Midterm survival, clinical, and hemodynamic outcomes of a novel mechanical mitral valve prosthesis

OBJECTIVE: To evaluate the midterm survival, clinical, and hemodynamic outcomes of the On-X mechanical mitral valve, based on the 5-year results of the Prospective Randomized On-X Anticoagulation Clinical Trial (PROACT). METHOD: PROACT Mitral was a multicenter study evaluating 401 patients who underwent mitral valve replacement (MVR) with either Standard or Conform-X On-X mitral valves, comparing low-dose and standard-dose warfarin. Here we report prespecified secondary outcomes of survival, New York Heart Association (NYHA) functional classification, and valve hemodynamics as assessed by core lab-adjudicated echocardiography at 1, 3, and 5 years in the pooled population. RESULTS: Actuarial survival was 99.7% at 1 year, 95.1% at 3 years, and 92.4% at 5 years, with no significant difference between the Standard and Conform-X cuffs. Hemodynamic analysis revealed a mean transvalvular pressure gradient (MG) of 4.6 ± 2.0 mm Hg at 1 year, with no interaction between valve size and patient body surface area. MG values were consistent over time. Quality of life improved with 96.6% of patients in NYHA class I or II at the latest available follow-up of 3 or 5 years. There were no significant differences in survival, clinical, or hemodynamic outcomes between valve sizes. CONCLUSIONS: The On-X mechanical mitral valve demonstrated favorable survival, stable hemodynamics, and enhanced quality of life up to 5 years postimplantation. Derived from high-quality, rigorous randomized trial data, these findings can guide decision making in young patients requiring MVR.