Implications of Prolonged Pause in Patients with Chronic Atrial Fibrillation with Mitral Valve Disease Undergoing Atrial Compartment Operation

Abstract

Background and Purpose: Prolonged pause is commonly seen in patients with atrial, fibrillation (AF), but the electrophysiologic mechanism and clinical importance of this phenomenon are not clear. This study examined the incidence and clinical importance of prolonged pause in patients with chronic AF and mitral valve disease before and after AF surgery. Methods: Holter recordings were made in 53 mitral valve patients undergoing concomitant valve surgery and atrial compartment operation for chronic AF. There were 38 patients (72%) with successful AF conversion and 15 patients (28%) with failed AF conversion. Cardiac rhythms before and after operation were compared. An R-R interval greater than or equal to 2.0 sec was defined as prolonged pause. Serum digoxin and potassium concentration were determined within 24 hours of Holter monitoring. Results: Before operation, prolonged ventricular pause was common during AF in both groups (76% for the successful AF conversion group and 73% for the failed AF conversion group, p > 0.05). There were 62 77 episodes of prolonged pause in the successful AF conversion group and 59 44 in the failed group (p > 0 .05). The longest pause lasted 2.47 +/- 0.26 sec in the successful AF conversion group and 2.43 +/- 0.41 sec in the failed AF conversion group ( p > 0.05), with most prolonged pauses occurring at night (72% in the successful and 73% in the failed AF conversion group, p > 0.05). After conversion to sinus rhythm, only 1 patient (3%) showed an episode of prolonged pause (p < 0.001). No patient exhibited atrioventricular (AV) block. In patients with successful AF conversion, the maximal heart rate decreased from 150 +/- 28 to 126 +/- 17 beats/min (p < 0.001), the minimal heart rate increased from 43 +/- 6 to 56 5 beats/min (p < 0.001), and ventricular premature beats (VPB) counts decreased from 599+ /- 935 to 223 +/- 453/24 hours (p < 0.05). In contrast, patients with failed AF conversion showed no significant changes in the incidence of prolonged pause, maximal and minimal heart rates, and VPB counts after operation. None of the patients received pacemaker implantation during a mean follow- up period of 42 +/- 11 months in the successful group and 45 +/- 13 months in the failed AF conversion group. Conclusion: We conclude that prolonged pause is common in AF with mitral valve disease and does not indicate the presence of sinus or AV nodal dysfunction requiring artificial pacing.