Abstract
BACKGROUND: Bioprosthetic mitral valve replacements (MVR) commonly utilize either bovine or porcine valves; however, in terms of structural valve deterioration (SVD), clinical superiority between these valve types remains controversial. The primary objective of this study was to directly compare structural valve deterioration between porcine and bovine bioprosthetic valves used in mitral valve replacement. METHODS: A systematic review was conducted following PRISMA guidelines. Studies directly comparing porcine and bovine bioprosthetic valves in MVR were identified through comprehensive searches of Embase, MEDLINE, and Web of Science databases from inception through March 5, 2025. Eligible studies were cohort studies that directly compared bovine and porcine bioprosthetic valves implanted in the mitral position and reported SVD outcomes. The primary exposure was valve type, and the primary outcomes were reports of SVD. Data extraction included patient demographics, valve characteristics, SVD definitions, and modes of SVD. The Newcastle-Ottawa Scale was used for risk-of-bias assessment. Principal analyses involved narrative synthesis. RESULTS: Nine studies comprising 6,945 patients (range per study: 240-1,695) with follow-up periods ranging from 3.5 to 15 years were included. Three studies favored porcine valves, two favored bovine valves, and four showed no significant difference in terms of SVD. Porcine valves frequently demonstrated leaflet tearing resulting in acute regurgitation, while bovine valves predominantly exhibited calcification leading to stenosis. Younger patients (< 65 years) generally showed better results with porcine valves. Despite variability across studies, cumulative evidence suggested a trend toward superior long-term durability of porcine bioprostheses. CONCLUSIONS: Valve selection should be tailored to patient-specific factors, including age, anticipated longevity, clinical risk profile, and religious preference. Future studies should employ standardized definitions and longitudinal follow-up to clarify these findings.