Expanding indications for transcatheter aortic valve implantation: time for valve-in-valve in mechanical prosthesis? A systematic review and meta-analysis

Aims Following the recent first-in-human experience of Valve in Mechanical Valve (ViMech), interest has emerged in understanding how frequently such an approach might be required in clinical practice. We performed an exploratory meta-analysis to characterize the long-term burden of valve-related complications and reintervention after mechanical aortic valve replacement. Methods Systematic literature search identified studies reporting outcomes of the five most used mechanical aortic valve models (Medtronic/ATS, St. Jude, Carbomedics, Bicarbon, On-X). Descriptive analysis and random-effects meta-analysis assessed late all-cause and valve-related mortality and complications (bleeding, thromboembolism, valve thrombosis, endocarditis, paravalvular leak, reintervention), expressed per 100 patient-years. Results Thirty-two studies encompassing 24,960 patients undergoing mechanical valve replacement were assessed. Isolated mechanical aortic valve replacement was reported in all 32 studies (13,890 patients; 98,987 patient-years; mean follow-up 7.1 years); mean age at implantation was 57.9 years (95% CI 56.3–59.6) and 43% (38–49) were female. Pooled all-cause mortality was 2.39 per 100 patient-years (95% CI 1.92–2.99) and valve-related mortality was 0.55 (0.41–0.73) per 100 patient-years. Bleeding (0.22 [0.16–0.30]) and thromboembolic events (0.18 [0.12–0.25]) were the leading causes of valve-related death. Thromboembolic events (0.94 [0.77–1.14]) and bleeding (0.85 [0.65–1.10]) were the most frequent non-fatal complications, considerably more common than reintervention (0.36 [0.28–0.48] per 100 patient-years). All-cause mortality and complication rates were broadly similar across valve models. Conclusions Mechanical aortic valves show excellent long-term durability with low reintervention rates. Nevertheless, valve-related complications, mainly bleeding and thromboembolism, suggest a small but clinically relevant population in whom redo surgery may carry substantial risk, providing epidemiological context for emerging Valve in Mechanical Valve strategies. Systematic Review Registration https://www.crd.york.ac.uk/PROSPERO/view/CRD420251002419 , identifier CRD420251002419.