Platelet Reduction after Aortic Bioprosthesis Implantation: Results from the PORTRAIT Study

Background: Platelet count reduction (PR) is a common but unclear phenomenon that occurs after aortic bioprosthesis valve implantation (bio-AVR). This study aimed to investigate the occurrence and clinical impact of PR in patients receiving stented, rapid deployment (RDV), or stentless bioprostheses. Methods: 1233 adult bio-AVR patients were enrolled. Platelet count variation, early post-operative adverse events, and in-hospital mortality were analysed. Results: 944 patients received a stented valve, an RDV was implanted in 218 patients, and 71 patients had a stentless bioprosthesis. In all groups, the platelet count at discharge was lower than the baseline values (p < 0.001). The percentage of PR was 27% in the stented group, 56% in the RDV group, and 55% in the stentless group. A higher platelet reduction, reaching the minimum platelet value, was observed in the RDV (mean: -30.84, standard error (SE): 5.91, p < 0.001) and stentless (mean: 22.54, SE: 9.10, p = 0.03) groups compared to the stented group. A greater PR occurred as the size of the bioprosthesis increased in RDV (p = 0.01), while platelet count variation was not directly proportional to the stented bioprosthesis size (p < 0.001). PR was not affected by cardiopulmonary bypass (mean: -0.00, SE: 0.001, p = 0.635) or cross-clamp (mean: -0.00, SE: 0.002, p = 0.051) times in any of the groups. RDV subjects experienced more in-hospital adverse events. PR was found to be associated with ischemic strokes in the overall population. Conclusions: Bio-AVR is associated with significant but transient PR. RDV patients more likely experience significant PR and related adverse clinical events. PR is associated with ischemic strokes, regardless of the bioprosthesis type.