Surgical procedure
The surgical procedures were done using cardiopulmonary bypass (CPB), and cardioplegic arrest was achieved using a cold crystalloid cardioplegic solution. Standard median sternotomy, upper mini-sternotomy through the fourth intercostal space or anterior mini-thoracotomy were used for the surgical approach. The following mechanical prostheses were used: St. Jude Regent, St. Jude Masters (Abbott, Chicago, IL), ATS Open Pivot (Medtronic, Minneapolis, MN), ONX (CryoLife Inc., Kennesaw, GA) and Carbomedics (LivaNova, London, UK). The biological prostheses used in the study were as follows: Hancock (Medtronic, Minneapolis, MN), Epic, Trifecta (Abbott, Chicago, IL), Crown (LivaNova, London, UK), Solo Smart (LivaNova, London, UK) and sutureless Perceval S valve (LivaNova, London, UK). The choice of the implant procedure was made according to the current guidelines and the surgeon’s discretion alongside the fully informed patient.