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.