Limited internal shocks for atrial fibrillation refractory to external cardioversion

We investigated the feasibility and long-term results of low-energy internal defibrillation using a limited number of shocks in patients with persistent atrial fibrillation resistant to external cardioversion. A relatively high number of shocks of lower energy are usually required in those cases and can be poorly tolerated.

Twenty-five patients with persistent atrial fibrillation underwent internal defibrillation, using biphasic R wave synchronous shocks between two catheters in the high right atrium and the coronary sinus. Conversion to sinus rhythm was obtained in all patients, with a median of two shocks. Early recurrence of atrial fibrillation (AF) occurred in eight cases (32%). Seven patients (41%) out of 17 discharged in sinus rhythm remained free of AF after a median follow-up of 8.9 months. Severe mitral insufficiency (P=0.05) and low left ventricle ejection fraction (P=0.002) were correlated with earlier recurrence. Amiodarone significantly favored (P=0.019) maintenance of sinus rhythm.

Internal defibrillation using a limited number of shocks equal to or less than 30 Joules is effective in terminating refractory atrial fibrillation and could be more acceptable for patients. However, the recurrence rate remains high, particularly in patients with severe mitral insufficiency or poor ventricular function. Amiodarone delays recurrences of atrial fibrillation.