Dongyi (Tony) Du, MD, PhD
Division of Epidemiology
Medical Research: What are the main findings of the study?
Dr. Du: The risk for death on the date of surgery was 60% higher for recipients of mechanical aortic valves than recipients of bioprosthetic aortic valves (OR, 1.61 [95%CI, 1.27-2.04; P < .001]; risk ratio [RR], 1.60). The risk difference decreased to 16% during the 30 days after the date of surgery (OR, 1.18 [95%CI, 1.09-1.28; P < .001]; RR, 1.16). The risk for operative mortality was 19% higher for recipients of mechanical compared with bioprosthetic valves (OR, 1.21 [95%CI, 1.13-1.30; P < .001]; RR, 1.19). The number needed to treat with mechanical valves to observe 1 additional death on the surgery date was 290; to observe 1 additional death within 30 days of surgery, 121.
Medical Research: Were any of the findings unexpected?
Dr. Du: It is unexpected that the risk of death during the short period after surgery is higher in mechanical aortic valve recipients than bioprosthetic aortic valves. Mechanical valves are recommended over bioprosthetic valves for patients who are relatively healthier and expected to live longer.
Medical Research: What should clinicians and patients take away from your report?
Dr. Du: This epidemiology study discovered the association or the signal. The causal link cannot be certain until we prove the biological plausibility. However, the clinicians and patients should be aware of this association when they face the decision on which type of prosthetic valves to choose.
Medical Research: What recommendations do you have for future research as a result of this study?
Dr. Du: This association should be confirmed in the Adult Cardiac Surgery Database from the Society of Thoracic Surgeons, where laboratory values are available. If confirmed, pathology study should be performed to identify the root causes.
Du D, McKean S, Kelman JA, et al. Early Mortality After Aortic Valve Replacement With Mechanical Prosthetic vs Bioprosthetic Valves Among Medicare Beneficiaries: A Population-Based Cohort Study. JAMA Intern Med. Published online September 15, 2014. doi:10.1001/jamainternmed.2014.4300.