ELECTROCARDIOGRAPHIC NATURE OF RESTORED SINUS RHYTHM AFTER COX MAZE PROCEDURE IN PATIENTS WITH CHRONIC ATRIAL-FIBRILLATION WHO ALSO HAD OTHER CARDIAC-SURGERY

Objective-To characterise heart rate variability and high frequency co mponents of restored sinus rhythm after the maze procedure. The maze p rocedure for chronic atrial fibrillation wagr prevent thrombotic event s and improve the quality of life. However, the electrocardiographic n ature of restored sinus rhythm after the maze procedure has not been f ully elucidated. Patients and methods-Between March 1993 and August 19 95, 104 consecutive patients undergoing the maze procedure in combinat ion with other cardiac surgery were studied. There were 100 long-term survivors (78 with mitral valve disease, 9 with aortic valve disease, 8 with congenital heart disease, and 5 others). Twenty age-matched pat ients with mitral valve disease who were in normal sinus rhythm preope ratively were enrolled as a control group. 30 days after surgery, the presence of arrhythmias and the circadian changes of heart rate variab ility were estimated by ambulatory electrocardiographic monitoring and the filtered P duration was evaluated by signal-averaged electrocardi ogram. Results-Restoration of sinus rhythm was observed in 73 of 100 c ases. Subjects were classified into three groups according to their po stoperative ambulatory electrocardiographic monitoring findings: patie nts in group 1 (n = 73) (1a: 58 regular sinus rhythm; 1b: 15 sinus rhy thm with frequent premature atrial contractions (> 1000/day)); patient s in group 2 (n = 21) still had persistent atrial fibrillation; and pa tients in group 3 (n = 6) required permanent pacemaker implantation be cause of sick sinus syndrome. The success rate of restoration of sinus rhythm was 88.3% if left atrial diameter was small (< 65 nmn). Circad ian changes in the low frequency to high frequency power ratio in grou p la were significantly diminished compared with control group (P < 0. 01). Furthermore, the filtered P durations in group 1a (150 (20) ms) a nd group 1b (158 (23) ms) were longer than in the control group (122 ( 11) ms) (P < 0.01). Conclusions-The maze procedure may result in a dec reased sinus response and non-uniform transmission of impulses in the atrium.