Long-term clinical outcomes in patients with untreated non-culprit intermediate coronary lesion and evaluation of predictors by using virtual histology-intravascular ultrasound; a prospective cohort study.

BACKGROUND: It is uncertain whether the coronary lesion with intermediate stenosis is more likely to cause cardiovascular events than a normal or minimal lesion. We conducted a single-center, prospective cohort study to identify long-term clinical outcomes of patients with untreated non-culprit intermediate lesion and evaluate its predictor of cardiovascular events by using virtual histology-intravascular ultrasound (VH-IVUS). METHODS: Subjects with non-culprit intermediate lesion underwent VH-IVUS were prospectively registered after percutaneous coronary intervention at the culprit lesion. Intermediate lesion was defined as 30 to 70% stenosis in coronary angiography and primary outcome was an occurrence of major adverse cardiovascular events (MACE) defined as all-cause death, intermediate lesion revascularization (InLR), minimal lesion revascularization (MnLR, unplanned revascularization elsewhere in the target vessel or in other coronary arteries which looked normal or minimal stenosis), cerebrovascular events, or non-fatal myocardial infarction (MI). The mean follow-up period was 4.2 years. RESULTS: Total 25 MACE, approximately 7% incidence annually, were identified during a follow-up period in 86 patients with 89 intermediate lesions. InLR (n = 13) was a most common event followed by MnLR (n = 6), non-fatal MI (n = 4), all-cause death (n = 3), and cerebrovascular events (n = 1). Diameter stenosis (OR 1.07, 95% CI 1.01-1.12, p = 0.015), plaque burden (PB, OR 1.07, 95% CI 1.00-1.15, p = 0.040), fibrofatty area (FFA, OR 1.61, 95% CI 1.10-2.38, p = 0.016), PB ≥ 70% (OR 3.93, 95% CI 1.28-12.07, p = 0.018), and area stenosis ≥ 50% (OR 2.94, 95% CI 1.01-8.56, p = 0.042) showed significant relationships with an occurrence of MACE. In multivariable Cox-proportional hazard analysis, FFA in intermediate lesion was an only independent predictor of MACE (HR 1.36, 95% CI 1.05-1.77, p = 0.019). CONCLUSIONS: Untreated intermediate lesions had a significantly higher chance for requiring revascularization compared with a normal or minimal lesion. And also, a large FFA in intermediate lesion was a significant predictor of cardiovascular events and which finding was mainly driven by coronary-related events, in particularly intermediate lesion progression.

A Rare Case of Stroke in a 76-Year-Old Woman: Left Atrial Papillary Fibroelastoma as the Culprit.

BACKGROUND Papillary fibroelastoma is the most common type of benign primary cardiac tumor and is usually asymptomatic. However, tumor fragments or surface thrombus can embolize and cause transient ischemic attacks, strokes, or myocardial infarction. This report describes a 76-year-old woman who presented with dysarthria and right-sided weakness due to a stroke associated with a left atrial papillary fibroelastoma. CASE REPORT A 76-year-old woman visited the Emergency Department because she had right-sided weakness and dysarthria from 12 h ago. Brain magnetic resonance image was done at the Emergency Department, showing multiple small embolic, acute infarction in left basal ganglia and fronto-temporo-parietal lobes. Transthoracic and transesophageal echocardiogram showed a hypermobile echogenic mass (0.8×1.5 cm) with villous surface on the orifice of left atrial appendage. Twenty-four-hour Holter monitoring was performed to evaluate the cause of cerebral infarction, and there was no paroxysmal atrial fibrillation. Thoracic computed tomography angiography also showed a sea anemone-shaped mass around the left atrial appendage. Cardiac tumor excision was done via a lower partial sternotomy. Histopathologic analysis showed multiple delicate fronds, and the avascular fibroelastic cores were lined by a single layer of CD31-positive endothelial cells. Histopathologic findings were consistent with papillary fibroelastoma. The patient was discharged without any other complications on day 30 of hospitalization. CONCLUSIONS This case highlights the importance of cardiac imaging in patients with acute stroke, including transthoracic and transesophageal echocardiography, which can show the typical imaging features of papillary fibroelastoma and other intracardiac sources of embolus.

Toxocariasis-Associated Acute Perimyocarditis with Cardiogenic Shock: A Case Report.

