RESUMO
BACKGROUND AND AIM OF THE STUDY: As platelet activation is known to be a side effect of cardiac surgery, recent analyses have been conducted to identify the association between thrombocytopenia and aortic valve replacement (AVR) using a bioprosthesis. The type of bioprosthesis has been indicated as an independent risk factor for a lower postoperative platelet count, an association which has been mainly observed with the Sorin Freedom Solo valve. The study aim was to analyze platelet activation after AVR with two different bioprostheses, the Sorin Freedom SOLO (FS) and the Carpentier-Edwards Magna (CE). METHODS: Thirty-eight consecutive patients undergoing aortic valve surgery were enrolled prospectively and assigned to either the FS group (n = 18) or the CE group (n = 20) according to their clinical evaluation. Five patients who underwent isolated coronary artery bypass graft (CABG) with cardiopulmonary bypass (CPB) were included as a control group. Clinical biochemical parameters (von Willebrand factor (vWF), prothrombin fragments 1+2 (F1+2), P-selectin, and beta-thromboglobulin (beta-TG)) were assessed preoperatively (TO), and at 1 h (T1), 48 h (T2) and seven days (T3) postoperatively. RESULTS: The two groups differed in terms of age (FS 77.3 +/- 7.0 years; CE 65.4 +/- 8.4 years; p < 0.05). Intraoperatively, parameters such as CPB time (FS 106.8 +/- 25.5 min; CE 108.2 +/- 23.4 min, p = NS) and aortic cross-clamp time (FS 78.1 +/- 22.8 min; CE 80.7 +/- 19.4 min, p = NS) were comparable. The platelet count was significantly reduced after FS implantation compared to the other groups. Factors involving platelet activation and blood coagulation activation assessed by means of prothrombin F1+2 (FS: TO = 0.48; T1 = 0.66; T2 = 0.46; T3 = 0.52 nmol/ml versus CE: T0 = 0.38; T1 = 0.68; T2 = 0.41; T3 = 0.49 nmol/ml); P-selectin (FS: T0 = 89.6; T1= 130.4; T2 = 92.6; T3 = 94.3 ng/ml versus CE: T0 = 81.4; T1 = 115.9; T2 = 92.2; T3 = 85.7 ng/ml); and beta-TG (FS: T0 = 6.7; T1 = 17.6; T2 = 8.6; T3 = 7.7 ng/ml versus CE: T0 = 7.1; T1 = 15.6; T2 = 9,1; T3 = 7.5 ng/ml) were not significantly different. CONCLUSION: The previously described phenomenon of enhanced platelet reduction shortly after valve implantation in the FS group compared to another bioprosthesis is likely to be confirmed, but platelet activation should not be considered as the underlying mechanism. Superior (but not significant) preoperative values of biochemical parameters were found in FS versus CE patients, influencing postoperative levels without any variation in the trend pattern. The type of bioprosthesis implanted appeared not to influence platelet and blood coagulation activation.