Abstract 2832: Which Cardiac Marker is Most Useful to Predict Final Infarct Size and Cardiac Function Following Primary Percutaneous Coronary Intervention For Acute Myocardial Infarction?
Background: Assessment of cardiac biomarker release has been traditionally used to estimate the size of myocardial damage after acute myocardial infarction (AMI). However, the significance of cardiac biomarkers in the setting of primary percutaneous coronary intervention (PCI) has not been systematically studied in a large patient cohort. We evaluated the usefulness of serial and single time-point measures of various cardiac biomarkers (creatine kinase (CK), CK-MB, troponin T and I) in predicting infarct size and left ventricular ejection fraction (LVEF) after primary PCI.
Methods: EVOLVE (Evaluation of MCC-135 for Left Ventricular Salvage in AMI) was a randomized double-blind, placebo-controlled trial comparing the efficacy of intracellular calcium modulator as an adjunct to primary PCI in patients with first large AMI. Levels of cardiac biomarkers (CK, CK-MB mass, troponin T and I) were determined in 375 patients at baseline before PCI and 2, 4, 12, 24, 48 and 72 hours thereafter. Single photon emission computed tomography imaging was performed to measure infarct size and LVEF on day 5.
Results: Area under curve and peak concentrations of all cardiac markers: CK, CK-MB mass, troponin T and troponin I were significantly correlated with myocardial infarct size and LVEF determined on day 5 (Spearman correlation, all P<0.001; Table⇓). Troponin I, however provided the best predictor and a single measure at 72 hr was a strong indicator of both infarct size and LVEF. Using receiver operator characteristics curve, troponin I cutoff value of >55 pg/mL at 72 hr has 90% sensitivity and 70% specificity for detection of large infarct size≥10% (c=0.88; P<0.001).
Conclusions: Plasma levels of CK, CK-MB, troponin T and troponin I remain useful predictors of infarct size and cardiac function in the era of primary PCI for AMI. A single measurement of circulating troponin I at 72 hours can provide an effective and convenient indicator of infarct size and LVEF in clinical practice.