Diagnostic accuracy of heart-type fatty acid–binding protein for the early diagnosis of acute myocardial infarction

Abstract

Objective

The aim of this study was to evaluate the diagnostic efficacy of multiple tests—heart-type fatty acid–binding protein (H-FABP), cardiac troponin I (cTnI), creatine kinase-MB, and myoglobin—for the early detection of acute myocardial infarction among patients who present to the emergency department with chest pain.

Methods

A total of 1128 patients provided a total of 2924 venous blood samples. Patients with chest pain were nonselected and treated according to hospital guidelines. Additional cardiac biomarkers were assayed simultaneously at serial time points using the Cardiac Array (Randox Laboratories Ltd, Crumlin, United Kingdom).

Results

Heart-type fatty acid–binding protein had the greatest sensitivity at 0 to 3 hours (64.3%) and 3 to 6 hours (85.3%) after chest pain onset. The combination of cTnI measurement with H-FABP increased sensitivity to 71.4% at 3 to 6 hours and 88.2% at 3 to 6 hours. Receiver operating characteristic curves demonstrated that H-FABP had the greatest diagnostic ability with area under the curve at 0 to 3 hours of 0.841 and 3 to 6 hours of 0.894. The specificity was also high for the combination of H-FABP with cTnI at these time points. Heart-type fatty acid–binding protein had the highest negative predictive values of all the individual markers: 0 to 3 hours (93%) and 3 to 6 hours (97%). Again, the combined measurement of cTnI with H-FABP increased the negative predictive values to 94% at 0 to 3 hours, 98% at 3 to 6 hours, and 99% at 6 to 12 hours.

Conclusion

Testing both H-FABP and cTnI using the Cardiac Array proved to be both a reliable diagnostic tool for the early diagnosis of myocardial infarction/acute coronary syndrome and also a valuable rule-out test for patients presenting at 3 to 6 hours after chest pain onset.

Introduction

Chest pain is one of the most common complaints in patients presenting to the emergency department (ED). In the United States, this is the second highest reason for admission [1]. Of those admitted, only 10% to 13% have a confirmed acute myocardial infarction (AMI) [1]. In England and Wales, approximately 700 000 present with chest pain to the ED, and two thirds of these are admitted [2]. There are significant challenges with early accurate diagnosis of patients presenting with chest pain of possible cardiac origin because none of the standard diagnostic tests have sufficient diagnostic use to accurately rule out underlying acute coronary syndrome (ACS) in the early stages [3]. Furthermore, there are associated logistic and financial burdens linked to the management of these patients. Inappropriate discharge is associated with a 5-fold increase in mortality and morbidity [4].

The diagnosis of ACS is presently determined by evaluating risk factors, electrocardiographic (ECG) traces, and measurement of cardiac markers. Current biochemical markers used in the diagnosis of ACS include cardiac troponins (cTn), creatine kinase-MB (CK-MB), and myoglobin (MYO). They are limited by either a lack of specificity or a delay of elevation of several hours after symptom onset. Therefore, their clinical use in early diagnosis of AMI is limited. Previous studies have established the success of heart-type fatty acid–binding protein (H-FABP) as an early biochemical marker in the detection of AMI and its use as a prognostic indicator of post-MI recovery [5], [6], [7], [8], [9]. Furthermore, both the European Society of Cardiology (ESC) and National Academy of Clinical Biochemistry [10] have suggested a multimarker approach for the detection of AMI. The Cardiac Array from Randox Laboratories Ltd (Crumlin, United Kingdom) contains the early markers H-FABP and MYO and the late markers cardiac troponin I (cTnI) and CK-MB on a ceramic biochip. The biochip is read using biochip array technology that allows simultaneous measurement of all 4 markers from a small sample volume (50 μL).

The aim of the this study was to determine the diagnostic efficacy of H-FABP with the additional markers present on the Cardiac Array against standard diagnosis using American College of Cardiology (ACC)/ESC guidelines [11], [12] for the early detection of AMI among patients who present to the ED with chest pain.