Procalcitonin in Infective Endocarditis

Abstract & Commentary

Synopsis: Procalcitonin may be a useful diagnostic marker in suspected IE.

Source: Mueller C, et al. Circulation.2004;109: 1707-1710.

The diagnosis of infective endocarditis (IE) remains a challenge. Thus, these investigators from Basel, Switzerland hypothesized that a marker of systemic bacterial infection such as procalcitonin may help. In 67 consecutive patients with clinical suspicion of IE, a multidisciplinary team applied the Duke criteria to make the diagnosis of IE in 21 patients. Procalcitonin was significantly higher in the IE patients as compared to the others (6.6 vs 0.4 mg/mL, P < .001). The area under the receiver operating curve for procalcitonin was .86 vs .66 for C-reactive protein. The procalcitonin cut-off of 2.3 mg/mL showed a sensitivity of 81%, a specificity of 85%, a negative predictive value of 92%, and a positive predictive value of 72%. Multivariate analysis showed that procalcitonin was the only independent predictor of IE on admission to the hospital (OR, 1.52; CI, 1.07-2.15, P = .02). Mueller and colleagues concluded that procalcitonin may be a useful diagnostic marker in suspected IE.

Comment by Michael H. Crawford, MD

The age of serum markers is upon us. Emergency department and other physicians in a triage capacity love these tests; they are quick, easy and usually have a high negative predictive value. So, if they are negative, the condition under suspicion can confidently be excluded. If the test is positive, it becomes someone else’s problem and the low positive predictive value is of little concern to the triage physician. Procalcitonin seems to be another such test. As Mueller et al point out, it is just as good at diagnosing IE as BNP is for diagnosing heart failure. Heaven help us.

On the other hand, IE is as difficult to diagnose as ever and a negative procalcitonin may stave off a ransesophageal endocardiogram (TEE) in an otherwise low risk patient. Many patients with signs of sepsis have normal cardiac histories, physical examinations and transthoracic echocardiograms because of IV drug use, compromised host defenses, and other illnesses put them at risk for IE despite relatively normal hearts. In such patients TEE may be the only way to make a diagnosis. The procalcitonin test may help direct further diagnostic efforts in these difficult cases.

Michael H. Crawford, MD, Professor of Medicine, Associate Chief of Cardiology for Clinical Programs, University of California San Francisco, is Editor of Clinical Cardiology Alert.