Functional Recovery After Acute Myocardial Infarction: Comparison Between Angiography, Electrocardiography, and Cardiovascular Magnetic Resonance Measures of Microvascular Injury

Abstract

We examined the relation between angiographic, electrocardiographic, and gadolinium-enhanced cardiovascular magnetic resonance (CMR) characteristics of microvascular obstruction (MVO), and their predictive value on functional recovery after acute myocardial infarction (AMI). Microvascular obstruction on CMR has been shown to predict left ventricular (LV) remodeling, but it is not well known how it compares with commonly used criteria of microvascular injury, and earlier reports have produced conflicting results on the significance and extent of MVO. Thrombolysis In Myocardial Infarction (TIMI) flow grade, myocardial blush grade (MBG), and ST-segment resolution were assessed in 60 patients with AMI treated with primary stenting. Cardiovascular magnetic resonance was performed between 2 and 9 days after revascularization to determine early MVO on first-pass perfusion imaging, late MVO on late gadolinium-enhanced imaging, and infarct size and transmural extent. Cine imaging was used to determine LV volumes and global and regional function at baseline and 4-month follow-up. Early and late MVO were both related to incomplete ST-segment resolution (p = 0.002 and p = 0.01, respectively), but not to TIMI flow grade and MBG. Of all angiographic, electrocardiographic, and CMR variables, late MVO was the strongest parameter to predict changes in end-diastolic volume (beta = 0.53; p = 0.001), end-systolic volume (beta = 8.67; p = 0.001), and ejection fraction (beta = 3.94; p = 0.006) at follow-up. Regional analysis showed that late MVO had incremental diagnostic value to transmural extent of infarction (odds ratio: 0.18; p < 0.0001). In patients after revascularized AMI, late MVO proved a more powerful predictor of global and regional functional recovery than all of the other characteristics, including transmural extent of infarction.