BACKGROUND Toxocariasis is an infection due to ingestion of the helminth parasite larvae found in dogs (Toxocara canis) or cats (Toxocara cati). Symptoms vary from being asymptomatic to shock, depending on the organ invaded by the parasite. However, cardiac involvement with shock in toxocariasis is very rare. CASE REPORT A 21-year-old woman without any history of underlying conditions visited the Emergency Department because of epigastric pain, vomiting, headache, and dizziness. Her blood pressure was 80/60 mmHg. Computed tomography (CT) of the brain showed no abnormal lesions. The abdominal-pelvic CT with contrast showed right pleural effusion, pericardial effusion, and focal ascites in the pelvic cavity. Laboratory tests revealed an elevation of eosinophils (40%) and cardiac enzymes (creatinine kinase-MB 27.6 ng/mL, high-sensitive cardiac troponin T 1.21 ng/mL). The transthoracic echocardiogram showed left ventricular systolic dysfunction (ejection fraction 44%) and moderate pericardial effusion. She was presumptively diagnosed with hypereosinophilic perimyocarditis and admitted to the Intensive Care Unit for shock. The pericardial effusion increased during treatment; therefore, pericardiocentesis was performed. Analysis of the pericardial effusion showed eosinophilia (eosinophils 90%) and the serologic test for parasites was positive for Toxocara and Sparganum. A combination therapy of albendazole, praziquantel, and corticosteroid resolved the pericardial effusion and the peripheral blood eosinophil count normalized. She was discharged without any other complications. At Outpatient Clinic follow-ups and observations over the next 2 years there were no abnormal findings, including pericardial effusion or eosinophilia. CONCLUSIONS Toxocariasis rarely causes perimyocarditis with cardiogenic shock. Patients who present with pericardial effusion and eosinophilia need to be evaluated for parasitic infection.

Ten-year clinical outcomes of an intermediate coronary lesion; prognosis and predictors of major adverse cardiovascular events.

AIMS: The natural history of intermediate coronary lesions (30 to 70% angiographic stenosis) and the prognostic predictors in predicting very long-term clinical outcomes is unknown. METHODS: Patients (n = 82, mean 60 years old) with intermediate non-culprit coronary lesions (NCL, n = 86), evaluated by virtual histology-intravascular ultrasound (VH-IVUS), were followed for 10 years. Major adverse cardiovascular events (MACE; all-cause death, myocardial infarction, stroke, and revascularization) were collected over follow-up period and stratified by culprit lesion (CL)-related, NCL-related and indeterminate/unrelated to CL or NCL lesions. NCL-related MACE was further stratified into intermediate and minimal NCL-related events. RESULTS: Twenty two (25.6%) out of 86 intermediate NCL were associated with MACE in 20/82 (24.4%) study patients. Ten-year cumulative intermediate NCL-related MACE rate was twice (25.6% vs. 12.8%) compared to treated culprit lesion (CL)-related MACE. Ten-year cumulative revascularization rate of the intermediate NCL lesions was similar (17.4% vs. 15.1%) to those of CL, but higher than that of minimal (stenosed <30% at baseline) NCL (8.1%). Important intermediate NCL VH-IVUS predictor for MACE was area stenosis ≥50%, and for revascularization were percent diameter stenosis, plaque burden ≥70%, and fibrofatty area. CONCLUSIONS: Ten-year MACE rate of intermediate NCL was double that of CL and ten-year revascularization rate of intermediate NCL was similar or slightly higher than that of CL. VH-IVUS may play an important role in determining the very long-term clinical outcomes in patients with intermediate NCL. This study suggests that Intermediate NCL can be safely followed up in terms of revascularization risk.

Rationale of decreasing low-density lipoprotein cholesterol below 70 mg/dL in patients with coronary artery disease: A retrospective virtual histology-intravascular ultrasound study.

