Why do mitral valve repairs fail?

In this issue of JASE, Magne et al continue their previous work using echocardiography to analyze outcomes of mitral valve repair for ischemic mitral regurgitation, demonstrating that continued adverse left ventricular (LV) remodeling may not be a prerequisite for recurrent mitral valve regurgitation in patients who had undergone initially successful repairs. They observed a group of 26 patients selected from a larger group who had undergone surgical repair for ischemic mitral regurgitation and noted that 10 patients developed recurrent mitral regurgitation within a mean of 18 months after surgery. In those 10 patients, recurrent regurgitation was ascribed to continued adverse LVremodeling in 5 patients, while the other 5 did not have detectable changes in ventricular volumes. The authors did note increased tethering of the anterior leaflet in the latter group of patients and suggested that recurrent regurgitation was due to localized LV remodeling in the vicinity of the papillary muscle. Does this finding represent an advance in our understanding of ischemic mitral valve repair? Have alternate explanations for recurrent regurgitation been excluded? To help put these findings in perspective, it is necessary to review the pathophysiology of ischemic mitral valve regurgitation and to separate the issue of residual or recurrent mitral regurgitation that results from surgical technical failure, as opposed to that due to the progression of the underlying disease process.