Computed Tomography Angiography Characteristics of Thin-Cap Fibroatheroma in Patients With Diabetes.

BACKGROUND: It was recently reported that thin-cap fibroatheroma (TCFA) detected by optical coherence tomography was an independent predictor of future cardiac events in patients with diabetes. However, the clinical usefulness of this finding is limited by the invasive nature of optical coherence tomography. Computed tomography angiography (CTA) characteristics of TCFA have not been systematically studied. The aim of this study was to investigate CTA characteristics of TCFA in patients with diabetes. METHODS AND RESULTS: Patients with diabetes who underwent preintervention CTA and optical coherence tomography were included. Qualitative and quantitative analyses were performed for plaques on CTA. TCFA was assessed by optical coherence tomography. Among 366 plaques in 145 patients with diabetes, 111 plaques had TCFA. The prevalence of positive remodeling (74.8% versus 50.6%, P<0.001), low attenuation plaque (63.1% versus 33.7%, P<0.001), napkin-ring sign (32.4% versus 11.0%, P<0.001), and spotty calcification (55.0% versus 34.9%, P<0.001) was significantly higher in TCFA than in non-TCFA. Low-density noncalcified plaque volume (25.4 versus 15.7 mm3, P<0.001) and remodeling index (1.30 versus 1.20, P=0.002) were higher in TCFA than in non-TCFA. The presence of napkin-ring sign, spotty calcification, high low-density noncalcified plaque volume, and high remodeling index were independent predictors of TCFA. When all 4 predictors were present, the probability of TCFA increased to 82.4%. CONCLUSIONS: The combined qualitative and quantitative plaque analysis of CTA may be helpful in identifying TCFA in patients with diabetes. REGISTRATION INFORMATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04523194.

Exploring Possible Links: Thigh Muscle Mass, Apolipoproteins, and Glucose Metabolism in Peripheral Artery Disease-Insights from a Pilot Sub-Study following Endovascular Treatment.

Peripheral artery disease (PAD) compromises walking and physical activity, which results in further loss of skeletal muscle. The cross-sectional area of the thigh muscle has been shown to be correlated with systemic skeletal muscle volume. In our previous pilot study, we observed an increase in thigh muscle mass following endovascular treatment (EVT) in patients with proximal vascular lesions affecting the aortoiliac and femoropopliteal arteries. Considering the potential interactions between skeletal muscle, lipid profile, and glucose metabolism, we aimed to investigate the relationship between thigh muscle mass and apolipoproteins as well as glucose metabolism in PAD patients undergoing EVT. This study is a prespecified sub-study conducted as part of a pilot study. We prospectively enrolled 22 symptomatic patients with peripheral artery disease (PAD) and above-the-knee lesions, specifically involving the blood vessels supplying the thigh muscle. The mid-thigh muscle area was measured with computed tomography before and 6 months after undergoing EVT. Concurrently, we measured levels of apolipoproteins A1 (Apo A1) and B (Apo B), fasting blood glucose, 2 h post-load blood glucose (using a 75 g oral glucose tolerance test), and glycated hemoglobin A1c (HbA1c). Changes in thigh muscle area (delta muscle area: 2.5 ± 8.1 cm2) did not show significant correlations with changes in Apo A1, Apo B, fasting glucose, 2 h post-oral glucose tolerance test blood glucose, HbA1c, or Rutherford classification. However, among patients who experienced an increase in thigh muscle area following EVT (delta muscle area: 8.41 ± 5.93 cm2), there was a significant increase in Apo A1 (pre: 121.8 ± 15.1 mg/dL, 6 months: 136.5 ± 19.5 mg/dL, p < 0.001), while Apo B remained unchanged (pre: 76.4 ± 19.2 mg/dL, 6 months: 80.5 ± 4.9 mg/dL). Additionally, post-oral glucose tolerance test 2 h blood glucose levels showed a decrease (pre: 189.7 ± 67.5 mg/dL, 6 months: 170.6 ± 69.7 mg/dL, p = 0.075). Patients who exhibited an increase in thigh muscle area demonstrated more favorable metabolic changes compared to those with a decrease in thigh muscle area (delta muscle area: -4.67 ± 2.41 cm2). This pilot sub-study provides insights into the effects of EVT on thigh muscle, apolipoproteins, and glucose metabolism in patients with PAD and above-the-knee lesions. Further studies are warranted to validate these findings and establish their clinical significance. The trial was registered on the University Hospital Medical Information Network Clinical Trials Registry (UMIN000047534).

