Thrombocytopenia and perioperative complications after stentless Freedom Solo valve implantation

Freedom Solo (FS) stentless bioprostheses have superior haemodynamic performance compared to stented valves; however, the data of thrombocytopenia after FS implantations is disturbing.

To compare platelet count and perioperative complications between stentless and stented biological valves in patients undergoing aortic valve replacement.

In 29 patients, FS bovine valves (Sorin Group, Saluggia, Italy) were implanted. Platelet counts were analysed before surgery, on the day of operation, on four consecutive postoperative days (POD) as well as at discharge, and compared to 29 control patients with biological stented porcine valves (Labcor Laboratorios TLBP-A Supra). The analysis of the perioperative variables extracorporeal circulation (ECC), aortic cross clamping (XC) and mechanical ventilation times, as well as blood supply, was performed.

Initial platelet counts were comparable in both groups. In the FS group, platelet levels on the four consecutive POD were significantly lower. The lowest platelet value (13 × 10³/μL), related to fatal thrombotic thrombocytopenic purpura, was found in one patient from the FS group. ECC as well as XC and mechanical ventilation times, were significantly longer in the FS group, and more blood transfusions in these patients were required. In multiple regression analysis, ECC and XC times did not correlate with platelet count.

Implantations of FS stentless bioprostheses are related to significantly lower platelet counts. Severe perioperative complications and their relation to thrombocytopenia need further evaluation.