Objective:To evaluate the relationship between preoperative sarcopenia and severe pulmonary complications after cardiac surgery in elderly patients.Methods:Elderly patients undergoing elective open heart surgery in our hospital were collected and divided into non-sarcopenia group and sarcopenia group, according to the diagnostic criteria updated and revised by the Asian Sarcopenia Working Group in 2019. The outcome measure was the development of severe postoperative pulmonary complications (PPCs). The general information of patients and various indexes of surgical conditions were recorded. Risk factors for severe PPCs were identified by multivariate logistic regression analysis. The accuracy of sarcopenia score, American Society of Anesthesiologists (ASA) Physical Status classification, and combination of ASA Physical Status classification and sarcopenia score in predicting severe PPCs was assessed using the receiver operating characteristic curve.Results:A total of 158 patients were finally enrolled, including 36 patients with sarcopenia (22.7%), and the incidence of severe PPCs was 22.2%. Multivariate logistic regression analysis showed that ASA classification, sarcopenia, and duration of surgery were independent risk factors for severe PPCs after cardiac surgery in elderly patients ( P<0.05), and the risk of severe PPCs was approximately 3.21 times higher in sarcopenic patients than in non-sarcopenic patients. The area under the receiver operating characteristic curve of sarcopenia score, ASA Physical Status classification, and ASA Physical Status classification combined with sarcopenia score in predicting severe PPCs were 0.686 (95% confidence interval [ CI] 0.607-0.757), 0.603 (95% CI 0.522-0.680), and 0.714 (95% CI 0.637-0.783), respectively. Conclusions:Preoperative sarcopenia is an independent risk factor for severe PPCs after cardiac surgery in elderly patients, and the preoperative sarcopenia in combination with ASA Physical Status classification in predicting severe PPCs has a certain accuracy.