Objective: Despite the superiority of mitral valve repair, surgical mitral valve replacement (SMVR) remains an important intervention for patients with valve stenosis, infective endocarditis and complex mitral valve degeneration. There has been an increasing popularity in the worldwide use of biological valves due to the avoidance of long-term anti-coagulation and recent advancements in transcatheter techniques. We aim to evaluate the trend, early clinical outcomes and the choice of prostheses use in isolated SMVR over a 23 years period in the United Kingdom. Methods: All patients (n = 13,147) who underwent elective or urgent isolated SMVR from March 1996 to April 2019 were identified from the National Adult Cardiac Surgery Audit database. Trends in clinical outcomes, predicted/observed mortality of patients and the utilization of biological prostheses across 5 different age groups: <50, 50-59, 60-69, 70-79 and >= 80 years old were investigated. Early clinical outcomes associated with the use of mechanical and biological mitral valve prostheses in patients between the age of 60-70 years old were analysed. Results: The number of isolated SMVR performed has remained stable with approximately 600 cases annually since 2010. The in-hospital/30-day mortality rate has decreased from 7.41% (1996) to 3.92% (2018), despite the EuroScore II increasing from 1.42% in 1996 to 2.43% in 2018. Biological prostheses usage increased across all age group, and particularly in the 60-69 and 70-79 group, from 17.86% and 53.85% in 1996 to 48.85% and 82.38% in 2018, respectively. The use of mechanical prostheses was reduced in patients between the age of 50-59 from 100% in 1996 to 80.65% in 2018. There were no differences in short term outcomes among patients aged 60-70 years who received either a biological or mechanical prostheses. Conclusion: There has been a significant reduction in surgical mitral valve replacement early in-hospital mortality, despite an observed increase in the risk profile of patients over 23 years. A shifting trend in valve replacement choices was observed with a rise in the use of biological prostheses, particularly within the 60-69 and 70-79 age group. Early in hospital outcomes for patients aged 60-70 were not determined by the implanted valve type.
