Usefulness of Serum Procalcitonin as a Markerfor Coexisting Infection in Patients With Acute Myocardial Infarction

A significant proportion of patients with acute myocardial infarction (AMI) also present with clinical manifestations of inflammatory response, which may be confused with a concomitant infection. This leads to a dilemma regarding the empiric use of antibiotics. We explored if serum procalcitonin (PCT), which is known to be elevated in bacterial infections, may be utilized to rule-out bacterial infection in AMI patients. In this prospective, single center study, PCT was collected within 48 hours from AMI patients. Patients' demographic, clinical, and laboratory data were collected prospectively. Two experienced infectious diseases specialists blinded to the PCT results independently determined the presence of infection in every patient. Sensitivity, specificity, positive predictive value, negative predictive value, and the area under the receiver operating characteristic curve were calculated to determine the accuracy of PCT, fever, white blood cell (WBC) count, and C-reactive protein (CRP) levels for the diagnosis of the infection. The analysis included 230 AMI patients (age 63.0 ± 13.0 years) of whom 36 (15.6%) had coexisting infections. The best cutoff for PCT as a differentiating marker between patients with and without coexisting infection was 0.09 ng/dl (sensitivity 94.4%, specificity 85.1%, area under the curve 0.94). PCT outperformed CRP, WBC, and fever for diagnosing infection. In conclusion, compared with CRP, fever, and WBC, serum PCT had a better performance in differentiating infected from noninfected AMI patients and thus should be considered as an adjunct test when facing the dilemma of initiating empiric antibiotic in AMI patient demonstrating inflammatory signs.