BACKGROUND: The associations between statin and coronary plaque compositional changes were re-ported according to the use of high dose or not. An evaluation of the impact of low-density lipoprotein cholesterol (LDL-C) < 70 mg/dL by using real world dosages of statin on coronary plaque composition was undertaken. METHODS: The study subjects consisted of 61 patients (mean 59.9 years old, 45 males) who underwent percutaneous coronary intervention, baseline and follow-up (F/U; mean 8.4 months) virtual histology- -intravascular ultrasound (VH-IVUS) examination. Change of plaque composition at peri-stent area, which was selected in order to measure the identical site at F/U study, was compared according to the F/U LDL-C level. RESULTS: Body mass index, prevalence of dyslipidemia, baseline total cholesterol and baseline LDL-C were significantly lower in F/U LDL-C < 70 mg/dL group (14 segments in 10 patients) than F/U LDL-C ≥ 70 mg/dL group (79 segments in 51 patients). F/U high-density lipoprotein cholesterol (HDL-C, OR 1.06, 95% CI 1.00-1.11, p = 0.054) and F/U LDL-C < 70 mg/dL (OR 3.43, 95% CI 0.97-12.17, p = 0.056) showed strong tendency of regression of necrotic core volume (NCV) ≥ 10%. In multivariable logis-tic regression analysis, F/U HDL-C (OR 1.07, 95% CI 1.01-1.14, p = 0.020) and F/U LDL-C < 70 mg/dL (OR 8.02, 95% CI 1.58-40.68, p = 0.012) were the independent factors for regression of NCV ≥ 10%. CONCLUSIONS: Follow-up LDL-C level < 70 mg/dL with any types of statins and increase of HDL-C were associated with regression of NCV ≥ 10% in patients with coronary artery disease.

In-stent restenosis-prone coronary plaque composition: A retrospective virtual histology-intravascular ultrasound study.

BACKGROUND: The mechanism of in-stent restenosis (ISR) is multifactorial, which includes biological, mechanical and technical factors. This study hypothesized that increased inflammatory reaction, which is known to be an important atherosclerotic process, at a culprit lesion may lead to higher restenosis rates. METHODS: The study population consisted of 241 patients who had undergone percutaneous coronary intervention with virtual histology-intravascular ultrasound (VH-IVUS) and a 9-month follow-up coronary angiography. Compared herein is the coronary plaque composition between patients with ISR and those without ISR. RESULTS: Patients with ISR (n = 27) were likely to be older (66.2 ± 9.5 years vs. 58.7 ± 11.7 years, p = 0.002) and have higher levels of high-sensitivity C-reactive protein (hs-CRP, 1.60 ± 3.59 mg/dL vs. 0.31 ± 0.76 mg/dL, p < 0.001) than those without ISR (n = 214). VH-IVUS examination showed that percent necrotic core volume (14.3 ± 8.7% vs. 19.5 ± 9.1%, p = 0.005) was higher in those without ISR than those with ISR. Multivariate analysis revealed that hs-CRP (odds ratio [OR] 3.334, 95% con-fidence interval [CI] 1.158-9.596, p = 0.026) and age (OR 3.557, 95% CI 1.242-10.192, p = 0.018) were associated with ISR. CONCLUSIONS: This study suggests that ISR is not associated with baseline coronary plaque composition but is associated with old age and increased expression of the inflammatory marker of hs-CRP. (Cardiol J 2018; 25, 1: 7-13).

Analysis of Plaque Composition in Coronary Chronic Total Occlusion Lesion Using Virtual Histology-Intravascular Ultrasound.

BACKGROUND AND OBJECTIVES: Success rates of chronic total occlusion (CTO) percutaneous coronary intervention (PCI) have recently been reported to range from 80% to 90%. A better understanding of the pathologic characteristics of the CTO lesion may helpful to improving CTO PCI success rates. We evaluated the CTO lesion in patients with stable angina (SA) by virtual histology-intravascular ultrasound (VH-IVUS). SUBJECTS AND METHODS: The study population consisted of 149 consecutive patients with SA underwent VH-IVUS examination. We analyzed demographic and VH-IVUS findings in 22 CTO patients (17 males; mean, 62.3 years old) compared with 127 non-CTO patients (82 males; mean, 61.3 years old). RESULTS: A significantly lower ejection fraction (57.6±13.0% vs. 65.4±8.8%, p=0.007) was detected in the CTO group compared with the non-CTO group. Reference vessel lumen area of the proximal and distal segment was significantly less in CTO group than in non-CTO group. The lesion length of the CTO group was significantly longer than those of the non-CTO group (24.4±9.6 mm vs. 17.2±7.4 mm, p<0.001). Total atheroma volume (224±159 mm(3) vs. 143±86 mm(3), p=0.006) and percent atheroma volume (63.2±9.6% vs. 55.8±8.5%, p=0.011) of the CTO group were also significantly greater than those of non-CTO group. However, the lesion length adjusted plaque composition of the CTO group was not significantly different compared with that of the non-CTO group. CONCLUSION: CTO lesions had a longer lesion length and greater plaque burden than the non-CTO lesion in patients with SA. However, lesion length adjusted plaque composition showed similar between the two groups. These results support that plaque characteristics of CTO lesions are similar to non-CTO lesions in patients with SA.

