Mechanical aortic heart valves have an improved long-term survival benefit over biological heart valves for patients aged 50-70 years, according to a new study.
Current international cardiothoracic clinical guidelines advise mechanical aortic valve replacement for patients younger than 50 years and biological valves for those above 65 or 70 years of age.
Between the ages of 50 and 70, decisions rest largely on patient and surgeon preferences. Increasingly, patients in this middle range are now receiving biological prostheses, driven by the rise of transcatheter surgical techniques and the desire to avoid long term anticoagulation. However, uncertainty exists on the long-term outcome data associated with biological aortic valve replacement.
A recent UK study set out to explore this uncertainty around mechanical or biological aortic valve selection for this patient cohort.
The primary endpoint was to compare long-term survival for those receiving either mechanical or biological valves. Secondary endpoints focused on short-term outcomes, reintervention rates and how valve size and patient–prosthesis mismatch influenced long-term results.
Improved long-term survival benefit with mechanical valves
All patients aged between 50 and 70 years who had isolated surgical aortic valve replacement at the Bristol Heart Institute between 1996 and 2023 were included. Data from 1,708 patients were analysed, of whom the majority (69.7%) received a biological valve.
Patients receiving mechanical valves tended to be younger, had a lower incidence of diabetes, and were less likely to have undergone percutaneous coronary intervention. They demonstrated better long-term survival than those who received biological valves, yet reintervention rates did not significantly differ between the two groups.
The long-term survival benefit conferred by mechanical aortic prostheses was especially apparent in smaller valve sizes, with a 19 mm mechanical valve providing better long-term survival than both 19 mm and 21mm bioprosthetic valves, and equivalent to 23 mm bioprosthetic valves.
The authors noted that, based on these results, ‘the risk associated with root enlargement and implanting a larger-sized valve could be avoided’.
The study also found that severe patient-prosthesis mismatch was a significant risk factor for poor long-term survival. Expanding on this, the authors surmised: ‘The reduced survival with 19 mm and 21mm bioprosthetic valves is likely secondary to patient-prosthesis mismatch and the resultant effects.’
Its status as a single-centre study, reliance on retrospectively gathered data and absence of randomisation may contribute to potential biases in this research, the authors noted.
Nevertheless, they considered their findings important for future policy and practice regarding the choice of mechanical versus biological aortic valve replacement. ‘Our study underscores the need for a critical re-evaluation of prosthesis selection strategies in this age group,’ they concluded.
Reference
Chan J et al. Long-term clinical outcomes in patients between the age of 50–70 years receiving biological versus mechanical aortic valve prostheses. Eur J Cardiothorac Surg 2025 Feb 4;67(2):ezaf)33.
