Prognostic Significance of T Wave Alternans
Prognostic Significance of T Wave Alternans
To evaluate whether T Wave Alternans can predict ventricular arrhythmias and sudden cardiac
 death (SCD) in a prospective epidemiologic natural history study.

 The prospective epidemiologic pilot study included 550 patients that had left ventricular
 dysfunction and no history of sustained ventricular arrhythmias. The primary hypothesis
 tested was whether there was an increased risk of having an arrhythmic event when T Wave
 Alternans was present in the patient. The secondary aims included comparing risk due to T
 Wave Alternans between the ischemic patients and non-ischemic patients and assessing whether
 T Wave Alternans remained an independent predictor of risk upon adjustment for other known
 risk factors for arrhythmic events such as ejection fraction, ventricular ectopy, NSVT,
 average NN interval, and RR interval variability.

 The study approach was a standard epidemiologic surveillance technique. The subject
 population consisted of individuals with Class I to III heart failure who will underwent a
 TWA and Holter monitor test and then were followed for up to two years or until arrhythmic
 events occured.
Sudden cardiac death accounts for approximately 400,000 deaths each year in the United States
 and remains a health problem of epidemic proportions. Most sudden cardiac deaths are caused
 by fatal ventricular arrhythmias. An effort aimed at the primary prevention of sudden cardiac
 death requires efficient identification of patients who are at high enough risk for having
 these arrhythmias to warrant aggressive prophylactic therapy. A number of recently completed,
 randomized clinical trials have demonstrated that an implantable cardiac defibrillator (ICD)
 can prevent sudden cardiac death in a highly selected group of high-risk patients. When these
 trials are viewed together, the only patients in whom the prophylactic implantation of an ICD
 has proven benefit are those patients identified by documented, spontaneous or inducible,
 sustained ventricular arrhythmias.

 Two randomized treatment trials (MADIT II, SCD-HEFT) tested the hypothesis that implantation
 of an ICD would reduce mortality in patients with congestive heart failure (CHF) and left
 ventricular dysfunction without any further risk tratification. However, the implications of
 these two trials-implantation of an ICD in every patient with CHF-were unlikely to be
 accepted either by the medical community or by health care payers. More efficient methods of
 risk stratification were necessary to identify those patients with CHF who were most likely
 to benefit from prophylactic treatment with an ICD.

 T Wave Alternans is a subtle every-other-beat variation in electrocardiographic T waves that
 is prognostic of patients at high risk for life-threatening cardiac arrhythmias and sudden
 cardiac death. It has recently been shown that T Wave Alternans (TWA) measured during
 exercise is strongly associated with inducible monomorphic CVT and with subsequent
 spontaneous arrhythmic events. This preliminary data suggest that TWA may be an efficient and
 non-invasive surrogate for electrophysiologic testing to screen patients who may be at
 high-risk for sudden cardiac death.
Inclusion Criteria

 1. Patients with left ventricular dusfunction

 2. Patients with non-ischemic cardiomyopathy

 Exclusion Criteria

 1. Patients not at high risk for sudden cardiac death (SCD)