal baseline TWA test (.26 ± .08 vs .31± .11 p=NS), whereas patients with a normal TWA had a significant improvement in EF (.26± .08 vs .47± .15 p= 0.0003). Conclusions: These data suggest that vulnerability to SCD remains unchanged after cardiac rehabilitation. A normal TWA test identified patients whose EF will improve following cardiac rehabilitation. These patients may have low risk of SCD and may not benefit from ICD implant. Surprisingly, these data also suggest that the presence of TWA is a marker for irreversible structural left ventricular remodeling.