Friday Posters 321. THE PREVALENCE OF MYOCARDIAL SCAR IN PATIENTS NO PRIOR HISTORY OF CARDIAC DISEASE DETECTED BY DELAYED-ENHANCEMENT CARDIAC MAGNETIC RESONANCE

Background: Patients with myocardial scar (scar) are at increased risk for cardiovascularmortality andmorbidity. Delayed enhancement cardiac magnetic resonance imaging (DE-CMR) is highly accurate in the detection of scar. The pattern ofmyocardial scar can be divided into 2 groups: 1. Coronary artery disease (CAD) based on location, ie extending from subendocardium to subepicardium; and 2. Non-CAD based on mid-myocardial or epicardial location. The prevelance of these patterns of scar in patients with no prior history of infarction or CAD is unknown. Purpose: To assess the prevalence of scar (both CAD and Non-CAD) by DE-CMR in patients with clinically suspected CAD and no previous cardiac disease. Methods: We prospectively enrolled 42 consecutive patients (pts) without a prior history of cardiac disease including myocardial infarction who were referred for elective coronary angiography (CA) based on clinical suspicion of CAD. DE-CMR was performed in all patients within 24 hrs of CA. DE-CMR images were scored visually, blinded to patient identity, using a 17-segment model. The presence of silent MI by DE-CMR was defined as the presence of hyperenhanced myocardium in a pattern typical of CAD. Non-CAD pattern of hyperenhancement was defined as either midmyocardial or epicardial HE representing primary myocardial disease. Patients were considered positive for CAD if there was ≥70% coronary stenosis on CA. Results: The prevalence of CAD by CA was 38% (16 pts). DE-CMR showed evidence of HE in 9 pts (21%). Four (44%) patients had a HE pattern consistent with CAD, and 5 pts. (56%) had Non-CAD type of HE. The mean silent MI size was 9.4% of total LV mass, the mean size of scar in the Non-CAD group was 1% of total LV mass. Of the 4 pts. with evidence of silent MI by DE-CMR, three had significant stenosis on CA, and one pt. had non-obstructive disease on CA. Among the 5 pts. with evidence of Non-CAD type of scar, 4 had no CAD onCA, one pt. with HE in the midmyocardial basal septum (0.8% of LV mass) had evidence of obstructive CAD (posterior descending artery) on CA. Conclusion: There is a high prevalence of scar in patients with clinically suspected CAD but without previously known cardiac disease. DE-CMR has additive diagnostic value for the evaluation of patients with clinical suspicion of CAD.