Predicting microvascular obstruction with cardiac troponin T after acute myocardial infarction: a correlative study with contrast-enhanced magnetic resonance imaging.

BACKGROUND: The presence of microvascular obstruction (MVO) is associated with more severely impaired left ventricular function and adverse prognosis. The aim of this study was to evaluate whether a single cardiac troponin T-value (cTnT) was able to predict the presence of MVO and whether cTnT is an independent predictor of MVO as compared to usual risk factors. STUDY DESIGN AND METHODS: Sixty-one consecutive patients with reperfused ST-elevation myocardial infarction (STEMI) were enrolled in the study. cTnT was measured serially at admission and after 24, 48, 72 and 96 h. Contrast-enhanced cardiac magnetic resonance imaging (CE-MRI) was performed on a 1.5T MR-scanner 4 +/- 1 days after STEMI. RESULTS: cTnT-time concentration kinetics in the presence of MVO differs from cTnT release in the absence of MVO showing a higher peak and a slower release. At single point measurement 24 h-cTnT correlates at least as well with the presence of MVO (P < 0.001) as peak cTnT (P = 0.0016) and sampling over 96 h (P < 0.001). Using ROC analysis, at single measurement a cTnT concentration >2.52 microg/l at 24 h was a predictor for MVO (AUC 0.91) with a sensitivity of 100% and a specificity of 80% with a positive predictive value of 76% and a negative predictive value of 100%. In multivariate regression analysis 24 h-cTnT remained independent predictor for MVO. CONCLUSIONS: In STEMI, a single 24 h-cTnT value is an independent predictor for MVO and a convenient and inexpensive way to help define this important risk parameter in clinically routine.

Strain-encoded cardiac MR during high-dose dobutamine stress testing: comparison to cine imaging and to myocardial tagging.

PURPOSE: To investigate regional strain response during high-dose dobutamine stress cardiac magnetic resonance imaging (DS-CMR) using myocardial tagging and Strain-Encoded MR (SENC). MATERIALS AND METHODS: Stress induced ischemia was assessed by wall motion analysis, by tagged CMR and by SENC in 65 patients with suspected or known CAD who underwent DS-CMR in a clinical 1.5 Tesla scanner. Coronary angiography deemed as the standard reference for the presence or absence of CAD (> or =50% diameter stenosis) in all patients. RESULTS: SENC and conventional tagging detected abnormal strain response in six and five additional patients, respectively, who were missed by cine images and proved to have CAD by angiography (P < 0.05 for SENC versus cine, P = 0.06 for tagging versus cine and p = NS for SENC versus tagging). On a per-vessel level, wall motion analysis on cine images showed high specificity (95%) but moderate sensitivity (70%) for the detection of CAD. Tagging and SENC yielded significantly higher sensitivity of 81% and 89%, respectively (P < 0.05 for tagging and P < 0.01 for SENC versus wall motion analysis, and p = NS for SENC versus tagging), while specificity was equally high (96% and 94%, respectively, P = NS for all). CONCLUSION: Both the direct color-coded visualization of strain on CMR images and the generation of additional visual markers within the myocardium with tagged CMR represent useful adjuncts for DS-CMR, which may provide incremental value for the detection of CAD in humans. J. Magn. Reson.

Cardiac magnetic resonance imaging study for quantification of infarct size comparing directly serial versus single time-point measurements of cardiac troponin T.

OBJECTIVES: We 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. BACKGROUND: Contrast-enhanced magnetic resonance imaging (CE-MRI) allows exact quantification of myocardial infarct size. Clinically, measurement of cardiac biomarkers is a more convenient alternative. METHODS: The 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. RESULTS: All 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 microg/l predicted infarct mass above median as well as peak cTnT >1.57 microg/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). CONCLUSIONS: All 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.

Relative role of NT-pro BNP and cardiac troponin T at 96 hours for estimation of infarct size and left ventricular function after acute myocardial infarction.

