[Follow-up study of atrial fibrillation associated with mitral stenosis after D-C cardioversion following open mitral commissurotomy].

We studied cardiac rhythm in 167 patients with mitral stenosis following open mitral commissurotomy in the last 7 years. After surgery 76 patients (72%) out of 106 patients who presented atrial fibrillation before surgery were reverted back to sinus rhythm by D-C cardioversion. Forty-three patients (41%) maintained sinus rhythm at the time of discharge from hospital, and 30 patients (28%) maintained it for 2.5 years (average) after surgery. The actuarial maintenance rate of sinus rhythm was 50 + 11% 7 years after surgery in these 43 patients. Ninety-three% of the 30 patients who reverted to and maintained sinus rhythm improved to class I (New York Heart Association criteria), whereas 47% of the 78 patients who retained atrial fibrillation remained in class II or III after surgery. In 30 patients who reverted back to sinus rhythm and maintained it late postoperatively, the preoperative duration of atrial fibrillation was up to 5 years, and 35% of the patients had had atrial fibrillation for more than 1 year. Also, in 40% of these 30 patients, the preoperative cardiothoracic ratio was more than 60%. Therefore, in the patients who reverted to atrial fibrillation immediately after surgery, secondary D-C cardioversion should be performed under stable hemodynamic conditions 10 to 14 days after surgery, even if their preoperative duration of atrial fibrillation was more than 1 year or their preoperative cardiothoracic ratio was more than 60%.