THE PROGNOSIS OF ATRIAL FIBRILLATION FOLLOWING MITRAL VALVOTOMY

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Abstract
Of 331 patients who under -went valvotomy, 151 (45%) were in sinus rhythm. Atrial fibrillation developed in 46 (30%) of the 151 patients in sinus rhythm during or shortly after valvotomy. Twelve (44%) of 27 such patients reverted to sinus rhythm spontaneously, but 4 of the 12 relapsed into atrial fibrillation after an average period of follow-up of two and a half years. Of 6 patients who have been followed for 4 years, 2 are still in sinus rhythm. The most important factor in determining whether spontaneous reversion would take place was the time of onset of the atrial fibrillation. Where the onset was in the 1st postoperative week there was a 60% chance of spontaneous reversion. Where the onset was later, spontaneous reversion did not take place. Quinidine restored sinus rhythm in 13(68%) of 19 cases of postoperative atrial fibrillation who had not reverted spontaneously after 2 weeks. The average dose required was 1.4 g. Eleven (85%) of the 13 cases relapsed into atrial fibrillation after an average follow-up for 2 years. Of 8 patients who have been followed for 4 years, 2(25%) are still in sinus rhythm. Quinidine had a slight advantage over the results of spontaneous reversion in those developing atrial fibrillation post-operatively, but this difference was not statistically significant (p=0.2-0.1). The relapse rate was greater in the group treated with quinidine so that 4 years after operation this advantage was lost. Of 179 patients who underwent mitral valvotomy in atrial fibrillation, only 1 reverted to sinus rhythm spontaneously. Quinidine restored sinus rhythm in 6 (22%) of 27 cases of preoperative atrial fibrillation: the average dose required was 2.8 g; 5 (80%) of the 6 had relapsed into atrial fibrillation 6 months later. There were 2 unexpected deaths in the 46 patients during treatment with quinidine.