Abstract 202: Myocardium at Risk in STEMI: Validation of T2 Edema Imaging Using Magnetic Resonance Against the Angiographic APPROACH-score
Background: The assessment of the area at risk with T2-weighted imaging using MRI is a relatively new method, which could be an interesting alternative in clinical studies in STEMI patients to analyse the effects of different therapies in revascularization. Purpose of this trial was to assess the area at risk and myocardial salvage by MRI and to compare it to the validated angiographic APPROACH-Score in a large consecutive patient cohort.
Methods: From November 2006 to February 2008 189 patients undergoing primary PCI in acute STEMI were enrolled. Myocardial salvage was assessed by MRI 2– 4 days after primary PCI with measurement of the extension of myocardial edema in T2-weighted images and of infarct size with delayed enhancement imaging, both sequences covering the whole left ventricle. Angiographic scoring was done by use of the former validated APPROACH-Score. MRI measurements and angiographic scoring were done by blinded investigators.
Results: All images were assessable for measurements of the area at risk, infarct size and consecutively the myocardial salvage. The area at risk in the MRI-Studies showed a good correlation with the angiographic area at risk measured with the APPROACH-Score (r=0.858; p<0.001). However, as shown by Bland-Altman-analyses there was a certain bias towards an overestimation of the area at risk by MRI in comparison to angiographic scoring (36.5 %LV vs. 27.8 %LV, p<0.001). The infarct size measured by MRI was 18,2±11,6 %LV. The calculated myocardial salvage was 18,3±11,8 %LV. The time from symptom-onset to reperfusion had a significant impact on the myocardial salvage.
Conclusions: The measurement of the area at risk by MRI shows excellent correlation to the angiographic APPROACH-Score with slight overestimation. This might be explained by the former validation of the angiographic score by pathological studies mostly in human hearts without recent myocardial infarction, whereas acute edema represents also some kind of swelling at an early stage. Assessment of the myocardial salvage by MRI is therefore a promising tool for the assessment of myocardial salvage.