Study, however, misses safety endpoint Optical coherence tomography (OCT) guidance reduced the rate of stent implantation by 15% in primary percutaneous coronary intervention (PCI) compared to angiographic guidance in the EROSION III study. The Chinese study’s findings were presented Thursday at Transcatheter Cardiovascular Therapeutics (TCT) 2021 in Orlando, Florida, by investigator Bo Yu, MD, PhD, from the 2nd Affiliated Hospital of Harbin Medical University, China. The results show that OCT can be considered for optimized reperfusion strategy decision-making for ST-segment elevation myocardial infarction (STEMI) patients, he said. Nevertheless, the study did not meet its primary safety endpoint: incidence of composite events, including cardiac death, recurrent myocardial infarction, target lesion revascularization (TLR) and unstable angina-induced rehospitalization, within 1 month. Intracoronary stenting remains common practice irrespective of underlying pathology. Although the incidence is low, stent implantation during PCI is associated with both early and late complications such as stent thrombosis, restenosis and neoatherosclerosis. The earlier EROSION I study suggests that a non-stenting strategy could be an option for the treatment of STEMI caused by non-obstructive erosions (stenosis diameter <70%), said Yu, stressing, however, that “Evidence is limited.” Furthermore, “OCT allows to accurately evaluate the mechanisms of STEMI, which provides a potential possibility for individualized precision treatment,” Yu said during his presentation, potentially leading to “a safer treatment strategy in STEMI without obstructive lesion”. EROSION III was, therefore, set up to compare the reperfusion strategy and clinical outcomes of 226 STEMI patients treated by either standard angiography-guided (114 subjects) PCI procedures, or OCT-guided (112 subjects) PCI. A conservative non-stenting strategy was recommended in the OCT group for those with culprit plaque erosions, certain ruptures without dissection and hematoma, and spontaneous coronary artery dissection (SCAD) without obstructive stenosis. Meanwhile, for the angiography group, the reperfusion strategy was decided by the operators according to local practice. The prospective, randomized controlled study ran in multiple sites across China. In the OCT group, 26% of patients had plaque erosion, while 41% had plaque rupture treated medically. Uncommon STEMI causes included calcified nodule, intimal fissures, spasm and non-atherosclerotic causes, which were “treated mainly medically,” said Yu. Stenting during primary PCI – the primary endpoint – occurred in 43.8% of the OCT-guided group versus 58.8% of those with angiography-guided procedures, a significant 15% reduction (P=0.024). Patients not treated by stent had “very mild stenosis,” Yu noted. The study missed its primary composite events safety endpoint, however, with a log-rank p=0.67 for OCT versus angiography guidance. Nevertheless, “OCT guidance during primary PCI was feasible and safe without increasing MACE at 1-month follow-up,” according to Yu’s presentation. Two (3.2%) of the 63 patients receiving OCT-guided procedures without stenting suffered cardiac death, as did one of the 49 patients (2%) in the OCT-guided stenting group, three of the 47 patients (6.4%) in the angio-guided non-stenting cohort and one of the 67 (1.5%) in the angio-guided stenting group (log-rank P value = 0.478). No patient had recurrent myocardial infarction; however, target lesion revascularization occurred in five (7.9%) of the OCT-guided non-stenting patients and four (8.5%) of the angio-guided non-stenting patients. None of the stented patients had target lesion revascularization (overall log-rank P value = 0.012). Unstable angina-induced rehospitalization happened for three patients (4.8%) in the OCT-guided group without stenting, one (2.1%) in the angio-guided non-stenting cohort and one (1.5%) of the angio-guided stenting patients (log-rank P value = 0.379). Still, Yu stressed that the 15% reduction in stenting associated with OCT means it can be considered for decision-making, “customizing and optimizing the reperfusion strategy for STEMI patients.”