Absence of visible infarction on cardiac magnetic resonance imaging despite the established diagnosis of myocardial infarction by 4th Universal Definition of Myocardial Infarction.

AIMS: Myocardial scarring due to acute myocardial infarction (AMI) can be visualized by late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) imaging. However, a recent study revealed a group of Type 1 AMI patients with undetectable myocardial injury on LGE. This study aims to describe these cases in detail and explore possible explanations for this new phenomenon. METHODS AND RESULTS: A total of 137 patients diagnosed with either ST-elevation myocardial infarction (STEMI) or non-ST-elevation myocardial infarction (non-STEMI) diagnosed according to the 4th Universal Definition of Myocardial Infarction underwent LGE-CMR after invasive coronary angiography. Fourteen of them (10.2%) showed no LGE and were included in the final study population. Most patients presented with acute chest pain, 3 patients were diagnosed as STEMI, and 11 as non-STEMI. Peak high-sensitive cardiac troponin T ranged from 45 to 1173 ng/L. A culprit lesion was identified in 12 patients. Severe coronary stenoses were found in five patients, while seven patients had subtotal to total coronary artery occlusion. Percutaneous coronary intervention was performed in 10 patients, while 2 patients required coronary artery bypass grafting and no intervention was required in 2 patients. Cardiac magnetic resonance was performed 30 (4-140) days after the initial presentation. Most patients showed preserved left ventricular ejection fraction on CMR. No alternative reasons for the rise/fall of high-sensitive cardiac troponin T were found. CONCLUSION: The absence of LGE on CMR in patients with Type 1 AMI is a new finding. While insufficient spatial resolution of LGE imaging, delayed CMR performance, spontaneous reperfusion, and coronary collaterals may provide some explanations, further investigations are required to fully understand this phenomenon.

Correlation of serial high-sensitivity cardiac Troponin T values to infarct mass determined by cardiac magnetic resonance imaging: a validation study.

AIM: To validate correlations between contrast-enhanced magnetic resonance imaging (CE-MRI) infarct mass and high-sensitivity cardiac Troponin T (hs-cTnT) values at different time points in patients with confirmed acute myocardial infarction (AMI). METHODS AND RESULTS: Patients presenting with AMI and with available CE-MRI between 1 January 2018 and 31 December 2020 were included. Correlation coefficients between hs-cTnT on admission, after 24, 48, 72, and 96 h, and peak hs-cTnT values and CE-MRI infarct mass were calculated. Correlations between hs-cTnT and CE-MRI infarct mass were compared with those of a third generation cTnT assay from a previously published study of our group. A total of 137 patients were included for the present analysis. Median CE-MRI infarct mass was 12,5 g [95% confidence interval (CI): 9.8-16.2 g]. Hs-cTnT values and infarct mass correlated well at all time points including admission (r = 0.474, 95% CI: 0.331-0.560, P < 0.0001), 24 h (r = 0.508, 95% CI: 0.370-0.625, P < 0.0001), 48 h (r = 0.547, 95% CI: 0.404-0.664, P < 0.0001), 72 h (r = 0.489, 95% CI: 0.320-0.628, P < 0.0001), 96 h (r = 0.509, 95% CI: 0.330-0.653, P < 0.001) including peak hs-cTnT values (r = 0.547, 95% CI: 0.416-0.656, P < 0.0001), and maximum absolute delta changes within 96 h (r = 0.507, 95% CI: 0.369-0.622, P < 0.001). Correlations of the third generation assay could be confirmed for hs-cTnT at all time points. A superior correlation with CE-MRI infarct mass was observed for hs-cTnT values on admission. CONCLUSION: Hs-cTnT values at different time points correlate well with CE-MRI infarct mass. Correlations of admission hs-cTnT values are superior to those of a third generation assay.