Introduction Heart-type Fatty Acid-Binding Protein (H-FABP) may be useful for early diagnosis of ACS^1,2 and has been associated with increased cardiovascular events. Type 4a procedural myocardial infarction (MI) may occur after percutaneous coronary intervention (PCI).³ Little is known about the use of early biomarkers as predictors of cardiovascular events following elective PCI.

Methods We prospectively evaluated highly sensitive troponin T (hsTnT), H-FABP, troponin I (TnI), creatine kinase MB type (CKMB), myoglobin, glycogen phosphorylase BB (GPBB) and carbonic anhydrase III (CAIII) at 0, 4, 6 and 24 h following elective PCI. Baseline demographic and cardiac risk factors were recorded. The primary endpoint was type 4a MI, diagnosed as a rise of >5 × 99^th upper reference limit (URL) of 14 ng/L (i.e. rise of >70 ng/L) at 6 h if hsTnT was normal at baseline or > 20% from 0 to 6 hrs if hsTnT was >14 ng/L at baseline.³ Patients were followed up at 1 year to assess for major adverse clinical events (MACE); MI, target vessel revascularisation, heart failure, stroke and death.

Results We enrolled 241 patients of whom 32 were excluded due to withdrawal of consent or PCI being cancelled after angiography. A cohort of 209 patients was included in analysis, of whom 144 (68.9%) were male, mean age was 68.8 years, 28 (13.4%) were smokers, 31 (14.8%) were diabetic, 199 (95.2%) had hypercholesterolaemia and 138 (66.0%) had hypertension. Type 4a MI was observed in 37 (17.7%) patients. Comparing those with and without type 4a MI, there was no statistical difference in risk factors (p > 0.05) except for age, (p = 0.015). Median troponin at 6 h was 90.24 ng/L (95% CI 76.56 — 186.41) versus 14.43 ng/L (95% CI 16.37 — 21.26) in the type 4a / non type 4a groups respectively, p=<0.001, Figure 1. Median H-FABP at 4 h was most predictive of type 4a MI (followed by CKMB and myoglobin) with levels of 6.23 mg/L (95% CI 4.38–18.96), versus 2.05mg/L (95% CI 2.23–2.74), p=<0.001, AUC 0.91, Table 1, Figure 2. Results for TnI, CKMB, myoglobin, GBPP and CAIII are shown in Table 1. Multivariate logistic regression (stepwise elimination) showed H-FABP to be most predictive of type 4a MI, p < 0.001. Sensitivity of 4 h H-FABP (>6.32 mg/L) for type 4a MI was 51.5%, specificity 96.1%, positive predictive value (PPV) 73.9%, negative predictive value (NPV) 90.3%, odds ratio (OR) 26.39, relative risk (RR) 7.62. MACE was noted in 6 (2.9%) patients (three MI, two death and one stroke), 3 of which had type 4a MI at index PCI, p = 0.036. Table 2 compares median change in H-FABP and hsTnT from 0 — 6 h in patients who developed MACE at 1 year with CAIII performing best, p = 0.02.

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Abstract 219 Table 1

Summary of biomarker results at 4 h

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Abstract 219 Table 2

Summary of biomarker change from 0–6 h in 1 year MACE and non-MACE patients

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Abstract 219 Figure 1

hsTnT release between type 4a MI (n = 37) and no type 4a MI (n = 172)

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Abstract 219 Figure 2

H-FABP release between type 4a MI (n = 37) and no type 4a MI (n = 172)

Conclusions/implications Median 4 h H-FABP was most predictive of a 6 h hsTnT rise as a consequence of type 4a MI in elective PCI, followed by CKMB and myoglobin. H-FABP and CAIII were independently predictive of MACE at 1 year and MACE was associated with type 4a MI at index PCI.