Key result
Long-term amiodarone treatment significantly increased the effective refractory period of all stimulated pulmonary veins compared to no antiarrhythmic therapy (210 vs 174 msec; P=0.0001).
Why the study?
Does continuous long-term treatment with amiodarone alter the effective refractory period of pulmonary veins in patients with symptomatic and drug-resistant paroxysmal atrial fibrillation?
Observational (n=55)
Does continuous long-term treatment with amiodarone alter the effective refractory period of pulmonary veins in patients with symptomatic and drug-resistant paroxysmal atrial fibrillation?
Absolute Event Rate: 210% vs 174%
p-value: p=0.0001
Long-term amiodarone therapy heterogeneously increases the effective refractory period of pulmonary veins, which may explain its antiarrhythmic efficacy in paroxysmal atrial fibrillation.
May support mechanistic basis for amiodarone efficacy in paroxysmal AF; cross-sectional data leave open need for prospective confirmation.
INTRODUCTION: Pulmonary veins (PVs) are the predominant location of triggers for atrial fibrillation (AF), but little is known about the electrophysiologic properties of PVs. In addition, the influence of amiodarone on the electrophysiologic properties of PVs has not been elucidated. METHODS AND RESULTS: Fifty-five patients with symptomatic and drug-resistant AF were divided into two groups: group 1 patients (n=29) without antiarrhythmic drug therapy at the time of electrophysiologic study (EPS), and group 2 patients (n=26) undergoing continuous long-term treatment with amiodarone. EPS including programmed stimulation of both atria and within the PVs was performed in both groups. In group 1, the effective refractory period (ERP) of all PVs (174 +/- 62 msec) was significantly shorter than the ERP of the left atrium ([LA] 254 +/- 30 msec, P=0.0001) and right atrium ([RA] 221 +/- 29 msec, P=0.0001). The same pattern was observed in group 2 (PV: 210 +/- 58 msec; LA: 259 +/- 35 msec, P=0.0001; RA: 246 +/- 37 msec, P=0.0255). The ERP of all stimulated PVs was significantly lower in group 1 (174 +/- 62 msec) than in group 2 (210 +/- 58 msec; P=0.0001). The ERP of the left superior and right superior PVs and RA but not the left inferior PV and LA were significantly increased in patients treated with amiodarone. Decremental conduction properties were observed in all stimulated PVs, and there were no significantly differences between the maximal decrement of both groups. CONCLUSION: The distinctive electrophysiologic properties of PVs are emphasized by amiodarone therapy. Long-term amiodarone treatment is responsible for heterogeneous alteration of the PV electrophysiology, which may account for the individual antiarrhythmic responses in a subset of patients with paroxysmal AF.
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Rostock et al. (2005) conducted an observational in Paroxysmal atrial fibrillation (n=55). Amiodarone vs. No antiarrhythmic drug therapy was evaluated on Effective refractory period of all stimulated pulmonary veins (p=0.0001). Long-term amiodarone treatment significantly increased the effective refractory period of all stimulated pulmonary veins compared to no antiarrhythmic therapy (210 vs 174 msec; P=0.0001).
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