What is the clinical evidence from this study?

Study design: Observational. Population: Ventricular tachycardia or supraventricular tachycardia (n=11). Intervention: Oral amiodarone vs. Baseline (before treatment). Primary outcome: Retrograde conduction (S2H2 interval) and refractoriness of the His-Purkinje system.

June 1, 1984Open Access

Effect of amiodarone on retrograde conduction and refractoriness of the His-Purkinje system in man.

CRC.A. ReddyCleveland Clinic CKC S KuoRutgers, The State University of New Jersey

Key Result

Long-term oral amiodarone prolonged the HV interval in 7 of 11 patients and significantly increased the refractory periods of the His-Purkinje system compared to baseline.

Study Design

Type

Observational (n=11)

Structured PICO

Does long-term oral amiodarone affect retrograde conduction and refractoriness of the His-Purkinje system in patients with tachycardia?

Population

11 patients with ventricular or supraventricular tachycardia evaluated before and after a mean of 84 days of maintenance oral amiodarone therapy.

Exposure

Oral amiodarone (maintenance dose) for a mean duration of 84 days

Comparator

Baseline (electrophysiological studies before amiodarone treatment)

Outcome

Retrograde conduction (S2H2 interval) and refractoriness of the His-Purkinje system (relative, effective, and functional refractory periods)surrogate

Long-term oral amiodarone significantly prolongs retrograde conduction and increases the refractory periods of the His-Purkinje system, providing mechanistic insight into its antiarrhythmic effects.

Abstract

The effects of long term treatment with oral amiodarone on retrograde conduction ( S2H2 interval) and refractoriness of the His-Purkinje system were studied in 11 patients using His bundle electrograms and the ventricular extrastimulus method. Ten patients had ventricular tachycardia and one supraventricular tachycardia. Electrophysiological studies were carried out before and after the patients had been taking their maintenance dose for a mean duration of 84 days. After amiodarone treatment the HV interval was prolonged in seven patients and unchanged in four. At comparable S1S2 intervals, the S2H2 intervals were longer after treatment with amiodarone in all patients than before. Similarly, the longest S2H2 intervals achieved after amiodarone were longer than the control values. Amiodarone significantly increased the relative, effective, and functional refractory periods of the His-Purkinje system. Thus amiodarone exerts important effects on the His-Purkinje system.

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