Clinical Background and Coronary Artery Lesions Characteristics in Japanese Patients With Acute Coronary Syndrome Suffering Major Bleeding.

Background: Although the clinical factors that predict major bleeding in Western patients with acute coronary syndrome (ACS) are becoming elucidated, they have not been fully investigated, especially coronary lesion characteristics, in a Japanese population. Methods and Results: ACS patients (n=1,840) were divided into a "bleeding group" and a "no-bleeding group," according to whether they had major bleeding during the 2-year follow-up period, to investigate the prognostic effect of bleeding and the predictive factors of bleeding. Among them, patients who underwent primary percutaneous coronary intervention with optical coherence tomography (OCT) guidance (n=958) were examined to identify the effect of coronary lesion characteristics on bleeding. Of the 1,840 enrolled patients, 124 (6.7%) experienced major bleeding during the 2-year follow-up period. Incidence of cardiovascular death during the 2-year follow-up period was significantly higher among patients with major bleeding (26.4% vs. 8.5%, P=0.001). OCT examination showed that disrupted fibrous cap (DFC: 68% vs. 48%, P=0.014) and calcified plaque (63% vs. 42%, P=0.011) were more prevalent in the bleeding group. DFC was a predictor of major bleeding in the multivariate Cox proportional hazards analyses (hazard ratio 2.135 [95% confidence interval 1.070-4.263], P<0.001). Conclusions: ACS patients with major bleeding had poorer cardiac outcomes. Advanced atherosclerosis at the culprit lesion influences the higher incidence of major bleeding in ACS patients.

Higher Noncalcified Plaque Volume Is Associated With Increased Plaque Vulnerability and Vascular Inflammation.

BACKGROUND: Recently, it was reported that noncalcified plaque (NCP) volume was an independent predictor for cardiac events. Pericoronary adipose tissue (PCAT) attenuation is a marker of vascular inflammation and has been associated with increased cardiac mortality. The aim of this study was to evaluate the relationships between NCP volume, plaque vulnerability, and PCAT attenuation. METHODS: Patients who underwent preintervention coronary computed tomography angiography and optical coherence tomography were enrolled. Plaque volume was measured by computed tomography angiography, plaque vulnerability by optical coherence tomography, and the level of coronary inflammation by PCAT attenuation. The plaques were divided into 2 groups of high or low NCP volume based on the median NCP volume. RESULTS: Among 704 plaques in 454 patients, the group with high NCP volume had a higher prevalence of lipid-rich plaque (87.2% versus 75.9%; P<0.001), thin-cap fibroatheroma (38.1% versus 20.7%; P<0.001), macrophage (77.8% versus 63.4%; P<0.001), microvessel (58.2% versus 42.9%; P<0.001), and cholesterol crystal (42.0% versus 26.7%; P<0.001) than the group with low NCP plaque volume. The group with high NCP volume also had higher PCAT attenuation than the group with low NCP volume (-69.6±10.0 versus -73.5±10.6 Hounsfield unit; P<0.001). In multivariable analysis, NCP volume was significantly associated with thin-cap fibroatheroma and high PCAT attenuation. In the analysis of the combination of PCAT attenuation and NCP volume, the prevalence of thin-cap fibroatheroma was the highest in the high PCAT attenuation and high NCP volume group and the lowest in the low PCAT attenuation and low NCP volume group. CONCLUSIONS: Higher NCP volume was associated with higher plaque vulnerability and vascular inflammation. The combination of PCAT attenuation and NCP volume may help identify plaque vulnerability noninvasively. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04523194.

Coronary Plaque Characteristics and Underlying Mechanism of Acute Coronary Syndromes in Different Age Groups of Patients With Diabetes.

