Survival, Outcomes Similar for Bioprosthetic vs Mechanical MVR in Middle-Aged Patients

Deborah Brauser

April 17, 2015

NEW YORK, NY —The answer to whether bioprosthetic mitral-valve replacement (MVR) is preferable to mechanical for nonelderly patients is "it depends," suggests new research[1].

A retrospective cohort study of patients between the ages of 50 and 69 years who underwent primary, isolated MVR showed no difference 15 years later in survival rates between the two types of valves. Although the patients who received mechanical mitral valves had significantly higher incidents of both stroke and bleeding events, those who received bioprosthetic valves had higher incidents of reoperation.

The choice between these two procedures in patients who are younger than 70 years has been "controversial," note Dr Janna Chikwe (Icahn School of Medicine at Mount Sinai, New York City, NY) and colleagues.

Although bioprosthetic MVR in "the nonelderly" has been increasing steadily, no other large-scale studies have compared it with mechanical MVR in this patient group, write the investigators. And although there were no significant differences found in long-term survival, "there is a trade-off between the incremental risk of reoperation . . . and the greater long-term risk of stroke and major bleeding," they add.

The researchers note that clinicians should go through all benefits/risks of each procedure with patients.

"The lack of survival difference refocuses the emphasis in decision making on the relative risks of major complications and also on quality of life," write Chikwe and colleagues.

The study results were published in the April 14, 2015 issue of the Journal of the American Medical Association.

Patient Preference?

The investigators examined data for 3433 patients (mean age 60 years) who underwent MVR in New York hospitals between 1997 and 2007 and were followed through November 2013. Of these, 76.8% received mechanical prosthetic valves and the remaining 23.2% received bioprosthetic valves. A total of 664 patient pairs were then produced from propensity-score matching, with half undergoing one procedure and half undergoing the other.

In this cohort, the 30-day mortality rate was not significantly different between the bioprosthetic and mechanical MVR groups (5% vs 4%, respectively). There were also no significant between-group differences in long-term all-cause mortality, which was the primary outcome measure (221 vs 209 deaths, respectively), and in actuarial 15-year survival rates (59.9% vs 57.5%, respectively).

When examining secondary end points, the investigators found that incidents of stroke 15 years' postprocedure were significantly higher in the group undergoing mechanical MVR (14%) vs bioprosthetic MVR (6.8%) (HR 1.62, P=0.01), as were cumulative incidents of bleeding events (14.9% vs 9%, respectively) (HR 1.50, P=0.03).

On the other hand, reoperation at 15 years occurred in 11.1% of the bioprosthetic group vs 5.0% of the mechanical group (P=0.03).

"Consensus guidelines have increasingly emphasized patient preference in preoperative decision making, [and] quality-of-life surveys indicate that many patients view the distant possibility of reoperation as a reasonable trade-off for freedom from lifelong anticoagulation."

The investigators add, however, that more research is needed regarding these procedures. Even though the results suggest that bioprosthetic MVR may be a "reasonable alternative" to mechanical MVR in this patient population, "the 15-year follow-up was insufficient to fully assess lifetime risks."

The study was funded in part by a research stipend from the Icahn School of Medicine at Mount Sinai Patient Oriented Research Training and Leadership (PORTAL) Program. Chikwe reports no relevant financial relationships. Disclosures for the coauthors are listed in the article.


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