Optical coherence tomography (OCT) evaluation of intermediate coronary lesions in patients with NSTEMI

Introduction: Coronary angiography is commonly performed following non-ST segment elevation myocardial infarction (NSTEMI) to assess the need for revascularization. Some of these patients have myocardial infarction (MI) with no obstructive coronary atherosclerosis (MINOCA). Patients without severe obstructive lesions are usually treated conservatively. However, coronary angiography has known limitations in the assessment of lesion severity. We report our experience of using coronary Optical Coherence Tomography (OCT) in a series of patients without severe obstructive coronary lesions. Methods: 165 patients underwent coronary OCT at Vancouver General Hospital. NSTEMI was the clinical presentation in 70 patients and 26 had angiographically intermediate lesions with 40%–69% diameter stenosis. Prior to OCT image acquisition, intracoronary nitroglycerin 100–200 μg was administered. Blood in the vessel was displaced using contrast media by manual injections. Results: OCT of the angiographically intermediate lesions showed larger minimal luminal area (MLA) than the angiographically severe lesions (MLA 3.3 mm² ± 1.8 mm² vs. 1.6 mm² ± 0.6 mm², p < 0.001) and less severe % lumen area stenosis (54.2% ± 11.4% vs. 70.9% ± 6.8%, p = 0.001). Plaque rupture or intracoronary thrombus was detected in 8/26 (31%) patients. PCI with stent deployment was performed in 16 patients (62%). Conclusion: In stabilized patients with NSTEMI and angiographically intermediate disease, OCT examination confirmed the lack of severe anatomical stenosis in most patients. However, OCT also identified coronary lesions with unstable features. Further research is needed to help guide management of this subgroup of patients.