Residual ischemia location after STEMI by CMR and association with non-culprit coronary artery disease

Abstract Background Many ST-segment elevation myocardial infarction (STEMI) patients present with non-culprit coronary artery disease. In cases with incomplete revascularization, stress cardiac magnetic resonance (sCMR) could help detect and locate residual ischemia. Purpose We aim to evaluate the usefulness of sCMR to detect and locate residual ischemia in STEMI patients after discharge and correlate the findings with angiographical non-culprit coronary lesions, if any. Methods Reperfused, stable STEMI patients submitted to undergo sCMR within the first year after STEMI were included in the cohort. Index coronary angiography was revised, culprit and non-culprit coronary artery disease were registered, and significant stenoses were defined as ≥50% by visual assessment. Residual ischemia on sCMR (by first-pass vasodilator stress perfusion) was analysed and categorized as either absent or present in anterior, lateral, and inferior territories. Unrevascularized non-culprit coronary lesions were correlated with territories with residual ischemia on sCMR and lesions in subsequent coronary angiography. A p-value <0.05 was considered statistically significant. Results The study group was made up of 234 patients who underwent sCMR within the first year after STEMI (mean age 58.95±11.85 years, 78.2% male, 48.7% anterior infarction). Residual ischemia by sCMR was noted in 63 (26.9%) patients. In the 95 patients (40.6%) who underwent complete revascularization during index admission, residual ischemia by sCMR was seldom detected (n=14, 14.7%) and distributed on anterior (n=8), lateral (n=3) and inferior (n=4) territories. More than half of the cohort (n=139, 59.4%) depicted unrevascularized non-culprit coronary lesions, and residual ischemia was detected in 49 (35.3%) patients. Non-culprit lesions on left anterior descendent artery (n=62) associated with ischemia in 38.7% of cases (n=24), most commonly in the anterior territory (n=17, 70.8%). Similar findings were noted for lesions on circumflex artery (n=66), which depicted residual ischemia in 34.8% (n=23) of cases and most frequently in the lateral territory (n=13, 56.5%); and lesions in right coronary artery (n=45), which depicted residual ischemia in 42.2% (n=19) of cases, most commonly in the inferior territory (n=13, 68.4%). Significant coronary stenosis was found in most patients who underwent subsequent coronary angiography after residual ischemia detection (41 out of 47, 87.2%). Conclusions One third of STEMI patients with incomplete revascularization and non-culprit coronary artery disease depict residual ischemia on sCMR, the location of which generally correlates with index coronary anatomy and significant stenosis in subsequent coronary angiography. Residual ischemia is infrequent in patients with complete revascularization, but not inexistent. sCMR should be considered in selected STEMI patients according to coronary anatomy and/or symptoms to guide therapy.Stress CMR and ischemia location