BackgroundFurther research is needed to assess the risk and prognosis after valve replacement surgery in elderly patients. This study aims to assess the prognostic value of platelet levels following valve replacement in elderly patients.MethodsA retrospective analysis was conducted on 3814 elderly individuals who underwent valve replacement surgery, categorized into quartiles based on postoperative platelet levels. Univariate and multiple regression analysis were used to assess the risk factors associated with postoperative platelet levels and in-hospital death.The Receiver Operating Characteristic (ROC) curve was utilized to establish the postoperative platelet level threshold indicative of in-hospital mortality risk, while the Kaplan-Meier curve compared the one-year postoperative survival among patients with differing postoperative platelet levels.ResultsThe low postoperative platelet levels group had a higher incidence of massive bleeding (> 400 ml), necessitating platelet transfusion and prolonged cardiopulmonary bypass during surgery (P < 0.001). However, postoperative occurrences of heart failure and stroke did not achieve statistical significance (P > 0.05). Multivariate regression analysis disclosed an association between postoperative platelet levels and in-hospital death (OR: 2.040, 95% CI: 1.372–3.034, P < 0.001). Over the one-year follow-up, patients with low platelet levels postoperatively had poorer overall survival than patients with higher platelet levels (P < 0.001)ConclusionPostoperative platelets can serve as a prognostic indicator after valve surgery in elderly patients as a simple and easily available biochemical indicator. Enhanced monitoring and management postoperative platelet level in the elderly may be beneficial to improve the survival outcome of patients