Exercise Hemodynamic and Functional Capacity After Mitral Valve Replacement in Patients With Ischemic Mitral Regurgitation: A Comparison of Mechanical Versus Biological Prostheses

Background: In patients with ischemic mitral regurgitation requiring mitral valve replacement (MVR), the choice of the prosthesis type is crucial. The exercise hemodynamic and functional capacity performance in patients with contemporary prostheses have never been investigated. To compare exercise hemodynamic and functional capacity between biological (MVRb) and mechanical (MVRm) prostheses. Methods and Results: We analyzed 86 consecutive patients with ischemic mitral regurgitation who underwent MVRb (n=41) or MVRm (n=45) and coronary artery bypass grafting. All patients underwent preoperative resting echocardiography and 6-minute walking test. At follow-up, exercise stress echocardiography was performed, and the 6-minute walking test was repeated. Resting and exercise indexed effective orifice areas of MVRm were larger when compared with MVRb (resting: 1.30±0.2 versus 1.19±0.3 cm2/m2; P=0.03; exercise: 1.57±0.2 versus 1.18±0.3 cm2/m2; P=0.0001). The MVRm had lower exercise systolic pulmonary arterial pressure at follow-up compared with MVRb (41±5 versus 59±7 mm Hg; P=0.0001). Six-minute walking test distance was improved in the MVRm (pre-operative: 242±43, post-operative: 290±50 m; P=0.001), whereas it remained similar in the MVRb (pre-operative: 250±40, post-operative: 220±44 m; P=0.13). In multivariable analysis, type of prosthesis, exercise indexed effective orifice area, and systolic pulmonary arterial pressure were joint predictors of change in 6-minute walking test (ie, difference between baseline and follow-up). Conclusions: In patients with ischemic mitral regurgitation, bioprostheses are associated with worse hemodynamic performance and reduced functional capacity, when compared with MVRm. Randomized studies with longer follow-up including quality of life and survival data are required to confirm these results.