An unexpected risk factor for early degeneration of biological aortic valve prostheses

Background. An alarming rate of early failure has been recently reported for the LivaNova (previously Sorin) Mitroflow (LivaNova, London, UK) bioprosthesis. Here, we aimed at verifying if this possible underperformance is confirmed in a large, single-center experience and identifying the risk factors associated with early deterioration. Methods. In all, 459 Mitroflow valves have been implanted from July 2009 to December 2013 (patients’ mean age 73 years; 204 women). Surviving patients have undergone yearly clinic and echocardiographic followup. Dysfunction was defined as moderate if the mean gradient was more than 30 mm Hg or severe if it exceeded 40 mm Hg. The population was divided on the basis of a dimensional mismatch, the model of the prosthesis (LX or DL: follow-up to 4 years), and patient’s age at the time of implantation. Results. Cumulative freedom from moderate valve dysfunction was 81% ± 3% at 60 months. It was lower with patient-prosthesis mismatch (71% ± 5% versus 92% ± 3%; p [ 0.0065) and with the more recent DL model (at 42 months: 78% ± 6% versus 96% ± 2%; p < 0.0001). Cumulative freedom from severe dysfunction was 93% ± 2% at 5 years. Again, it was inferior among patients with a mismatch (86% ± 4% versus 100%; p [ 0.0013) and for the DL model (42 months: 92.5% ± 3% versus 98.5% ± 1%; p [ 0.0309). Smaller prostheses showed higher rates of early degeneration. Conclusions. The LivaNova Mitroflow valve appears to be prone to early deterioration. Smaller size prostheses should be used cautiously and avoided with patient-prosthesis mismatch. The DL model anti calcification treatment seems unable to prevent early degeneration, and possibly contributes to even earlier failure.