Timing of cardiovascular magnetic resonance imaging after acute myocardial infarction: effect on estimates of infarct characteristics and prediction of late ventricular remodelling
© Mather et al; licensee BioMed Central Ltd. 2011
Published: 2 February 2011
Cardiovascular Magnetic Resonance (CMR) permits a comprehensive assessment of infarct characteristics following acute myocardial infarction (AMI). The pathophysiological remodelling processes associated with AMI evolve over time and as such, the optimal acute imaging time point to predict medium-term surrogates for outcome has not been established.
This study aimed to define the evolution of myocardial oedema, haemorrhage, microvascular obstruction (MVO) and infarct size by CMR, post-AMI. Secondly, we aimed to assess whether CMR data acquired at ‘day 2’ post-AMI are stronger predictors of infarct size and left ventricular (LV) function, measured at 3 months follow up, than data acquired at ‘1 week’.
Fifty-seven patients were recruited with first presentation ST elevation myocardial infarction (STEMI) treated successfully with primary percutaneous coronary intervention. Cine, T2- weighted and late gadolinium enhancement CMR imaging were performed at days 2, 7, 30 and 90 after index presentation.
Infarct size and extent of myocardial oedema decreased significantly between ‘day 2’ and ‘1 week’ (mean %LV-scar (SD) 27.2 (13.9) vs. 21.6 (14.1), p<0.001 and %LV-AAR (Area At Risk) (SD), 37.9 (15.2) vs. 32.3 (14.3), p=0.003). These changes were accompanied by a significant improvement in LV ejection fraction (%LVEF (SD), 41.7 (9.6) vs. 44.6 (10.1), p<0.001). CMR data acquired at ‘1 week’ were better predictors of LVEF and infarct size at ‘3 months’ than data collected at ‘day 2’. The myocardial salvage index (MSI) ((AAR- infarct size)/ AAR) did not change significantly between ‘day 2’ and ‘1 week’ (%MSI (SD), 27.6 (23) vs. 28.9 (23.8), p=0.85).
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