Background— The current understanding of the pathophysiology of coronary artery disease is based largely on postmortem studies. Optical coherence tomography (OCT) is a high-resolution (≈10 μm), catheter-based imaging modality capable of investigating detailed coronary plaque morphology in vivo. Methods and Results— Patients undergoing cardiac catheterization were enrolled and categorized according to their clinical presentation: recent acute myocardial infarction (AMI), acute coronary syndromes (ACS) constituting non-ST-segment elevation AMI and unstable angina, or stable angina pectoris (SAP). OCT imaging was performed with a 3.2F catheter. Two observers independently analyzed the images using the previously validated criteria for plaque characterization. Of 69 patients enrolled, 57 patients (20 with AMI, 20 with ACS, and 17 with SAP) had analyzable images. In the AMI, ACS, and SAP groups, lipid-rich plaque (defined by lipid occupying ≥2 quadrants of the cross-sectional area) was observed in 90%, 75%, and 59%, respectively ( P =0.09). The median value of the minimum thickness of the fibrous cap was 47.0, 53.8, and 102.6 μm, respectively ( P =0.034). The frequency of thin-cap fibroatheroma (defined by lipid-rich plaque with cap thickness ≤65 μm) was 72% in the AMI group, 50% in the ACS group, and 20% in the SAP group ( P =0.012). No procedure-related complications occurred. Conclusions— OCT is a safe and effective modality for characterizing coronary atherosclerotic plaques in vivo. Thin-cap fibroatheroma was more frequently observed in patients with AMI or ACS than SAP. This is the first study to compare detailed in vivo plaque morphology in patients with different clinical presentations.

Background—: Optical coherence tomography (OCT) was recently introduced to optimize percutaneous coronary intervention. However, the exact incidence and significance of poststent OCT findings are unknown. Methods and Results—: A total of 900 lesions treated with 1001 stents in 786 patients who had postprocedure OCT imaging were analyzed to evaluate the incidence of poststent OCT findings and to identify the OCT predictors for device-oriented clinical end points, including cardiac death, target vessel–related myocardial infarction, target lesion revascularization, and stent thrombosis. Patients were followed up to 1 year. Stent edge dissection was detected in 28.7% of lesions, and incomplete stent apposition was detected in 39.1% of lesions. The incidences of smooth protrusion, disrupted fibrous tissue protrusion, and irregular protrusion were 92.9%, 61.0%, and 53.8%, respectively. Small minimal stent area, defined as a lesion with minimal stent area <5.0 mm ² in a drug-eluting stent or <5.6 mm ² in a bare metal stent, was observed in 40.4% of lesions. One-year device-oriented clinical end points occurred in 33 patients (4.5%). Following adjustment, irregular protrusion and small minimal stent area were independent OCT predictors of 1-year device-oriented clinical end points ( P =0.003 and P =0.012, respectively). Conclusions—: Abnormal poststent OCT findings were frequent. Irregular protrusion and small minimal stent area were independent predictors of 1-year device-oriented clinical end points, which were primarily driven by target lesion revascularization.

Plaque erosion, compared with plaque rupture, has distinctly different underlying pathology and therefore may merit tailored therapy. In this study, we aimed to assess whether patients with acute coronary syndrome (ACS) caused by plaque erosion might be stabilized by anti-thrombotic therapy without stent implantation. This was a single-centre, uncontrolled, prospective, proof-of concept study. Patients with ACS including ST-segment elevation myocardial infarction were prospectively enrolled. If needed, aspiration thrombectomy was performed. Patients diagnosed with plaque erosion by optical coherence tomography (OCT) and residual diameter stenosis 50% reduction of thrombus volume at 1 month compared with baseline. The secondary endpoint was a composite of cardiac death, recurrent ischaemia requiring revascularization, stroke, and major bleeding. Among 405 ACS patients with analysable OCT images, plaque erosion was identified in 103 (25.4%) patients. Sixty patients enrolled and 55 patients completed the 1-month follow-up. Forty-seven patients (47/60, 78.3%; 95% confidence interval: 65.8–87.9%) met the primary endpoint, and 22 patients had no visible thrombus at 1 month. Thrombus volume decreased from 3.7 (1.3, 10.9) mm³ to 0.2 (0.0, 2.0) mm³. Minimal flow area increased from 1.7 (1.4, 2.4) mm² to 2.1 (1.5, 3.8) mm². One patient died of gastrointestinal bleeding, and another patient required repeat percutaneous coronary intervention. The rest of the patients remained asymptomatic. For patients with ACS caused by plaque erosion, conservative treatment with anti-thrombotic therapy without stenting may be an option.