Abstract 349: Elevated Troponin: How Well Does it Predict a Diagnosis of Acute Coronary Syndrome?
Background: Cardiac troponins are highly sensitive for detection of myocardial necrosis and considered the reference standard for diagnosing acute coronary syndromes (ACS). Due to high sensitivity and widespread use in patients with low likelihood of ACS, the positive predictive value (PPV) of elevated troponin for determining ACS may be limited.
Methods: From 2006-2007, all patients with elevated troponin ( > 0.03 ng/dL) at our facility were evaluated by an attending cardiologist within 24 hours of a positive troponin in order to determine the presence or absence of ACS. Patients were tracked during their hospitalization with data gathered prospectively in a database maintained for quality purposes. We conducted a cross sectional investigation of patients in this database to ascertain the PPV of elevated troponin for diagnosing ACS. Baseline characteristics and symptoms for patients with and without ACS were compared. Multivariate logistic regression was performed to determine correlations between the diagnosis of ACS and patient characteristics, symptoms and other objective findings.
Results: 1018 patients were included. Mean initial troponin value was higher for patients with ACS (0.42 versus 0.13, p < 0.0001). Overall, the PPV of elevated troponin for diagnosing ACS was only 29.8%. The PPV varied widely depending on the initial symptom reported (highest, chest pain 48.8%; lowest, low energy 2.3%). In multivariate logistic regression, few patient characteristics were correlated with ACS, including smoking (odds ratio [OR] 4.36, 95% confidence interval [CI] 2.45-7.76, p < 0.0001) and hyperlipidemia (OR 1.62, 95% CI 1.16-2.27, p=0.005). New electrocardiogram changes (OR 5.43, 95% CI 3.49-8.46, p<0.0001) and troponin value greater than 10 fold above upper limit of normal (OR 2.79, 95% CI 1.12-6.96, p=0.028) were correlated with ACS. The only symptom correlated with ACS was chest pain (OR 5.00, 95% CI 3.51-7.13).
Conclusion: Elevated troponin alone has weak PPV for diagnosing ACS when adjudicated by an attending cardiologist. Troponin elevations were observed with various presenting symptoms, and the PPV was dependent on chief complaint. New electrocardiogram changes, level of troponin elevation, chest pain, and smoking were strongly correlated with the diagnosis of ACS.
Author Disclosures: L.A. Burke: None. N. Agarwal: None. C. Schmalfuss: None. D.E. Winchester: None.
- © 2014 by American Heart Association, Inc.