Radiographic Assessment of Effect of Congenital Monosegment Synostosis of Lower Cervical Spine between C2-C6 on Adjacent Mobile Segments.

STUDY DESIGN: A prospective radiographic study of cervical spine with congenital monosegment fusion. PURPOSE: To evaluate the effect of cervical synostosis on adjacent segments and the vertebral morphology. OVERVIEW OF LITERATURE: There are numerous clinical studies of adjacent segment disease (ASD) after monosegment surgical fusion. However, there was no report on ASD in the cervical spine with congenital monosegment synostosis. METHODS: Radiograms of 52 patients, aged 5 to 90 years, with congenital monosegment synostosis (CMS) between C2 and C6, who complained of neck/shoulder discomfort or pain were studied. 51 were normally aligned and one was kyphotically aligned. RESULTS: Spondylosis was not found in the patients below 35 years of age. Only 12 out of 24 patients with normally aligned C2-3 synostosis had spondylosis in 19 more caudal segments, and only one at C3-4. A patient with kyphotic C2-3 had spondylolysis at C3-4. In 8 patients with C3-4 synostosis, spondylosis was found in only 9 caudal segments (4 at C4-5, 4 at C5-6, and 1 at C6-7). The caudate C4-5 disc was the most liable to degenerate in comparison with other caudate segments. Caudal corporal flaring and inwaisting of the synostotic vertebra were the features that were the most evident. In 2 of 9 C4-5 and 7 out of 10 C5-6 synostosis patients, spondylosis was found at the two adjacent cephalad and caudate segments, respectively. Only corporal inwaisting without flaring was found. In all cases, spondylosis was confined to the adjacent segments. More advanced spondylosis was found in the immediate caudal segment than the cephalad one. CONCLUSIONS: It is concluded that spondylosis at the mobile segments in a synostotic spine is thought to be a fusion-related pathology rather than solely age-related disc degeneration. Those data suggested that CMS definitely precipitated the disc degeneration in the adjacent segments.

Effect of correction of the contractured flexed osteoarthritic knee on the sagittal alignment by total replacement.

STUDY DESIGN: A prospective analysis of an adaptive change of the spinopelvic alignment after total knee arthroplasty. PURPOSE: To evaluate the effect of correction of the contractured knee in flexion on the spinopelvic alignment by total knee arthroplasty. OVERVIEW OF LITERATURE: Flexion contracture of the knee joint may affect the body posture and precipitate the symptoms in the lumbar spine, which is known as the 'knee-spine syndrome'. METHODS: Fifteen patients who could be followed at least over 12 months were used in this study. Neutral whole spine lateral standing radiograms taken at certain intervals were analyzed. The subjects were divided into two groups (group A, the patients who obtained over 10° correction; group B, the others). The sacral slope, the pelvic tilt and the pelvic incidence were measured preoperatively and at 12 months and thereafter postoperatively in all the patients. Also, the thoracic kyphosis, lumbar lordosis, and lumbosacral angle were measured, including the spinal sagittal balance, S1 overhang and spino-sacral angle. RESULTS: The average correction of the contractured knee in flexion were 13.8° in group A and 2.7° in group B. The median of changes of the sacral slope were 4.2° in group A and -0.4° in group B. These results revealed that there was a significant increase of the sacral slope for group A (p=0.001). However, there were no significant differences between the other parameters. CONCLUSIONS: The sacral slope appears to be affected by the change of the flexion contracture after total knee arthroplasty.

Hypercholesterolemia and in-vivo coronary plaque composition in patients with coronary artery disease: a virtual histology - intravascular ultrasound study.

