Rationale of the Cox maze procedure for atrial fibrillation during redo mitral valve operations.

OBJECTIVE

The frequency of reoperation for mitral valve diseases with chronic atrial fibrillation has increased steadily. This study examined the rationale for using the Cox maze operation for atrial fibrillation during redo mitral valve operations.

METHODS

Between June 1992 and July 1995, we performed the maze procedure in 42 patients as a concomitant operation with redo mitral valve surgery (maze group). Associated procedures were tricuspid valve surgery in 27 patients and aortic valve surgery in 15 patients. The mean age at operation was 57.3 +/- 9.7 years, and the mean interval from the previous operation was 14.3 +/- 10.5 years. The mean follow-up period after the maze procedure was 25.5 +/- 10.8 months. Atrial fibrillation was present at the time of the previous operation in 29 patients (69%).

RESULTS

Neither hospital death nor late death occurred. Sinus rhythm was regained in 28 patients (67%), and an atrial A-wave was detected in 21 patients (50%) by pulsed Doppler study. Patients in whom sinus rhythm was restored had a shorter history of atrial fibrillation (9.0 +/- 6.0 years vs 15.9 +/- 4.6 years, p = 0.0009), a larger f-wave on lead V1 of the electrocardiogram (0.18 +/- 0.10 mV vs 0.10 +/- 0.08 mV, p = 0.017), and a smaller cardiothoracic ratio (63% +/- 8% vs 67% +/- 5%, p = 0.049) than patients with persistent atrial fibrillation. During the same period, 54 patients underwent mitral valve reoperation without the maze procedure (control group). The aortic crossclamp and cardiopulmonary bypass times were slightly longer (p = 0.048 and p = 0.012) in the maze group (133 +/- 28 minutes and 221 +/- 43 minutes) than in the control group (126 +/- 65 minutes and 197 +/- 78 minutes). There was no significant difference in the amount of chest tube drainage or transfusion between the two groups (890 +/- 510 ml and 2120 +/- 1600 ml, respectively, in the maze group and 840 +/- 480 ml and 2140 +/- 1760 ml, respectively, in the control group). It was not necessary to reopen the chest for bleeding significantly more often in one group than in the other (14% in the maze group and 7% in the control group), and it was possible to operate without transfusion with the same frequency in the two groups (17% in the maze group and 20% in the control group).

CONCLUSION

These results suggest that the maze procedure should be considered in selected patients who have a high possibility of regaining sinus rhythm during redo mitral valve operations.