Mechanical aortic valve replacement in non-elderly adults: meta-analysis and microsimulation.

__Aims__ To support decision-making regarding prosthetic valve selection in non-elderly adults, we aim to provide a detailed overview of outcome after contemporary mechanical aortic valve replacement (AVR). __Methods and results__ A systematic review was conducted for papers reporting clinical outcome after AVR with bileaflet mechanical valves with a mean patient age ≥18 and ≤55 years, published between 1 January 1995 and 31 December 2015. Through meta-analysis outcomes were pooled and entered into a microsimulation model to calculate (event-free) life expectancy and lifetime event risk. Twenty-nine publications, encompassing a total of 5728 patients with 32 515 patient-years of follow-up (pooled mean follow-up: 5.7 years), were included. Pooled mean age at surgery was 48.0 years. Pooled early mortality risk was 3.15% (95% confidence interval (CI):2.37-4.23), late mortality rate was 1.55%/year (95%CI:1.25-1.92); 38.7% of late deaths were valve-related. Pooled thromboembolism rate was 0.90%/year (95%CI:0.68-1.21), major bleeding 0.85%/year (95%CI:0.65-1.12), nonstructural valve dysfunction 0.39%/year (95%CI:0.21-0.76), endocarditis 0.41%/year (95%CI:0.29-0.57), valve thrombosis 0.14%/year (95%CI:0.08-0.25), structural valve deterioration 0.00%/year (zero events observed), and reintervention 0.51%/year (95%CI:0.37-0.71), mostly due to nonstructural valve dysfunction and endocarditis. For a 45-year-old, for example, this translated to an estimated life expectancy of 19 years (general population: 34 years) and lifetime risks of thromboembolism, bleeding and reintervention of 18%, 15%, and 10%, respectively. __Conclusion__ This study demonstrates that outcome after mechanical AVR in non-elderly adults is characterized by suboptimal survival and considerable lifetime risk of anticoagulation-related complications, but also reoperation. Non-elderly adult patients who are facing prosthetic valve selection are entitled to conveyance of evidence-based estimates of the risks and benefits of both mechanical and biological valve options in a shared decision-making process.