Abstract 1750: Collateral Flow and Early Reperfusion Reduce Infarct Transmurality and Prevent Left Ventricular Remodeling After ST-Segment Elevation Acute Myocardial Infarction
The presence of left ventricular (LV) remodeling following an acute ST-segment elevation myocardial infarction (STEMI) is associated with adverse outcomes. We hypothesized that early reperfusion and collateral flow prevent infarct transmural progression and adverse remodeling after STEMI.
Methods: Contrast-enhanced cardiac magnetic resonance was performed in 89 subjects treated with primary angioplasty of an occluded artery (TIMI ≤ 1) at a mean of 3 ± 2 days post STEMI and repeated in 65 subjects at 5 ± 3 months. Regional wall motion (WM) and infarct transmurality were scored on a 5 point scale using a 17 segment model. LV end diastolic volume index (EDVI), end systolic volume index (ESVI), and ejection fraction (EF) were measured.
Results: Subjects were divided in 2 groups: Group 1 had 61 subjects with either good collateral flow (Rentrop’s grade ≥ 2) or early reperfusion (≤ 3 hours); and Group 2 had 28 subjects with both poor collateral flow (Rentrop’s grade ≤ 1) and late reperfusion (> 3 hours). Group 1 had– on the initial and follow-up scans–significantly better WM score, smaller LV volumes, and higher EF when compared to Group 2 (Table⇓). These changes reflected the differences in the initial number of segment with transmural infarct (1.59 ± 2.0 in Group 1 vs. 3.46 ± 2.0 in Group 2, p < 0.001). Additionally, in subjects with poor collateral flow, early reperfusion decreased the number of transmural infarcts (p = 0.018). Likewise, the presence of good collateral flow also significantly reduced the number of transmural infarcts in patients with early reperfusion (p = 0.05) and late reperfusion (p = 0.001).
Conclusion: The presence of angiographic collateral flow and early reperfusion are major determinants of infarct transmurality. By salvaging a rim of epicardial myocardium, early reperfusion and collateral flow improve global and regional wall motion and attenuate LV dilation. The role of collateral flow is especially relevant in patients with late reperfusion.