Abstract 2992: Heart Fatty Acid Binding Protein in Combination With the 80-lead Body Surface Map Improves Early Detection of Acute Myocardial Infarction
Modern high sensitivity assays for cardiac troponin T (cTnT) can detect very low concentrations in the serum and are reducing the need for specific early markers. However, there remains a sub-group of patients who present with ischemic-type chest pain and have a negative cTnT at first medical contact. This group will contain patients at a very early stage of the infarction process. The aim of this research was to assess the usefulness of heart fatty acid binding protein (H-FABP), a novel marker of myocyte ischemia and necrosis, in combination with the 80-lead body surface map (BSM) for further improving early diagnosis of acute myocardial infarction (AMI).
Methods: Consecutive patients presenting to our unit with acute ischemic-type chest pain between 2003–6 were enrolled in this prospective study. At first medical contact blood was sampled for cTnT and H-FABP: in addition, a 12-lead EKG and BSM were recorded. A second cTnT was sampled ≥12 hours after presentation. Peak cTnT ≥0.03μg/L was required for the diagnosis of AMI. Elevated H-FABP was ≥5ng/ml. A cardiologist blinded to both the clinical details and 12-lead EKG interpreted the BSM.
Results: Enrolled were 407 patients (age 62±13 yrs; 70% male). Of these 407, 180 had cTnT ≥0.03μg/L at presentation. AMI occurred in 52/180 (29%). Of those 180 patients, 27 had ST elevation on EKG: 104 had ST elevation on BSM (sensitivity 65%, specificity 85%): 95/180 (53%) had H-FABP elevation. The proportion with elevated H-FABP was higher in the AMI group compared to non-AMI group (42/52 v 53/128, p<0.005). BSM ST-elevation was significantly associated with H-FABP elevation (χ2=67.7, 1df, p<0.001). Of those with initial cTnT <0.03μg/L, the c-statistic for the ROC curve distinguishing AMI from non-AMI using H-FABP alone was 0.644 (95% CI: 0.521– 0.772) and BSM alone was 0.716 (95% CI: 0.638 – 0.793). Using the combination of BSM and H-FABP the c-statistic was 0.812 (95% CI: 0.747– 0.876; p<0.001).
Conclusion: In the important sub-group of patients with acute ischemic-type chest pain who have a normal cTnT at presentation the combination of H-FABP and BSM identifies those with early AMI (c-statistic=0.812, p<0.001), thus allowing earlier institution of reperfusion therapy and secondary prevention.