BACKGROUND: High cardiovascular mortality has been reported in young patients with diabetes. However, the underlying pathology in different age groups of patients with diabetes has not been studied. METHODS AND RESULTS: The aim of this study was to investigate the plaque characteristics and underlying pathology of acute coronary syndrome in different age groups of patients with or without diabetes in a large cohort. Patients who presented with acute coronary syndrome and underwent preintervention optical coherence tomography imaging were included. Culprit plaque was classified as plaque rupture, plaque erosion, or calcified plaque and stratified into 5 age groups. Plaque characteristics including features of vulnerability were examined by optical coherence tomography. Among 1394 patients, 482 (34.6%) had diabetes. Patients with diabetes, compared with patients without diabetes, had a higher prevalence of lipid-rich plaque (71.2% versus 64.8%, P=0.016), macrophage (72.0% versus 62.6%, P<0.001), and cholesterol crystal (27.6% versus 19.7%, P<0.001). Both diabetes and nondiabetes groups showed a decreasing trend in plaque erosion with age (patients with diabetes, P=0.020; patients without diabetes, P<0.001). Patients without diabetes showed an increasing trend with age in plaque rupture (P=0.004) and lipid-rich plaque (P=0.018), whereas patients with diabetes had a high prevalence of these vulnerable features at an early age that remained high across age groups. CONCLUSIONS: Patients without diabetes showed an increasing trend with age in plaque rupture and lipid-rich plaque, whereas patients with diabetes had a high prevalence of these vulnerable features at an early age. These results suggest that atherosclerotic vascular changes with increased vulnerability start at a younger age in patients with diabetes. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifiers: NCT04523194, NCT03479723. URL: https://www.umin.ac.jp/ctr/. Unique identifier: UMIN000041692.

Diagnosis and Prognostic Value of the Underlying Cause of Acute Coronary Syndrome in Optical Coherence Tomography-Guided Emergency Percutaneous Coronary Intervention.

Background The prognostic impact of optical coherence tomography-diagnosed culprit lesion morphology in acute coronary syndrome (ACS) has not been systematically examined in real-world settings. Methods and Results This investigator-initiated, prospective, multicenter, observational study was conducted at 22 Japanese hospitals to identify the prevalence of underlying ACS causes (plaque rupture [PR], plaque erosion [PE], and calcified nodules [CN]) and their impact on clinical outcomes. Patients with ACS diagnosed within 24 hours of symptom onset undergoing emergency percutaneous coronary intervention were enrolled. Optical coherence tomography-guided percutaneous coronary intervention recipients were assessed for underlying ACS causes and followed up for major adverse cardiac events (cardiovascular death, myocardial infarction, heart failure, or ischemia-driven revascularization) at 1 year. Of 1702 patients with ACS, 702 (40.7%) underwent optical coherence tomography-guided percutaneous coronary intervention for analysis. PR, PE, and CN prevalence was 59.1%, 25.6%, and 4.0%, respectively. One-year major adverse cardiac events occurred most frequently in patients with CN (32.1%), followed by PR (12.4%) and PE (6.2%) (log-rank P<0.0001), primarily driven by increased cardiovascular death (CN, 25.0%; PR, 0.7%; PE, 1.1%; log-rank P<0.0001) and heart failure trend (CN, 7.1%; PR, 6.8%; PE, 2.2%; log-rank P<0.075). On multivariate Cox regression analysis, the underlying ACS cause was associated with 1-year major adverse cardiac events (CN [hazard ratio (HR), 4.49 [95% CI, 1.35-14.89], P=0.014]; PR (HR, 2.18 [95% CI, 1.05-4.53], P=0.036]; PE as reference). Conclusions Despite being the least common, CN was a clinically significant underlying ACS cause, associated with the highest future major adverse cardiac events risk, followed by PR and PE. Future studies should evaluate the possibility of ACS underlying cause-based optical coherence tomography-guided optimization.

Optical Coherence Tomography-Guided Percutaneous Coronary Intervention for ST-Segment Elevation Myocardial Infarction: Rationale and Design of the ATLAS-OCT Study.

Even after successful revascularization with primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI), subsequent adverse events still occur. Previous studies have suggested potential benefits of intravascular imaging, including optical coherence tomography (OCT). However, the feasibility of OCT-guided primary PCI has not been systematically examined in these patients. The ATLAS-OCT (ST-elevation Acute myocardial infarcTion and cLinicAl outcomeS treated by Optical Coherence Tomography-guided percutaneous coronary intervention) trial was designed to investigate the feasibility of OCT guidance during primary PCI for STEMI in experienced centers with expertise on OCT-guided PCI as a prospective, multicenter registry of consecutive patients with STEMI who underwent a primary PCI. The sites' inclusion criteria are as follows: (1) acute care hospitals providing 24/7 emergency care for STEMI, and (2) institutions where OCT-guided PCI is the first choice for primary PCI in STEMI. All patients with STEMI who underwent primary PCI at participating sites will be consecutively enrolled, irrespective of OCT use during PCI. The primary end point will be the rate of successful OCT imaging during the primary PCI. As an ancillary imaging modality to angiography, OCT provides morphologic information during PCI for the assessment of plaque phenotypes, vessel sizing, and PCI optimization. Major adverse cardiac events, defined as a composite of all-cause death, myocardial infarction, and target vessel revascularization at 1 year, will also be recorded. The ATLAS-OCT study will clarify the feasibility of OCT-guided primary PCI for patients with STEMI and further identify a suitable patient group for OCT-guided primary PCI.

