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Mechanical surgical valves superior to bioprosthetic valves in mortality
Patients who received a mechanical prosthesis for surgical mitral valve or aortic valve replacement had a long-term mortality benefit compared with those who received a biologic prosthesis, according to a study published in The New England Journal of Medicine.
The mortality benefit for patients who received a mechanical prosthesis vs. those who received a biologic prosthesis continued until age 55 years for aortic valve replacement and until age 70 years for mitral valve replacement, the researchers wrote.
“This has potential to significantly impact the current national practice guidelines,” Y. Joseph Woo, MD, professor and chair of cardiothoracic surgery at Stanford University and a Cardiology Today Editorial Board Member, said in a press release. “While our preference is always to repair heart valves whenever possible, there are certain disease processes which necessitate valve replacement. For these patients, given the study’s new and unexpected findings, I am already pondering, ‘How am I going to counsel my patients today?’ The advice may not be the same as the current national guideline recommendations.”
Valve replacements
Andrew B. Goldstone, MD, a postdoctoral research fellow at Stanford University School of Medicine at the time of the study and now a cardiothoracic surgery resident at Hospital of the University of Pennsylvania, and colleagues analyzed data from 9,942 patients who underwent aortic valve replacement and 15,503 patients who underwent mitral valve replacement at hospitals in California from 1996 to 2013. Patients who underwent either procedure had a biologic or mechanical prosthesis implanted. Those with multiple valve replacements, previous cardiac surgery, mitral or aortic valve repair and thoracic aortic surgery were excluded.
In the aortic valve cohort, age stratification was 45 to 54 years and 55 to 64 years; in the mitral valve cohort, it was 40 to 49 years, 50 to 69 years and 70 to 79 years.
Mortality was the primary endpoint. Secondary endpoints were defined as mortality up to 30 days after surgery and a cumulative incidence of bleeding, stroke or reoperation.
Median follow-up was 5 years for biologic prosthesis in aortic valve replacement, 8.2 years for mechanical prosthesis in aortic valve replacement, 4.6 years for biologic prosthesis in mitral valve replacement and 7.6 years for mechanical prosthesis in mitral valve replacement.
The rate of use of biologic prostheses in aortic valve replacement increased from 11.5% in 1996 to 51.6% in 2013 (P < .001). There was also an increase in biologic prostheses in mitral valve replacement from 1996 (16.8%) to 2013 (53.7%; P < .001).
Varied benefits
In the aortic valve cohort, patients aged 45 to 54 years who received a biologic prosthesis had a higher rate of mortality at 15 years (30.6%) vs. those in the same age group who received a mechanical prosthesis (26.4%; HR = 1.23; 95% CI, 1.02-1.48). This difference was not seen in patients aged 55 to 64 years. Incorporating the hospital as a random effect or multivariable adjustment did not affect the results.
At 15 years, in the group aged 40 to 49 years, those who received a biologic mitral valve prothesis had a higher rate of mortality (44.1%) vs. patients who received a mechanical mitral valve (27.1%; HR = 1.88; 95% CI, 1.35-2.63). This difference was also seen in the 50 to 69 years age group (50% vs. 45.3%; HR = 1.16; 95% CI, 1.04-1.3), but not in those aged 70 to 79 years.
Patients aged 45 to 54 years who received a biologic prosthesis for aortic valve replacement and patients aged 50 to 69 years who received a biologic prosthesis for mitral valve replacement had a lower incidence of stroke compared with those who received a mechanical prosthesis.
The incidence of bleeding was lower in both age groups for patients who underwent a biologic aortic valve replacement and those aged 50 to 69 years and 70 years to 79 years in the biologic mitral valve replacement group compared with those who received a mechanical prosthesis.
The odds of reoperation were higher in patients who received a biologic prosthesis for both mitral valve and aortic valve replacement vs. those who received a mechanical prosthesis.
“Reoperation rates diverged as early as 6 to 8 years after the index valve replacement and coincided with the emergence of between-group differences in mortality in both the aortic valve replacement cohort and the mitral valve replacement cohort,” Goldstone and colleagues wrote. “Therefore, structural valve deterioration — which is underestimated by the cumulative incidence of reoperation — and subsequent reoperation may partially explain the difference in mortality. As transcatheter technologies develop, the risk associated with reoperative surgery will change.” – by Darlene Dobkowski
Disclosure: Goldstone and Woo report no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.