Background:Occasionally atrial fibrillation (AF) is resistant to electrical cardioversion (EC). Ranolazine (RZ) is an antianginal agent, which inhibits abnormal late Na+ channel currents in cardiomyocytes and decreases Na+/Ca++ overload. RZ is a potent inhibitor of after-depolarizations and triggered activity and prolongs atrial refractory periods. We postulated RZ could facilitate EC in patients resistant to EC.
Methods:Over a 3-year period, we identified 25 EC-resistant patients who had been administered oral RZ shortly after failing attempted EC. The anterior-posterior cardioversion approach was used and each patient had failed to be restored to sinus rhythm despite using up to the maximum output of a biphasic cardioversion device. Repeat EC was performed 3.5–4 hours after administration of 2 g of oral RZ using the same device, sedation, and lead placement.
Results: Sinus rhythm was successfully restored in 19 (76%) of 25 EC-resistant patients. Three patients spontaneously converted before the second attempt at EC within 4 hours of the RZ dose. Of the 22 patients undergoing another attempt at EC, 16 were successfully converted to sinus rhythm. Five of the six patients who were refractory to repeat EC despite RZ had AF of unknown duration and each is now in permanent AF. No adverse effects were noted.
Conclusion:RZ shows promise as a safe and convenient agent to facilitate EC in EC-resistant patients. It appears to be most effective in patients whose AF duration is known to be less than 3 months. (PACE 2011;1–6)