Early recurrence of attack after myocardial infarction with non-obstructive coronary arteries: a case report.

Background: Diagnostic strategies depend on non-standardized workup, and the causes of myocardial infarction with non-obstructive coronary arteries remain unclear for some patients. Intracoronary imaging is recommended for detecting the missed causes by coronary angiography. Myocardial infarction with non-obstructive coronary arteries is a heterogeneous entity; a meta-analysis of myocardial infarction with non-obstructive coronary artery studies demonstrated that all-cause mortality rate at 1 year is 4.7%, and its prognosis is not so favourable. Case summary: A 62-year-old man without remarkable medical history complained of acute chest pain at rest, which resolved at his arrival. Although echocardiography and electrocardiogram exhibited normal findings, the concentration of high-sensitive cardiac troponin T increased up to 0.384 from 0.04 ng/mL. Coronary angiography was performed, and mild stenosis of the proximal right coronary artery was detected. He was discharged without catheter intervention and medications as he reported no symptoms. He returned 8 days later because of inferoposterior ST-segment elevation myocardial infarction with ventricular fibrillation. Emergent coronary angiography showed that the mild stenosis of the proximal right coronary artery had progressed to total occlusion. Optical coherence tomography after thrombectomy revealed rupture of the thin-cap fibroatheroma and protruding thrombus. Discussion: Patients presenting with myocardial infarction with non-obstructive coronary arteries and plaque disruption and/or thrombus detected by optical coherence tomography do not show normal coronaries on coronary angiography. Aggressive investigation into plaque disruption using intracoronary imaging is recommended even if coronary angiography demonstrates mild stenosis to prevent a fatal attack for suspicious cases of myocardial infarction with non-obstructive coronary arteries.

Rationale and design of the TACTICS registry: Optical coherence tomography guided primary percutaneous coronary intervention for patients with acute coronary syndrome.

BACKGROUND: Recent retrospective investigations have suggested that optical coherence tomography (OCT) enables the diagnosis of underlying acute coronary syndrome (ACS) causes such as plaque rupture, plaque erosion, and calcified nodule. The relationships of these etiologies with clinical outcomes, and the clinical utility of OCT-guided primary percutaneous coronary intervention (PCI) are not systematically studied in real-world ACS treatment settings. METHODS: The TACTICS registry is an investigator-initiated, prospective, multicenter, observational study to be conducted at 21 hospitals in Japan. A total of 700 patients with ACS (symptom onset within 24 h) undergoing OCT-guided primary PCI will be enrolled. The primary endpoint of the study is to identify the underlying causes of ACS using OCT-defined morphological assessment of the culprit lesion. The key secondary clinical endpoints are hazard ratios of the composite of cardiovascular death, non-fatal myocardial infarction, heart failure, or ischemia-driven revascularization in patients with underlying etiologies at the 12- and 24-month follow-ups. The feasibility of OCT-guided primary PCI for ACS will be assessed by the achievement rates of optimal post-procedural results and safety endpoints. CONCLUSION: The TACTICS registry will provide an overview of the underlying causes of ACS using OCT, and will reveal any difference in clinical outcomes depending on the underlying causes. The registry will also inform on the feasibility of OCT-guided primary PCI for patients with ACS.

Device for retrieval of vena cava filter with combination of a multi-loop snare and Amplatz catheter.

A 25-year-old woman diagnosed as having a non-massive pulmonary embolism and deep vein thrombosis from the right superficial femoral to the right common iliac vein was treated by deployment of a DENALI® Vena Cava Filter. Filter retrieval was attempted 6 months later using a BARD snare retrieval kit. However, the conventional technique was unsuccessful because of a tilt and attachment of the filter head to the vessel wall. Hence, we passed an EN Snare Endovascular Snare System through an Amplatz Left 1 guiding catheter to successfully penetrate the attached portion of the filter hook and vessel wall. This combination provided controlled direction and a strong backup force that helped capture and retrieve the filter. This technique could be an alternative method to retrieve inferior vena cava filter with severe tilt and tight attachment to the vena cava wall when the conventional technique is unsuccessful.

Helicopter emergency medical service for patients with acute coronary syndrome: selection validity and impact on clinical outcomes.

