Dallas, TX

November 8-11, 1998

T-wave alternans (TWA) is a novel, noninvasive method proposed for the assessment of ventricular tachyarrhythmic risk. Whether amiodarone (Amio) therapy interacts with the presence of TWA is unknown. We evaluated TWA using submaximal bicycle exercise (target HR 105-110 BPM) in patients with a history of malignant ventricular tachyarrhythmias to assess the effect of Amio. A positive test was defined as the presence of sustained TWA with an onset of heart rate £ 110 BPM. Results: TWA testing was done in 44 patients (30 non-Amio; 14 Amio). There were no differences in age (58.0 ± 15.0 years; 63.2 ± 6.7 years; p = 0.2), LVEF (29.1 ± 15.3%; 34.4 ± 11.16%; p = 0.3) or underlying CAD (58.6%; 64.3%; p = 0.7) between the non-Amio and Amio groups, respectively. The incidence of indeterminate studies secondary to inadequate HR or excessive noise occurred in 8/30 (27%) non-Amio patients vs. 5/14 (36%) Amio patients, p = 0.5. In those with determinate studies, TWA (+) was observed in 14 of 22 patients in the non-Amio group (64%) but only in 1 of 9 patients in the Amio group (11%), p = 0.02 (2-sided Fisher’s exact test). The average total dose of Amio was 264 ± 252 grams. The single patient receiving Amio who was TWA (+) had received less than 30 grams total prior to performing TWA assessment. Conclusion: Amiodarone appears to decrease TWA in patients at high risk for ventricular tachyarrhythmias or patients receiving Amio have a lower prevalence of TWA+ than non-Amio patients. Whether this finding predicts the efficacy of amiodarone in preventing ventricular tachyarrhythmias and in overall survival is unknown.