Aim: Changes in ventricular refractoriness and repolarization after successful electrical cardioversion to sinus rhythm in persistent atrial fibrillation (AF) patients were studied.
Methods and results: In 33 AF patients with controlled ventricular response, right ventricular ERP (VERP) at three basic cycle lengths (600, 500, 400 ms), as well as monophasic action potential duration (MAPd(90)) at a drive cycle length of 500 ms, were measured just before, 20 min and 24 h after cardioversion. VERP at 600 ms changed from 241+/-19 ms to 249+/-21 ms to 253+/-24 ms (P<0.001), VERP at 500 ms changed from 234+/-19 ms to 242+/-22 ms to 246+/-23 ms (P<0.001) and VERP at 400 ms changed from 224+/-20 ms to 232+/-23 ms to 236+/-24 ms (P<0.001). MAPd(90) changed from 247+/-16 ms preconversion to 252+/-17 ms 20 min postconversion to 253+/-19 ms after 24 h (P<0.05). Change in refractoriness at 500 ms was well correlated with change of mean RR interval before and 20 min after conversion (R=0.616, P<0.001). There was no correlation between RR variability and VERP before cardioversion.
Conclusion: Restoration of sinus rhythm in persistent AF patients is followed by significant effects on ventricular refractoriness and repolarization related to cycle length change. No AF related ventricular electrophysiological alterations were found.