BACKGROUND AND OBJECTIVES: Hypercholesterolemia is a key factor in the development of atherosclerosis. We sought to evaluate the relation between hypercholesterolemia and plaque composition in patients with coronary artery disease. SUBJECTS AND METHODS: Study subjects consisted of 323 patients (mean 61.5 years, 226 males) who underwent coronary angiography and virtual histology-intravascular ultrasound examination. Patients were divided into two groups according to total cholesterol level: hypercholesterolemic group (≥200 mg/dL, n=114) and normocholesterolemic group (<200 mg/dL, n=209). RESULTS: Hypercholesterolemic patients were younger (59.7±13.3 years vs. 62.6±11.5 years, p=0.036), than normocholesterolemic patients, whereas there were no significant differences in other demographics. Hypercholesterolemic patients had higher corrected necrotic core volume (1.23±0.85 mm(3)/mm vs. 1.02±0.80 mm(3)/mm, p=0.029) as well as percent necrotic core volume (20.5±8.5% vs. 18.0±9.2%, p=0.016) than normocholesterolemic patients. At the minimal lumen area site, percent necrotic core area (21.4±10.5% vs. 18.4±11.3%, p=0.019) and necrotic core area (1.63±1.09 mm(2) vs. 1.40±1.20 mm(2), p=0.088) were also higher than normocholesterolemic patients. Multivariate linear regression analysis showed that total cholesterol level was an independent factor of percent necrotic core volume in the culprit lesion after being adjusted with age, high density lipoprotein-cholesterol , hypertension, diabetes mellitus, smoking and acute coronary syndrome (beta 0.027, 95% confidence interval 0.02-0.053, p=0.037). CONCLUSION: Hypercholesterolemia was associated with increased necrotic core volume in coronary artery plaque. This study suggests that hypercholesterolemia plays a role in making plaque more complex, which is characterized by a large necrotic core, in coronary artery disease.

Discrepancy of calcium detection between gray scale intravascular ultrasound and spectral analysis of radiofrequency data.

BACKGROUND: We evaluated discrepancy of calcium detection between gray scale intravascular ultrasound (IVUS) and virtual histology (VH)-IVUS and the association between coronary calcium and plaque composition. METHODS: Study population consisted of 162 consecutive patients who underwent percutaneous coronary intervention with VH-IVUS study. Subjects were divided into 3 groups based on gray scale IVUS findings; No calcification group (n=50), spotty group (n=56) who had a lesion containing only small calcium deposits within an arc <90° and diffuse group (n=56) who had a diffuse calcified lesion with an arc ≥ 90° in ≥ 1 cross-sectional image of the lesion. RESULTS: No calcification group was younger than spotty and diffuse groups (54.4 ± 13.0 years vs. 61.1 ± 10.7 years and 64.2 ± 9.9 years, p=0.011 and p<0.001, respectively). No calcification group had some degree of dense calcium (5. 7 ± 6.9 mm(3)) by VH-IVUS analysis. Furthermore, calcified volume by VH-IVUS in no calcification group was similar to those in spotty group (5.7 ± 6.9 mm(3) vs. 5.4 ± 4.4mm(3)). Dense calcium volume was correlated directly with plaque volume (r=0.65, p<0.001), fibrous volume (r=0.54, p<0.001), fibro-fatty volume (r=0.29, p<0.001) and lipid core volume (r=0.77, p<0.001). In multiple regression analysis, lipid core volume (ß=0.287, 95% confidence interval (CI) 0.187-0.388, p<0.001) was an independent predictor of dense calcium volume. CONCLUSIONS: This study showed that coronary calcium can be present even if invisible in gray scale IVUS and associated with lipid core volume, which is a characteristic of plaque vulnerability.

Impact of plaque composition on long-term clinical outcomes in patients with coronary artery occlusive disease.

BACKGROUND AND OBJECTIVES: It is unclear which plaque component is related with long-term clinical outcomes in patients with coronary artery occlusive disease (CAOD). We assessed the relationship between plaque compositions and long-term clinical outcomes in those patients. SUBJECTS AND METHODS: The study subjects consisted of 339 consecutive patients (mean 61.7±12.2 years old, 239 males) who underwent coronary angiogram and a virtual histology-intravascular ultrasound examination. Major adverse cardiac and cerebrovascular events (MACCE), including all-cause death, non-fatal myocardial infarction, cerebrovascular events, and target vessel revascularization were evaluated during a mean 28-month follow-up period. RESULTS: Patients with high fibrofatty volume (FFV, >8.90 mm(3), n=169) had a higher incidence of MACCE (25.4% vs. 14.7%, p=0.015), male sex (75.7% vs. 65.3%, p=0.043), acute coronary syndrome (53.3% vs. 35.9%, p=0.002), multivessel disease (62.7% vs. 41.8%, p<0.001) and post-stent slow flow (10.7% vs. 2.4%, p=0.002) than those with low FFV (FFV≤8.90 mm(3), n=170). Other plaque composition factors such as fibrous area/volume, dense calcified area/volume, and necrotic core area/volume did not show any impact on MACCE. Cardiogenic shock {hazard ratio (HR)=8.44; 95% confidence interval (CI)=3.00-23.79; p<0.001} and FFV (HR=1.85; 95% CI=1.12-3.07; p=0.016) were the independent predictors of MACCE by Cox regression analysis. Thin-cap fibroatheroma, necrotic core area, and necrotic core volume were not associated with MACCE. CONCLUSION: FFV of a culprit lesion was associated with unfavorable long-term clinical outcomes in patients with CAOD.

