Culprit Lesion in Patients With ST-elevation Myocardial Infarction is Severely Narrowed With Large Plaque Burden: A Combined Intravascular Ultrasound and Optical Coherence Tomography Study

Background: There have been controversies on the degree of stenosis of the culprit lesion in patients with ST-elevation myocardial infarction (STEMI). In the past it was thought the culprit lesion for STEMI had only mild to moderate stenosis. However, recent studies suggested that in fact the degree of the luminal narrowing might be severe at the culprit site. Aim: The aim of the current study was to investigate the severity and the detailed morphologic characteristics of the culprit lesion in patients with STEMI using intravascular ultrasound (IVUS) and optical coherence tomography (OCT). Methods and Results: A total of 111 STEMI patients (67.8±11.2 years, 89 male) who underwent percutaneous coronary intervention within 12 hours from symptom onset were included. TIMI flow grade 2 or 3 was achieved in 108 (97%) patients after thrombectomy. Both OCT and IVUS were performed. Minimum lumen cross-sectional area (MLA) and plaque burden (PB) were 3.14±1.45 mm 2 and 83.0±7.24% by IVUS. Patients were divided into 2 groups on the basis of MLA by IVUS: Group A (MLA <4 mm 2 , n=104) and Group B (MLA >4 mm 2 , n=7). Group A had a higher incidence of PB >70% compared to Group B (99.0% vs 28.6%, p<0.001). OCT revealed that lipid plaque, microchannel and macrophage were more frequent in Group A than in Group B. The incidence of plaque rupture tended to be higher in Group A than in Group B (Figure). Conclusions: Among STEMI patients, more than 90% of culprit lesions have a small MLA (<4.0 mm 2 ) with large plaque burden. Severely narrowed culprit lesion had more features of vulnerability.