Effect on circulation of conversion of atrial fibrillation to sinus rhythm.

U NTIL recently enthusiasm for conversion of atrial fibrillation to sinus rhythm in patients with rheumatic heart disease has been dampened by the high rate of reversion to atrial fibrillation soon after conversion. Mitral commissurotomy, if followed by a reduction of left atrial pressure and size, offers the theoretical possibility of a reduction in this reversion rate. Successful commissurotomy of itself, however, does not restore sinus rhythm, and many patients previously in sinus rhythm will fibrillate following surgery. Conversion with quinidine is not a benign procedure and sudden death during conversion attempts has been reported.1Thus the increasing number of patients presenting as candidates for conversion has increased the need for a better understanding of the alterations in cardiac performance that occur as a result of atrial fibrillation and the changes to be expected upon conversion. In 1924, Blumgart2 demonstrated a reduction in heart rate during exercise following conversion to sinus rhythm. Since then, several additional reports have been published comparing various aspects of cardiac performance during exercise before and after conversion from atrial fibrillation to sinus rhythm.3-7 Nevertheless, many aspects of the problem are still in doubt for the following reasons: duplicate control studies in subjects receiving quinidine but not converting have been lacking; it is difficult to determine in most cases how adequately digitalized were