Coronary Culprit Lesion Location and Intramyocardial Hemorrhage in STEMI

BACKGROUND: Intramyocardial hemorrhage (IMH) is a major determinant of adverse outcome in patients with ST-segment–elevation myocardial infarction, therefore making it a promising therapeutic target. This study aimed to investigate the association between coronary culprit lesion location and IMH in acute ST-segment–elevation myocardial infarction. METHODS: We analyzed 767 patients with ST-segment–elevation myocardial infarction undergoing cardiac magnetic resonance imaging, including T2* mapping at 4 (interquartile range, 3–5) days after infarction. Coronary culprit vessel and lesion, Thrombolysis in Myocardial Infarction flow, and collateral circulation were assessed. The primary end point was the presence of IMH on cardiac magnetic resonance. An exploratory clinical end point at 12 months was defined as major adverse cardiac events, which comprised all-cause mortality, reinfarction, and new congestive heart failure. RESULTS: Median age was 59 (interquartile range, 53–67) years, and 19% (n=144) were female. IMH was detected in 265 (35%) patients. IMH was present in 27% (n=76/286) of patients with right coronary artery, in 39% (n=136/351) with left anterior descending artery, and 44% (n=48/109) with circumflex artery (CX) as the culprit lesion ( P <0.001). Segment 11 (CX proximal) showed the highest (n=23/41, 56%), segment 1 (right coronary artery proximal) the lowest risk for IMH (n=22/85, 26%). CX infarction remained independently associated with IMH (odds ratio, 1.27 [95% CI, 1.07–1.50]; P =0.005) after adjustment for angiographic and clinical IMH determinants, including Thrombolysis in Myocardial Infarction flow, ischemic time, and troponin T concentration. Collateral flow was least frequent in CX infarctions (n=15/109, 14%) compared with right coronary artery (n=117/286, 41%) and left anterior descending infarctions (n=101/351, 29%; P <0.001). Patients with CX infarction showed the highest rate of major adverse cardiac events (7%) compared with left anterior descending (6%) and right coronary artery (2%) infarctions ( P =0.039). CONCLUSIONS: CX infarctions were independently associated with the highest risk of IMH. The low prevalence of collateral circulation may contribute to this susceptibility. These findings define CX infarctions as a high-risk phenotype that may benefit from targeted cardioprotective strategies.