Fibro-Fatty Component is Important for the Long-Term Clinical Events in Patients Who Have Undergone Primary Percutaneous Coronary Intervention.

BACKGROUND AND OBJECTIVES: We evaluated which plaque components are associated with long-term clinical events in patients who underwent primary percutaneous coronary intervention (PCI). SUBJECTS AND METHODS: The study subjects consisted of 57 consecutive patients (mean age, 58.5±14.5 years; 45 males) who underwent primary PCI and a virtual histology-intravascular ultrasound examination. Major adverse cardiac events (MACEs) including death, acute myocardial infarction, stroke, and revascularization were evaluated during the mean 28 month follow-up period. RESULTS: Patients with high fibro-fatty volume (FFV >13.4 mm(3), n=29; mean age, 61.3 years) had a lower ejection fraction (52.7% vs. 59.4%, p=0.022), a higher incidence of multi-vessel disease (69.0% vs. 28.6%, p=0.002), larger plaque area (25.7 mm(2) vs. 15.9 mm(2), p<0.001), and larger plaque volume (315 mm(3) vs. 142 mm(3), p<0.001) than those with a low FFV (≤13.4 mm(3), n=28; mean age, 55.6 years). Patients with high FFV had a significantly higher incidence (32.1% vs. 8.3%, p=0.036) of MACE than those with low FFV. When we divided the study population according to the necrotic core volume (NCV), fibrous volume, or dense calcified volume, no significant findings in terms of demographics and MACE rates were observed. A Cox regression analysis revealed that the independent factor for MACE was FFV (hazard ratio, 6.748; 95% confidence interval, 1.168-38.971, p=0.033) in this study population. CONCLUSION: The coronary plaque component, particularly FFV, but not NCV, was important in long-term clinical outcomes in patients who underwent primary PCI.

Positive Vascular Remodeling in Culprit Coronary Lesion is Associated With Plaque Composition: An Intravascular Ultrasound-Virtual Histology Study.

BACKGROUND AND OBJECTIVES: The relationship between the positive remodeling (PR) of a coronary artery and plaque composition has been studied only in a relatively small number of study population or non-culprit lesion. We evaluated the association between coronary plaque composition and coronary artery remodeling in a relatively large number of culprit lesions. SUBJECTS AND METHODS: The study population consisted of 325 consecutive patients with coronary artery disease that underwent intravascular ultrasound-virtual histology examination in a culprit lesion. The remodeling index (RI) was calculated as the lesion external elastic membrane (EEM) area divided by the average reference EEM area. RESULTS: The lesions with PR (RI>1.05, n=97, mean RI=1.19±0.12) had a higher fibrous volume/lesion length (3.85±2.12 mm(3)/mm vs. 3.04±1.79 mm(3)/mm, p=0.003) and necrotic core volume/lesion length (1.26±0.89 mm(3)/mm vs. 0.90±0.66 mm(3)/mm, p=0.001) than those with negative remodeling (NR) (RI<0.95, n=132, mean RI=0.82±0.09). At the minimal luminal area site, the lesions with PR had a higher fibrous area (5.81±3.17 mm(2) vs. 3.61±2.30 mm(2), p<0.001), dense calcified area (0.73±0.69 mm(2) vs. 0.46±0.43 mm(2), p=0.001), and necrotic core area (1.93±1.33 mm(2) vs. 1.06±0.91 mm(2), p<0.001) than those with NR. RI showed significant positive correlation with fibrous volume/lesion length (r=0.173, p=0.002), necrotic core volume/lesion length (r=0.188, p=0.001), fibrous area (r=0.347, p<0.001), fibrofatty area (r=0.111, p=0.036), dense calcified area (r=0.239, p<0.001), and necrotic core area (r=0.334, p<0.001). Multivariate analysis showed that the independent factor for PR was the necrotic core volume/lesion length (beta=0.130, 95% confidence interval; 0.002-0.056, p=0.037) over the entire lesion. CONCLUSION: This study suggests that PR in a culprit lesion is associated with the necrotic core volume in the entire lesion, which is a characteristic of vulnerable plaque.