Changes in atrial electrical properties following cardioversion of chronicatrial fibrillation: relation with recurrence

Objective: To study the reversibility of atrial electrical remodeling and i ts relation with recurrence in post-conversion chronic atrial fibrillation (CAF) patients. Methods: In 28 drug-free CAF patients (mean AF duration 41/-39 months) electrically converted to sinus rhythm effective refractory pe riod (ERP) at 500 ms, monophasic action potential at 90% of repolarization (MAPd90) at five cycle lengths (CL, 350, 400, 450, 500, 600 ms), and P wave duration were measured three times: within the interval 5-20 min post-conv ersion, 24 h and 1 month later. Fifteen subjects with no history of AF and normal atrial structure served as a control group. Patients were followed u p for recurrence for 1 month; 12 relapsed. Results: ERP changed from 205+/- 20 to 243+/-31 to 241+/-24 ms (P<0.001), attaining a level comparable to th at of the controls (238+/-21 ms) within 24 h. MAPd90 significantly (P<0.001 ) increased (from 175+/-11 to 190+/-19 to 191+/-10 ms at CL 350 ms and 201/-12 to 234+/-20 and 233+/-23 ms at CL 600 ms) also reaching control levels within 24 h. MAPd90 exhibited an abnormal adaptation to rate only in the f irst evaluation. P wave duration was prolonged (137+/-33 ms) and exhibited a slower course of shortening (130+/-32 to 123+/-27 ms, P<0.001), reaching control levels within 1 month. Patients with higher values of MAPd90 at CL 350 in the immediate post-conversion period were more likely to relapse (P< 0.005). Conclusions: ERP and repolarization shortening as a result of CAF a re reversed within 24 h after conversion, while P wave duration reduces mor e slowly. Post-conversion MAPd90 values contain prognostic information for recurrence. (C) 2000 Elsevier Science B.V. All rights reserved.