Mitral regurgitation is the most common cardiac valve pathology. The prevalence of moderate to severe mitral regurgitation in a general population aged 75 years and older is approximately 10% and its presence generally contributes to an impaired prognosis for the patients. Surgical mitral valve repair (particularly in degenerative mitral regurgitation) is widely established based on excellent long-term outcomes and effective reduction of mitral regurgitation. In functional mitral regurgitation, isolated mitral valve surgery is less well established owing to poorer surgical results and the lack of evidence for a benefit of surgery over medical therapy. This is related to the fact that in functional mitral regurgitation, the valvular incompetence may appear secondary to changes in left ventricular size and geometry, and thereby contribute to a variable extent to the underlying pathophysiology of congestive heart failure. Moreover, many patients with severe mitral regurgitation are denied surgery as a result of their high surgical risk because of age, poor left ventricular function, or other comorbidities.
Treatment strategies for patients with mitral regurgitation (MR) are changing. Current guidelines suggest that patients with symptoms, atrial arrhythmias (especially atrial fibrillation), pulmonary hypertension, or left ventricular (LV) decompensation heralded by changes in LV ejection fraction should undergo mitral valve surgery. In addition, for patients in whom valvular repair is likely, the guidelines also suggest that an asymptomatic patient with severe MR and normal LV function might undergo mitral valve repair to prevent the sequelae of chronic MR. Earlier and earlier treatment and mitral valve repair are now the surgical norm. In one sense, the guard is already changing.
Repair of the mitral valve is associated with an at least equivalent late survival rate compared with replacement, and perhaps lower operative risk. A reduced risk of endocarditis, fewer thromboembolic complications, and better preservation of LV function make repair an attractive strategy; however, successful mitral valve surgery is dependent on individual valve pathology. In rheumatic mitral regurgitation, the distorted leaflet anatomy, associated subvalvular fibrosis, and calcification rarely allow valve repair. Patients with ischemic or congestive heart disease, LV remodeling, annular dilation, alteration of the subvalvular apparatus, and distorted leaflet coaptation present special challenges. Most surgeons attempt a complete repair, combining direct valvular restoration with an annuloplasty device. If the guard is to change successfully as we move toward percutaneous transcatheter repair, then valuable lessons learned during many years of surgical experience must not be forgotten. The challenges are magnified several fold in percutaneous approaches.