Cardioversion following prosthetic mitral valve replacement.

SUMMARY Direct current conversion of atrial fibrillation has been attempted in 60 consecutive patients following prosthetic mitral valve replacement (Starr-Edwards prosthesis). Sinus rhythm was attained and persisted for at least 24 hours after the procedure in 68% (41 patients) and 40% of the entire group (24 patients) were still in normal sinus rhythm an average of 10 months later. Successful initial conversion and persistence of sinus rhythm occurred most frequently in patients whose duration of atrial fibrillation was less than 5 years and who had a small left atrium. Results differed little whether conversion was attempted 7 to 21 days or 1 to 15 months after open valve replacement. Atrial disease associated with a long period of antecedent atrial fibrillation and marked left atrial enlargement appeared to be the most important factors responsible for persistence of atrial fibrillation or early relapse. Attempts at cardioversion are recommended for all patients with persistent atrial fibrillation following mitral valve replacement in view of the high success rate and the safety of the procedure. THE SAFETY and high initial success of electrical conversion of atrial fibril-lation to sinus rhythm originally demonstrated by Lown and his workers in 19621 have been amply confirmed by many investigators. This study presents the results of electrical conversion of atrial fibrillation in a consecutive group of patients who have had prosthetic mitral valve replacement. Following effective mitral valve replacement , resting left atrial pressure is frequently normal and lower than that following closed nonreplacement techniques.2 6 For this reason it might be expected that conversion of atrial fibrillation following valve-replacement surgery would be easier to achieve and maintain than it is following nonreplacement surgery. In addition, investigation of this problem would provide information regarding factors tending to perpetuate atrial fibrillation in patients with normal resting left atrial pressure. Methods Postoperative cardioversion using a standard DC discharge was attempted in patients who had atrial fibrillation preceding insertion of a Starr-Edwards caged-ball mitral prosthesis. Consecutive patients were chosen for this study without consideration being given to age or duration of fibrillation. Left atrial enlargement was graded slight, moderate, or marked by examination of standard four view cardiac roentgenograms with barium in the esophagus. Additional information regarding left atrial size was obtained by inspection at the time of surgery. Pertinent clinical data are summarized in table 1. The Lown DC cardioverter* was used according to the technique previously described.7 When possible, anteroposterior …