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Therapy of Sustained Ventricular Arrhythmias With Amiodarone: Prediction of Efficacy With Serial Electrophysiologic Studies

The Texas Arrhythmia Institute, 6560 Fannin, Suite 620. Houston. TX 77030.

Udaya S. Swarna, MD

The Texas Arrhythmia Institute, 6560 Fannin, Suite 620. Houston. TX 77030.

Kwabena A. Boahene, MD

The Texas Arrhythmia Institute, 6560 Fannin, Suite 620. Houston. TX 77030.

Timothy K. Doyle, MD

The Texas Arrhythmia Institute, 6560 Fannin, Suite 620. Houston. TX 77030.

Antonio Pacifico, MD

The Texas Arrhythmia Institute, 6560 Fannin, Suite 620. Houston. TX 77030.

Background: Programmed electrical stimulation early during amiodarone therapy has poor prognostic capabilities; and persistent inducibility has been associated with a favorable outcome in a majority of patients. These observations result from studies that differed significantly in methodology.

Methods and Results: The authors prospectively enrolled 121 patients in a standardized amiodarone dosing protocol in which amiodarone was the only antiarrhythmic agent. Electrophysiologic testing was done after 2 and 6 weeks to determine noninducibility, predictive value, and the significance of drug-induced prolongation of tachycardia cycle length. The mean age of the patients in the study was 63.2 ± 11.5 years, and their ejection fraction was 32.8 ± 11.9%. Coronary artery disease was present in 103 (85%). At 2 weeks 17 patients (14%) were no longer inducible, whereas 101 patients (86%) remained inducible. Patients in these groups were similar in age and ejection fraction. During follow-up evaluation, recurrences (35% vs 24%; P =.44) and sudden death (12% vs 13.5%) were similar in the two groups. Thirty-five of 95 patients (32%) with sustained monomorphic ventricular tachycardia had more than 100 ms prolongation of their cycle length, which was hemodynamically well tolerated (partial response), but 60 did not (nonresponse). Patients with a partial response were older (66.5 vs 61.1 years; P =.02) and had longer QRS durations (143.2 vs 129.4 ms; P =.03). They also had increased recurrences (37% vs 17%; P =.01) and more sudden deaths (23% vs 8%; P =.02). At 6 weeks 11 of 76 patients studied were noninducible. They had a lower recurrence rate than those who remained inducible (8% vs 27%; P =.02) but a similar number of sudden deaths (8% vs 16%; P =.27). Thirty-two patients partially responded, and 31 patients did not respond. During follow-up examination these two groups had a similar number of recurrences (25% vs 29%; P =.76) and sudden deaths (16% vs 16%). Conclusions: Noninducibility at 2 or 6 weeks of amiodarone therapy did not identify patients at low risk of sudden death. In inducible patients, tachycardia cycle length prolongation, even when well tolerated, was not a marker for favorable outcome. Electrophysiologically guided therapy. therefore. offers little benefit over empiric amiodarone.

Conclusions: Noninducibility at 2 or 6 weeks of amiodarone therapy did not identify patients at low risk of sudden death. In inducible patients, tachycardia cycle length prolongation, even when well tolerated, was not a marker for favorable outcome. Electrophysiologically guided therapy. therefore. offers little benefit over empiric amiodarone.

Key Words: programmed electrical stimulation • predictive value. amiodarone.

Journal of Cardiovascular Pharmacology and Therapeutics, Vol. 1, No. 2, 123-132 (1996)
DOI: 10.1177/107424849600100206


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				B. N. Singh Amiodarone and Homogeneity of Ventricular Repolarization and Refractoriness Journal of Cardiovascular Pharmacology and Therapeutics, October 1, 1996; 1(4): 265 - 270. [PDF]

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