Evaluating possible acute coronary syndrome in primary care: the value of signs, symptoms, and plasma heart-type fatty acid-binding protein (H-FABP). A diagnostic study.

Abstract

Additional diagnostic means could be of added value when evaluating possible acute coronary syndrome (ACS) in primary care. To determine whether heart-type fatty acid-binding protein (H-FABP)-based point-of-care (POC) biomarker testing, embedded in a clinical decision rule (CDR), is helpful to the GP when evaluating possible ACS. A prospective, non-randomised, double-blinded, diagnostic derivation study was undertaken, with a delayed-type cross-sectional diagnostic model among GPs in the Netherlands and Belgium. Signs and symptoms predicting acute myocardial infarction (AMI) or ACS were identified using both logistic regression analysis, and classification and regression trees (CART). Diagnostic values of the POC H-FABP test (cut-off value 4 ng/ml) alone and as part of a CDR were determined. A total of 303 participants (48.8% male) with chest pain or discomfort who had consulted a GP were enrolled. ACS was found in 32 (10.6%) of these 303 patients. For ACS, sensitivity and negative predictive value (NPV) of the POC H-FABP test was 25.8% (95% confidence interval [CI] = 12.5 to 44.9) and 91.6% (95% CI = 87.6% to 94.5%), respectively. The area under the receiver operating curve of the optimal CDR was 0.78 for ACS. Sensitivity of the current H-FABP POC test (cut-off value 4 ng/ml) as a stand-alone test is poor, either owing to limitations of the marker or of the test device. Usability of a CDR derived from these results is doubtful: the number of ACS cases missed by the GP is reduced but, as a consequence, disproportionally more ACS-negative patients are referred.