Prevalence and prognostic value of thrombocytopenia in aortic valve replacement surgery: bioprosthesis versus mechanical prosthesis

Abstract Background Thrombocytopenia is a frequent complication of valve surgery, and is associated with different postoperative outcomes. Concern has recently arisen about thrombocytopenia following aortic valve replacement (AVR), as some authors have reported increased postoperative thrombocytopenia with certain biological aortic valves. In adittion, it is unclear whether thrombocytopenia predicts mortality in this type of surgery. Purpose The aim of this study was to determine the prevalence and prognostic value of thrombocytopenia in biological and mechanical aortic valve replacement. Methods The study was an observational analysis of patients undergoing AVR with or without associated coronary artery bypass grafting (CABG) at a single center between October 2014 and October 2023. Cardiac Surgery database was computerized and prospectively completed. Preoperative and first 4 days postoperative platelet counts were analyzed. Thrombocytopenia was defined as platelet count < 100 × 10³/mm³. To obtain comparable populations, a propensity score matching analysis was performed. Results A total of 1,197 patients underwent AVR with (n = 494) or without CABG (n = 703). Patients received either a mechanical prosthesis (n = 320), or a biological prosthesis (n = 877). The mean population age was 68 years (SD 6), with the majority being male (68%). Univariate analysis of the baseline characteristics of both groups of patients showed that they were not comparable. A risk-adjusted subanalysis was performed according to a propensity score (n=278). The nadir of bioprostheses was on the third postoperative day with an average of 93.8 × 10³/mm³, while in mechanical prostheses was also on the same day but with an average of 114.7 × 10³/mm³ (p: 0.001). (Figure 1) Bioprosthesis implantation was significantly associated with a higher prevalence of thrombocytopenia (72.7% vs. 45.3%, p<0.001). The presence of postoperative thrombocytopenia has been associated with higher in-hospital mortality (6.7% vs. 0.9%, p=0.019); but not with other postoperative complications. (Figure 2) Conclusions Patients undergoing AVR with bioprostheses had a significantly higher prevalence of thrombocytopenia, and also lower platelet counts than mechanical prothesis within the first 4 postoperative days. Thrombocytopenia was associated with higher in-hospital mortality in a risk score-adjusted population.Platelet counts after AVROutcomes according to platelet count