Background: The use of prosthetic valves and intracardiac devices has steadily increased in recent years. In this group of patients with prosthetic valves or intracardiac devices, infective endocarditis could not be easily diagnosed, and in general, infective endocarditis can be missed in many patients. The purpose of this study was to evaluate the diagnostic performance of clinical, laboratory, and imaging parameters in a group of patients with pre-diagnosis of infective endocarditis.

Methods: Ninety-four patients diagnosed with prosthetic valve or intracardiac device endocarditis during 2008-2019 were included in the study. The patients’ data were evaluated according to modified Duke criteria, and the data of the patients who were diagnosed with and without a definitive infective endocarditis were compared accordingly.

Results: Values of procalcitonin (P <.001), leukocytes (P =.004), C-reactive protein (P <.001), sedimentation (P <.001), and maximal vegetation size (P =.012) were found to be significant in the diagnosis of IE. Criteria to determine definitive IE included a C-reactive protein level of 105 mg/dL or higher, 77% sensitivity, 75% specificity, 60% positive predictive value, and 87% negative predictive value. In particular, a C-reactive protein level of ≥105 mg/dL was found to positively indicate the diagnosis of definitive infective endocarditis by 10 times (odds ratio = 10; 95% CI: 3.6-27.8, P <.001). In a multiple logistic regression
analysis, the C-reactive protein level was found to be the best independent predictor of definitive infective endocarditis in this population.

Conclusion: In cases of prosthetic valve and intracardiac devices endocarditis where prediagnosis
is difficult to confirm, measuring C-reactive protein levels is a reliable, strong, and simple parameter for definitive infective endocarditis diagnosis.