Helicopter emergency medical service (HEMS) has the potential to improve prognosis for acute coronary syndrome (ACS). However, adequacy and effectiveness of HEMS have not been fully evaluated. A total of 862 ACS patients transferred by emergency medical services were divided into two groups: patients transferred by HEMS (n = 171) or by ground ambulance (GA; n = 691). Among them, angiography images for 718 patients (149 in HEMS and 569 in GA group) and optical coherence tomography (OCT) images for 374 patients (75 in HEMS and 299 in GA groups) were analyzed. Additional analysis to compare 2-year cardiac mortality between groups was conducted following propensity score matching to adjust for inter-group differences. ST-segment elevation myocardial infarction (81% vs. 66%, p < 0.001) and cardiogenic shock (Killip IV; 20% vs. 10%, p < 0.001) at admission were more prevalent in HEMS than GA group. Time from admission to balloon angioplasty was shorter in HEMS group (median 54 min vs. 69 min, p < 0.001). Antegrade coronary flow was worse in HEMS group (TIMI flow grade 0 or 1; 68% vs. 51%, p < 0.001). Plaque rupture was more frequently detected by OCT in HEMS group (68% vs. 49%, p = 0.029). Following propensity score matching, the incidence of cardiac death was significantly lower in HEMS group (6.3% vs. 14.9%, p = 0.019). In conclusion, severe ACS patients requiring early reperfusion were appropriately triaged and transferred more rapidly by HEMS. Lower mortality in HEMS group after propensity score matching suggests that HEMS may improve cardiac mortality in ACS patients.

Age and Phenotype of Patients With Plaque Erosion.

Background A recent study reported that the outcome of patients with plaque erosion treated with stenting is poor when the underlying plaque is lipid rich. However, the detailed phenotype of patients with plaque erosion, particularly as related to different age groups, has not been systematically studied. Methods and Results Patients with acute coronary syndromes caused by plaque erosion were selected from 2 data sets. Demographic, clinical, angiographic, and optical coherence tomography findings of the culprit lesion were compared between 5 age groups. Among 579 erosion patients, male sex and current smoking were less frequent, and hypertension, diabetes, and chronic kidney disease were more frequent in older patients. ST-segment-elevation myocardial infarction was more frequent in younger patients. Percentage of diameter stenosis on angiogram was greater in older patients. The prevalence of lipid-rich plaque (27.3% in age <45 years and 49.4% in age ≥75 years, P<0.001), cholesterol crystal (3.9% in age <45 years and 21.8% in age ≥75 years, P=0.027), and calcification (5.5% in age <45 years and 54.0% in age ≥75 years, P<0.001) increased with age. After adjusting risk factors, younger patients were associated with the presence of thrombus, and older patients were associated with greater percentage of diameter stenosis and the presence of lipid-rich plaque and calcification. Conclusions The demographic, clinical, angiographic, and plaque phenotypes of patients with plaque erosion distinctly vary depending on age. This may affect the clinical outcome in these patients. Registration URL: https://www.clinicaltrials.gov. Unique identifiers: NCT03479723, NCT02041650.

Coronary plaque and clinical characteristics of South Asian (Indian) patients with acute coronary syndromes: An optical coherence tomography study.

BACKGROUND: South Asians, and Indians in particular, are known to have a higher incidence of premature atherosclerosis and acute coronary syndromes (ACS) with worse clinical outcomes, compared to populations with different ethnic backgrounds. However, the underlying pathobiology accounting for these differences has not been fully elucidated. METHODS: ACS patients who had culprit lesion optical coherence tomography (OCT) imaging were enrolled. Culprit plaque characteristics were evaluated using OCT. RESULTS: Among 1315 patients, 100 were South Asian, 1009 were East Asian, and 206 were White. South Asian patients were younger (South Asians vs. East Asians vs. Whites: 51.6 ± 13.4 vs. 65.4 ± 11.9 vs. 62.7 ± 11.7; p < 0.001) and more frequently presented with ST-segment elevation myocardial infarction (STEMI) (77.0% vs. 56.4% vs. 35.4%; p < 0.001). On OCT analysis after propensity group matching, plaque erosion was more frequent (57.0% vs. 38.0% vs. 50.0%; p = 0.003), the lipid index was significantly greater (2281.6 [1570.8-3160.6] vs. 1624.3 [940.9-2352.4] vs. 1303.8 [1090.0-1757.7]; p < 0.001), and the prevalence of layered plaque was significantly higher in the South Asian group than in the other two groups (52.0% vs. 30.0% vs. 34.0%; p = 0.003). CONCLUSIONS: Compared to East Asians and Whites, South Asians with ACS were younger and more frequently presented with STEMI. Plaque erosion was the predominant pathology for ACS in South Asians and their culprit lesions had more features of plaque vulnerability. CLINICAL TRIAL REGISTRATION: http://www.clinicaltrials.gov, NCT03479723.

