Abstract 19100: Transmural and Lateral Remodeling of the Post-infarction Scar Tissue: Serial Cardiac Magnetic Resonance Imaging Study From the Metocard-Cnic Trial

Abstract

Background: The remodeling process that occurs following an acute myocardial infarction produces changes in the myocardial scar and the surrounding tissue. The spatial evolution of the scar has not been yet characterized using MRI. Purpose: To describe the spatial behavior of myocardial scar on its transmural and lateral dimensions following an acute myocardial infarction. Methods: A total of 220 patients with acutely reperfused anterior STEMI (METOCARD-CNIC trial population) were studied. All the patients underwent cardiac MRI at day 7 and 6 months after presentation. The spatial distribution of the scar was analyzed using short axis late gadolinium enhancement images. Endo and epicardial contours of each LV short axis slice was traced, and each one was divided by 100 cords for analysis (Figure 1A). The lateral extension was defined as the percentage of cords with enhancement in every slice, and the transmural extension as the percentage of enhancement within each cord, nested in the lateral extension (Figure 1B). All slices were weighed according to their relative mass. Data were compared by paired t test. Results: Six months after STEMI, myocardial scar was smaller in both dimensions (Figure 1C). Mean ± SEM lateral scar, as a percentage of cords affected, at 7 days and 6 months were, respectively, 27.9 ± 1.1 and 22.2 ± 1.0 (p < 0.001). Transmurality also decreased significantly, mean percentage at day 7 was 46.8 ± 1.5 and at 6 months 35.4 ± 1.4 (p < 0.001). All these changes were accompanied by an increase in LV end-diastolic volume (171.47 ± 2.5 and 190.61 ± 2.9 (p < 0.001)). Conclusions: The myocardial scar remodeling process following a STEMI includes a reduction in both its transmural and lateral extensions.