Abstract
We used multi-parametric cardiovascular magnetic resonance (CMR) mapping to interrogate the myocardium following ST-segment elevation myocardial infarction (STEMI). Forty-eight STEMI patients underwent CMR at 4 ± 2 days. One matching short-axis slice of native T1 map, T2 map, late gadolinium enhancement (LGE), and automated extracellular volume fraction (ECV) maps per patient were analyzed. Manual regions-of-interest were drawn within the infarcted, the salvaged and the remote myocardium. A subgroup analysis was performed in those without MVO and with ≤75% transmural extent of infarct. For the whole cohort, T1, T2 and ECV in both the infarcted and the salvaged myocardium were significantly higher than in the remote myocardium. T1 and T2 could not differentiate between the salvaged and the infarcted myocardium, but ECV was significantly higher in the latter. In the subgroup analysis of 15 patients, similar findings were observed for T1 and T2. However, there was only a trend towards ECVsalvage being higher than ECVremote. In the clinical setting, current native T1 and T2 methods with the specific voxel sizes at 1.5 T could not differentiate between the infarcted and salvaged myocardium, whereas ECV could differentiate between the two. ECV was also higher in the salvaged myocardium when compared to the remote myocardium.
Highlights
Myocardial salvage index (MSI) is considered a more sensitive measure for assessing the efficacy of a cardioprotective strategy than an absolute reduction in myocardial infarct (MI) size, as it normalizes the reduction in MI size to the area-at-risk (AAR)[1,2,3]
In order to clarify whether the infarcted myocardium can be distinguished from the salvaged myocardium in the acute setting, we used multiparametric Cardiovascular magnetic resonance imaging (CMR) with native T1 maps, T2 maps and automated extracellular volume fraction (ECV) mapping to interrogate the infarcted and salvaged myocardium in patients shortly after ST-segment elevation myocardial infarction (STEMI) reperfused by primary percutaneous coronary intervention (PPCI)
A subgroup analysis was performed in those patients without late microvascular obstruction (MVO) and with ≤75% transmural extent of infarct (to minimize partial volume effects when drawing the regions of interest (ROI) in the salvaged myocardium)
Summary
Myocardial salvage index (MSI) is considered a more sensitive measure for assessing the efficacy of a cardioprotective strategy than an absolute reduction in myocardial infarct (MI) size, as it normalizes the reduction in MI size to the area-at-risk (AAR)[1,2,3]. Cardiovascular magnetic resonance imaging (CMR) is considered the reference standard technique for MI size quantification[5,6,7] It can provide information on the edema-based AAR using T2-weighted imaging[3,8,9], T2 mapping[10,11], T1 mapping[11,12], early gadolinium enhancement[13], or post-contrast steady-state-free-precession www.nature.com/scientificreports/. If we were able to differentiate between the infarcted and salvaged myocardium using native T1 and T2 mapping, we could potential quantify both the AAR and MI size accurately without contrast on these maps by applying different thresholds, which would significantly shorten scan time for these patients and expand the availability to those with contraindications to the gadolinium chelate. In order to clarify whether the infarcted myocardium can be distinguished from the salvaged myocardium in the acute setting, we used multiparametric CMR with native T1 maps, T2 maps and automated extracellular volume fraction (ECV) mapping to interrogate the infarcted and salvaged myocardium in patients shortly after ST-segment elevation myocardial infarction (STEMI) reperfused by primary percutaneous coronary intervention (PPCI)
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