Bioprosthetic vs. Mechanical Mitral Valve Replacement in Patients Aged 50-69 Years | Journal Scan

Study Questions:

Among patients 50-69 years of age undergoing mitral valve replacement, is there a survival advantage associated with a mechanical versus a bioprosthetic valve?

Methods:

In a retrospective cohort analysis, outcomes of 3,433 patients aged 50-69 years who underwent primary isolated mitral valve replacement in New York State hospitals from 1997-2007 were analyzed. Median follow-up duration was 8.2 years (range 0-16.8 years). Propensity score matching for 19 baseline characteristics yielded 664 patient pairs. The main outcome measures were all-cause mortality, stroke, reoperation, and major bleeding events.

Results:

No survival difference was observed between use of mechanical and bioprosthetic mitral valves in patients aged 50-69 years matched by propensity score (actuarial 15-year survival 57.5% [95% confidence interval (CI) 50.5-64.4%] vs. 59.9% [95% CI 54.8-65.0%], hazard ratio [HR] 0.95 [95% CI 0.79-1.15]), or in a subgroup analysis of age by decade. Among patients matched by propensity score, mechanical versus bioprosthetic mitral valve replacement was associated with higher 15-year incidence of stroke (14.0% [95% CI 9.5-18.6%] vs. 6.8% [95% CI 4.5-8.8%], HR 1.62 [95% CI 1.10-2.39]) and bleeding events (14.9% [95% CI 11.0-18.8%] vs. 9.0% [95% CI 6.4-11.5%], HR 1.50 [95% CI 1.05-2.16]), but a lower incidence of reoperation (5.0% [95% CI 3.1-6.9%] vs. 11.1% [95% CI 7.6-14.6%], HR 0.59 [95% CI 0.37-0.94]).

Conclusions:

Among patients aged 50-69 years undergoing mitral valve replacement in New York State, there was no significant survival difference at 15 years in patients matched by propensity score who underwent mechanical prosthetic versus bioprosthetic mitral valve replacement. Mechanical prosthetic valves were associated with lower risk of reoperation, but greater risk of bleeding and stroke. The authors note that, even though these findings suggest that bioprosthetic mitral valve replacement may be a reasonable alternative to mechanical prosthetic valve replacement in patients aged 50-69 years, the 15-year follow-up was insufficient to fully assess lifetime risks, particularly of reoperation.

Perspective:

Data from old prospective randomized trials performed in the late 1970s to early 1980s suggested a mortality advantage in younger patients after mechanical compared to bioprosthetic mitral valve replacement. Since then, this study and other studies of contemporary surgery and contemporary prostheses suggest no mortality difference, likely related to better prostheses and lower re-operative risks compared to the historical trials. Prosthetic valve choice among patients <60-65 years of age remains ideally based on the preference of a well-informed patient. Data from this study should help reinforce that there is a trade-off in terms of likelihood of reoperation versus likelihood of bleeding (and perhaps stroke). The advent of valve-in-valve transcatheter therapies following bioprosthetic mitral valve replacement also might decrease the invasiveness of re-do procedures in a younger population.

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention

Keywords: Bioprosthesis, Heart Valve Prosthesis, Incidence, Mitral Valve, Mortality, Outcome Assessment (Health Care), Reoperation, Risk, Stroke, Survival, Cohort Studies, Retrospective Studies, Follow-Up Studies, Cardiac Surgical Procedures


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