Optical Coherence Tomography of Coronary Plaque Progression and Destabilization: JACC Focus Seminar Part 3/3.

The development of optical coherence tomography (OCT) has revolutionized our understanding of coronary artery disease. In vivo OCT research has paralleled with advances in computational fluid dynamics, providing additional insights in the various hemodynamic factors influencing plaque growth and stability. Recent OCT studies introduced a new concept of plaque healing in relation to clinical presentation. In addition to known mechanisms of acute coronary syndromes such as plaque rupture and plaque erosion, a new classification of calcified plaque was recently reported. This review will focus on important new insights that OCT has provided in recent years into coronary plaque development, progression, and destabilization, with a focus on the role of local hemodynamics and endothelial shear stress, the layered plaque (signature of previous subclinical plaque destabilization and healing), and the calcified culprit plaque.

Impact of Low Body Mass Index on Features of Coronary Culprit Plaques and Outcomes in Patients With Acute Coronary Syndrome.

The mechanisms behind poorer cardiac outcomes in underweight patients with acute coronary syndrome (ACS) are not understood and features of coronary culprit lesions in underweight ACS patients have not been fully examined. A total of 1,683 patients with ACS were divided into 4 groups according to body mass index (BMI): <18.5 (n = 73), 18.5 to 24.9 (n = 995), 25 to 29.9 (n = 488), and ≥30 (n = 117). Angiography and optical coherence tomography (OCT) images were analyzed for 1,428 of these patients who had primary percutaneous coronary intervention (PCI) and 838 who had primary PCI with OCT guidance, respectively. Diabetes (p <0.001), hypertension (p <0.001), and dyslipidemia (p <0.001) were less prevalent in BMI <18.5. Statin prescription at discharge was less frequent in the BMI <18.5 group (p <0.001). Quantitative coronary angiography analyses revealed smaller reference vessel (p = 0.001) and minimum lumen diameters after PCI (p = 0.019) and OCT revealed longer lipidic plaque length (p = 0.029) in the BMI <18.5 group. Kaplan-Meier analyses revealed higher rates of cardiac mortality (p <0.001) and major bleeding (p = 0.034) during the 2-year follow-up in the BMI <18.5 group. After adjusting for traditional cardiovascular risk factors, BMI <18.5 independently predicted 2-year cardiac mortality (hazard ratio 1.917 [95% confidence interval [1.082 to 3.397], p = 0.026). In conclusion, being underweight contributed to poorer cardiac outcomes in established ACS population. Smaller minimum lumen diameter after PCI and further progressed atherosclerosis at the culprit lesions despite their lower prevalence of comorbid metabolic risk factors may be related partly to poorer cardiac outcomes.

Vulnerable atherosclerotic plaque features: findings from coronary imaging.

Pathological studies have suggested that features of vulnerable atherosclerotic plaques likely to progress and lead to acute cardiovascular events have specific characteristics. Given the progress of intravascular coronary imaging technology, some large prospective studies have detected features of vulnerable atherosclerotic plaques using these imaging modalities. However, the rate of cardiovascular events, such as acute coronary syndrome, has been found to be considerably reduced in the limited follow-up period available in the statin era. Additionally, not all disrupted plaques lead to thrombus formation with clinical presentation. If sub-occlusive or occlusive thrombus formation does not occur, a thrombus on a disrupted plaque will organize without any symptoms, forming a "healed plaque". Although vulnerable plaque detection using intracoronary imaging is focused on "thin-cap fibroatheroma" leading to plaque rupture, superficial plaque erosion is increasingly recognized; however, the underlying mechanism of thrombus formation on eroded plaques is not well understood. One of intravascular imaging, optical coherence tomography (OCT) has the highest image resolution and has enabled detailed characterization of the plaque in vivo. Here, we reviewed the status and limitations of intravascular imaging in terms of detecting vulnerable plaque through mainly OCT studies. We suggested that vulnerable plaque should be reconsidered in terms of eroded plaque and healed plaque and that both plaque and circulating blood should be assessed in greater detail accordingly.