T Wave Alternans in Congestive Heart Failure - TWA in CHF
The goal of the T Wave Alternans in Congestive Heart Failure (TWA in CHF) study was to determine if TWA is associated with an increased risk of having an arrhythmic event in patients with left ventricular (LV) dysfunction who have not yet had an arrhythmic event.
TWA is associated with an increased risk of having an arrhythmic event in patients with LV dysfunction who have not yet had an arrhythmic event.
Patients Screened: 590
Patients Enrolled: 542
NYHA Class: NYHA II (52%) and III (28%)
Mean Follow Up: Mean follow-up to date 12.2 months
Mean Patient Age: Mean age 56 years
Mean Ejection Fraction: Mean EF was 0.25 ± 0.9 and 61% of patients had an EF <30%.
EF ≤40% with no prior history of an arrhythmic event and age ≥18 years
Unstable coronary disease, New York Heart Association (NYHA) class IV CHF, and persistent atrial arrhythmias
Arrhythmic death and nonfatal cardiac arrest.
Patients with LV dysfunction who have not yet had an arrhythmic event underwent exercise testing with TWA and a 24-hour Holter recording.
The TWA test was positive in 30%, negative in 34%, and indeterminate in the remaining 36%. All-cause mortality at two years was higher in TWA positive patients versus TWA negative patients (hazard ratio [HR] 9.7, log rank p<0.01).
Among patients who were TWA negative and had an ejection fraction (EF) <30% (n=78), only one death occurred during follow-up. In a model adjusting for EF, positive TWA remained associated with mortality (HR 8.4, p<0.01).
Among patients with LV dysfunction who have not yet had an arrhythmic event, TWA was associated with an increased risk of death. TWA may provide additional risk stratification for patients with a low EF who, despite a low EF, may have low mortality and little benefit from an implantable cardioverter defibrillator (ICD).
Given the high cost of ICDs, risk stratification methods will be valuable in identifying an optimal patient population for use of the therapy. Further follow-up is needed to determine if the TWA remains associated with long-term follow-up. Additionally, results of the primary end point of arrhythmic death and nonfatal cardiac arrest are pending.
Presented at Late-Breaking Clinical Trials, ACC 2003.
Keywords: Follow-Up Studies, Heart Failure, Ventricular Dysfunction, Left, Defibrillators, Implantable, Exercise Test
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