Incidence of blood culture negative infective endocarditis in patients undergoing cardiac surgery

Blood culture negative infective endocarditis (BCNIE) is a term used for infective endocarditis where no causative microorganism can be detected in blood using routine culture methods. In scientific literature its incidence is approximately 30%, however in some studies it varies from 2.5 to 70%. Data for BCNIE regarding outcome and clinical course are controversial. In this retrospective study we analyze its incidence and possible impact on the outcome. In this study we compiled medical records of 207 patients who underwent cardiac surgery due to infective endocarditis. We assessed the rate of BCNIE incidence and its possible impact on patients’ preoperative condition, laboratory, echocardiographic findings, and short and long-term outcome. Results were analyzed by SPSS 26.0 version. Study was approved by Central Medical Ethics committee of Latvia. The incidence of BCNIE was 44.90 %. Aortic valve was involved in 41.94 %, mitral valve in 22.58 %, aortic and mitral valve in 29.03 % in BCNIE patients. Prosthetic valve infective endocarditis was observed in 19.30 % of cases. Embolic events due to IE were observed in 27.96 % of patients. Mean EuroScore II risk was 6.80%. Intrahospital mortality was 5.38 %. A 3-year mortality reached 31.40 %. When compared to the patient group with known causative microorganism no statistically significant difference was found for both intrahospital and 3-year mortality (p=0.062 and p=0.509). We observed high incidence (44.90 %) of blood culture negative infective endocarditis in this study.Despite of relatively low intrahospital mortality (5.38 %), a 3-year mortality is high (31.40 %).There was no statistically significant difference between blood culture negative infective endocarditis regarding intrahospital and 3-year mortality when compared to the patients with known causative agent.