BACKGROUND: N-terminal brain-type natriuretic peptide (NT-pro BNP) and cardiac troponin T (cTnT) after acute myocardial infarction (AMI) have proven useful for prediction of prognosis and may be valuable for assessment of left ventricular function and infarct size. The aim of the present study was to correlate infarct size and left ventricular function determined by cine and late gadolinium enhanced CMR with plasma levels of TNT and NT-pro BNP levels after AMI. METHODS: We studied 44 patients (pts) with first ST- and non-ST-segment elevation myocardial infarction (STEMI=23 pts.,NSTEMI=21 pts.). We measured NT-pro BNP and cTnT on a single occasion at 96 hours after onset of symptoms. RESULTS: There was a moderate inverse correlation between NT-pro BNP and LV-EF in STEMI (r=-0.67, p=0.0009) and NSTEMI (r=-0.85, p<0.0001). Likewise, cTnT showed a significant inverse correlation with LV-EF in STEMI (r=-0.54, p=0.014) but not in NSTEMI. With cTnT there was a strong linear correlation with infarct mass and relative infarct size in STEMI (r=0.92, p<0.0001) and NSTEMI (r=0.59, p<0.0093). NT-pro BNP demonstrated a good relationship with infarct mass (r=0.79, p<0.0001) and relative infarct size (r=0.75, p<0.0001) in STEMI, but not in NSTEMI. CONCLUSION: A single NT-pro BNP and cTnT value at 96 hours after onset of symptoms proved useful for estimation of LV-EF and infarct size. In direct comparison, NT-pro BNP disclosed a better performance for estimation of LV-EF whereas cTnT was superior for assessment of infarct mass and relative infarct size, suggesting an implementation of a dual marker strategy for diagnostic and prognostic work-up.

Cardiac troponin T at 96 hours after acute myocardial infarction correlates with infarct size and cardiac function.

OBJECTIVES: In clinical practice, myocardial infarct size can be estimated non-invasively by nuclear imaging techniques or contrast-enhanced magnetic resonance imaging (CE-MRI). Due to limited availability and high costs, serologic tests are frequently used as an alternative. BACKGROUND: We examined the ability of a single value of cardiac troponin T (cTnT) 96 h after onset of ST-/non-ST-segment elevation myocardial infarction (STEMI/NSTEMI) to estimate absolute infarct mass. METHODS: Functional and CE-MRI were conducted on a 1.5-T whole-body system 4 days after STEMI/NSTEMI using gadolinium (0.2 mmol/kg/bw). Infarct sizes were measured employing a specified software (Philips Medical Systems, Best, the Netherlands) and correlated with TnT measurements 96 h after onset of STEMI/NSTEMI. RESULTS: We enrolled 23 STEMI and 21 NSTEMI patients. Median time delay from onset of symptoms to balloon angioplasty was 6.25 and 9.9 h for STEMI/NSTEMI patients, respectively. Contrast-enhanced magnetic resonance imaging (median 4 days) revealed an absolute mean infarct size of 16.2 g (7.7 to 30.1 g) with a mean ejection fraction of 58% (53% to 63%) and mean stroke volume of 84 ml (75 to 107 ml). Absolute infarct sizes and median cTnT values were larger in STEMI than in NSTEMI (29.3 g [interquartile range (IQR) 16.0 to 53.0] and 1.88 microg/l [IQR 0.7 to 2.57] vs. 8.8 g [IQR 3.3 to 16.4] and 0.83 microg/l [IQR 0.4 to 1.3], both p < 0.02). Linear regression analysis was excellent for STEMI (r = 0.910) and moderate albeit still significant for NSTEMI (r = 0.575). CONCLUSIONS: A single 96-h cTnT value provides an accurate estimate of absolute infarct mass in myocardial infarction. The ability to quantify and the potential to distinguish effects of novel drug regimens on infarct size make cTnT attractive for routine practice and as a clinical end point.