Background There have been no single-center studies that have systematically addressed the acute outcome of Inoue balloon mitral commissurotomy (BMC) performed in a large series of patients. Accordingly, this study sought to examine the impact of operator experience and continuing technical modifications on the success and complication rates of BMC. Methods BMC was performed in 799 patients: 469 patients with pliable mitral valves (group 1) and 330 patients with calcified valves and/or severe subvalvular disease (group 2). Acute complications were examined and compared between groups before and after modifications in BMC techniques. Major modifications included the use of a height-derived balloon sizing method for the selection of an appropriate balloon catheter, a cautionary stepwise dilation technique, and avoidance of traction on the interatrial septum during balloon inflations. Results Technical failures were encountered in 4 (0.5%) patients in our early experience. One patient sustained cardiac perforation and tamponade and was the only case requiring emergency surgery, There were no deaths. Systemic embolic events were observed in 1 1 (1.4%), all among the first 353 patients before the routine use of pre-BMC transesophageal echocardiography. Severe postprocedure angiographic (greater than or equal to 3+) mitral regurgitation occurred in 4% of patients, 2% in group 1 versus 9% in group 2 (P = .0001). With increased operator experience and technical modifications, this complication was significantly reduced from 5% (7 of 150 patients) to 0% in the last 316 patients in group 1 (P = .0001) and from 1 1% (26 of 228 patients) to 3% (3 of 101 patients) in group 2 (P = .031). The incidence of significant interatrial shunting (pulmonary-to-systemic flow ratio greater than or equal to 1.3) was also significantly reduced from 12% to 6% (P = .0034). Conclusion Incremental operator experience and ongoing technical refinements in BMC techniques have resulted in a 100% technical success rate and a significant diminution in complications in patients with a wide spectrum of stenotic mitral valve morphologic features.
