Procalcitonin in 759 Patients Clinically Suspected of Infective Endocarditis

BackgroundDiagnostic delay contributes to high morbidity and mortality in infective endocarditis. A readily available diagnostic marker of infective endocarditis is desirable. S-procalcitonin has been proposed as a candidate, but data on its yield are conflicting. We tested its diagnostic value in a large population of patients seen in a tertiary center.MethodsThis prospective study included 759 consecutive patients referred for echocardiographic examination on clinical suspicion of infective endocarditis. Transthoracic echocardiography was followed by immediate transesophageal examination, and a blood sample was obtained for procalcitonin analysis. Infective endocarditis was diagnosed by an interdisciplinary team and confirmed according to the Duke criteria. The team was unaware of the results of procalcitonin analyses.ResultsInfective endocarditis was present in 147 patients (19%). Procalcitonin was higher in these patients than in those in whom infective endocarditis was rejected (median, 0.21 ng/mL vs. 0.13 ng/mL; P <.0005). Multivariate analysis identified significant independent determinants of high procalcitonin: blood culture with endocarditis-typical microorganisms (odds ratio [OR], 2.81), temperature ≥38°C (OR, 2.61), symptoms ≤5 days (OR, 2.39), immunocompromised status (OR, 1.74), and male gender (OR, 1.61). Tests at various procalcitonin thresholds yielded an acceptable sensitivity of 95% at 0.04 ng/mL, but specificity was only 14%. Only 12% had procalcitonin below this threshold, which might justify postponement of further examinations for infective endocarditis.ConclusionsProcalcitonin was significantly higher in patients with infective endocarditis than in patients without infective endocarditis and bacteremia with endocarditis-typical organisms was the strongest independent determinant of high procalcitonin. The clinical importance of this is questionable, because a suitable procalcitonin threshold for diagnosing or excluding infective endocarditis was not established.