Cardiac Magnetic Resonance Imaging Study for Quantification of Infarct Size Comparing Directly Serial Versus Single Time-Point Measurements of Cardiac Troponin T

ObjectivesWe compared single-point cardiac troponin T (cTnT) measurements with parameters from serial sampling during 96 h after acute myocardial infarction with magnetic resonance imaging measured infarct mass.BackgroundContrast-enhanced magnetic resonance imaging (CE-MRI) allows exact quantification of myocardial infarct size. Clinically, measurement of cardiac biomarkers is a more convenient alternative.MethodsThe CE-MRI infarct mass was determined 4 days after primary percutaneous coronary intervention in 31 ST-segment elevation myocardial infarction (STEMI) and 30 non–ST-segment elevation myocardial infarction (NSTEMI) patients. All single-point, peak, and integrated area under the curve (AUC) cTnT values were plotted against CE-MRI infarct mass.ResultsAll single-point and serial cTnT values were significantly higher in STEMI than in NSTEMI (p < 0.01) patients. Except for the admission values, all single-point values on any of the first 4 days, peak cTnT and AUC cTnT were found to correlate comparably well with infarct mass. Among single-point measurements, cTnT on day 4 (cTnTD4) showed highest correlation and performed as well as peak cTnT or AUC cTnT (r = 0.66 vs. r = 0.65 vs. r = 0.69). Receiver-operator characteristic analysis demonstrated that cTnTD4 >0.84 μg/l predicted infarct mass above median as well as peak cTnT >1.57 μg/l or AUC cTnT (receiver-operator characteristic for AUC: 0.839 vs. 0.866 vs. 0.893). However, estimation of infarct mass with cTnTD4, peak cTnT, and AUC cTnT was worse in patients with NSTEMI (r = 0.36, r = 0.5, r = 0.36) than in STEMI (r = 0.75 vs. r = 0.65 vs. r = 0.76).ConclusionsAll single-point cTnTs, except on admission, give a good estimation of infarct size and perform as well as peak cTnT or AUC cTnT. Infarct estimation by single-point measurements, particularly cTnTD4, may gain clinical acceptance because the measurement is easy and inexpensive.