Among younger patients who underwent mitral valve replacement, 15-year survival was not significantly different between those who received bioprosthetic valves and those who received mechanical devices, based on data from a retrospective study published online April 14 in JAMA.
However, “there is a tradeoff between the incremental risk of reoperation associated with bioprosthetic valves and the greater long-term risk of stroke and major bleeding with mechanical prosthetic valves,” said Dr. Joanna Chikwe of Mount Sinai Hospital, New York, and her associates.
“Even though [our] findings suggest bioprosthetic 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,” the researchers noted (JAMA 2015;313:1435-42 [doi:10.1001/jama.2015.3164]).
The choice between bioprosthetic and mechanical mitral valves is controversial in patients younger than 70 years. Bioprosthetics are much more likely to degenerate over time and require reoperation, but mechanical valves put recipients at increased risk of thromboembolism and hemorrhage and require lifelong anticoagulation. In this age group, the use of bioprosthetic devices has steadily and markedly increased in the past decade, from a small fraction of patients to the majority of patients. Yet until now, no large-scale studies have compared long-term survival and other outcomes between the two valves in this patient population.
Dr. Chikwe and her associates reviewed data from a New York state database of all inpatient hospitalizations. They included 3,433 patients aged 50-69 years at baseline who underwent mitral valve replacement with bioprosthetic (23.2%) or mechanical (76.8%) devices from 1997 through 2007. They also assessed a subset of 664 patient pairs who were propensity matched.
After a median follow-up of 8.2 years (maximum, 16.8 years), there was no significant difference in long-term survival between the two groups. Actuarial 15-year survival was 59.9% with bioprosthetic valves and 57.5% with mechanical devices, the investigators said.
This lack of survival difference “refocuses the emphasis” onto major complications and quality of life, the researchers noted. Regarding these secondary outcomes, the incidence of stroke was significantly higher with mechanical mitral valves (14.0% vs 6.8%) and carried a high mortality (8.5%). The incidence of serious bleeding events also was significantly higher with mechanical valves (14.9% vs 9.0%), and also carried a high (7.4%) mortality. Such risks should “be a major consideration in any discussion of prosthesis choice,” Dr. Chikwe and her associates noted.
Conversely, the incidence of mitral valve reoperation was significantly lower with mechanical devices (5.0% vs 11.1%), and related mortality was 5.3%.
These findings differ from those of recent single-center retrospective series, which reported a long-term survival benefit with mechanical valves in younger patients. Those studies, however, were much smaller and had methodological flaws such as failure to control for competing causes of death, the investigators noted.
This study was supported in part by the Mount Sinai School of Medicine, New York, which receives royalties from Edwards Lifesciences and Medtronic for heart valve devices. Dr. Chikwe reported having no relevant financial disclosures; one of her associates reported ties to Medtronic.
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