Patient risk factors for bioprosthetic aortic valve degeneration: a systematic review and meta-analysis

The choice of valve type for aortic valve replacement surgery is sometimes challenging. The main risk for bioprostheses is structural valve degeneration (SVD); however, little is known about what the most important risk factors are. We conducted a systematic review and meta-analysis to identify the risk factors and estimate their pooled effect sizes to aid the prosthesis choice for replacement. We followed PRISMA guidelines and systematically searched three electronic databases (PubMed, Scopus, and Web of Science) using appropriate key terms: 'aortic valve', 'bioprosthesis', 'degeneration', 'durability', 'prosthesis failure', etc. Hazard ratio (HR) and odds ratio (OR) and associated 95% confidence intervals (CI) were extracted. Pooled risk estimates were calculated using a random-effects model. Twenty-nine (29) observational studies were included with a total of 25,490 patients, 981 of whom developed SVD over a mean follow-up time of 18.5 years. Four (4) factors influencing bioprosthetic SVD were identified: increasing age was a protective factor (per 1-yr increase, HR: 0.91 [95% CI 0.89, 0.94], p<0.0001), whereas increased body surface area (HR 1.77 [1.04, 3.01], p=0.034), patient-prosthesis mismatch (HR 1.95 [1.56, 2.43], p<0.001), and smoking (HR 2.28 [1.37, 3.79], p=0.0015) were risk factors for SVD. We found younger age, patient-prosthesis mismatch, body surface area, and smoking, as risk factors for aortic SVD, which should be considered for valve selection. This study generates a further hypothesis that accelerated flow across the valve is a shared key component in the pathophysiology of SVD, thus future research should consider other high cardiac output states.