The Relationship Between Volumetric Plaque Components and Classical Cardiovascular Risk Factors and the Metabolic Syndrome

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.

Comparison of Atherosclerotic Plaque Compositions in Diabetic and Non-diabetic Patients

INTRODUCTION

Diabetes mellitus is one of the major risk factors for coronary artery disease. Intravascular ultrasound (IVUS) imaging has an important role in the evaluation of atherosclerotic coronary artery disease. The aim of the study was to investigate the potential link between diabetes mellitus and plaque vulnerability in patients with coronary artery disease.

METHODS

In total, 26 patients with acute coronary syndrome (eight with diabetes mellitus) and 34 with stable angina pectoris (16 with diabetes mellitus) constituted the study population. Patients underwent IVUS ultrasound and virtual histology (VH)-IVUS imaging during routine diagnostic catheterization procedures. A total of 70 plaques in 60 patients were examined.

RESULTS

Patients with diabetes mellitus had a significantly greater percentage of fibrofatty components in the minimal lumen area (MLA) (17 ± 12 in diabetics; 12 ± 6 in non-diabetics; p=0.06). Thin-cap fibroatheromas were more frequent in patients with diabetes mellitus (72% versus 45%; p=0.012). There was a positive correlation between the presence of attenuated plaque and hemoglobin A1C (HbA1c) levels as well (7.09 ± 1.66 versus 6.02 ± 1.00; p=0.011). Patients with HbA1C ≥7.5% also had the highest prevalence of attenuated plaque.

CONCLUSION

As shown by VH-IVUS, the prevalence of vulnerable plaques in patients with diabetes mellitus was much higher than that in non-diabetic patients. The presence of attenuated plaque detected in grayscale intravascular ultrasonography was associated with high HbA1C levels in diabetic patients. Diabetes mellitus may cause cardiovascular vulnerability by changing the plaque morphology.

The role of intravascular ultrasound in percutaneous coronary intervention of complex coronary lesions

Intravascular ultrasound (IVUS) is a catheter-based coronary imaging technique. It utilises the emission & subsequent detection of reflected high frequency (30-60 MHz) sound waves to create high resolution, cross-sectional images of the coronary artery. IVUS has been the cornerstone of intracoronary imaging for more than two decades. When compared to the invasive coronary angiogram which studies only the silhouette of the contrast-filled artery lumen, IVUS also crucially images the vessel wall. Because of this capability, IVUS has greatly facilitated understanding of the coronary atherosclerosis process. Such insights from IVUS reveal how commonly and extensively plain angiography underestimates the true extent of coronary plaque, the characteristics of plaques prone to rupture and cause acute coronary syndromes (lipid rich, thin cap atheroma), and a realisation of the widespread occurrence of vessel remodelling in response to atherosclerosis. Similarly, IVUS has historically provided salutary mechanistic insights that have guided many of the incremental advances in the techniques of percutaneous coronary intervention (PCI). Examples include mechanisms of in-stent restenosis, and the importance of high-pressure post-dilatation of stents to ensure adequate stent apposition and thereby reduce the occurrence of stent thrombosis. IVUS also greatly facilitates the choice of correct diameter and length of stent to implant. Overall, a compelling body of evidence indicates that use of intravascular ultrasound in PCI helps to achieve optimal technical results and to mitigate the risk of adverse cardiac events. In this review, the role of intravascular ultrasound as an adjunct to PCI in complex coronary lesions is explored. The complex coronary situations discussed are the left main stem, ostial stenoses, bifurcation stenoses, thrombotic lesions, the chronically occluded coronary artery, and calcified coronary artery disease. By thorough review of the available evidence, we establish that the advantages of IVUS guidance are particularly evident in each of these complex CAD subsets. In particular, some consider the use of IVUS to be almost mandatory in left main PCI. A comparison with other intracoronary imaging techniques is also explored.

Characteristics of culprit lesions in young patients with metabolic syndrome and classic cardiovascular risk factors

The association between cardiovascular risk factors (CVRFs) and characteristics of coronary plaque in young patients has remained to be fully elucidated. Therefore, the present study sought to determine the association between CVRFs and phenotypes of culprit coronary plaques revealed by optical coherence tomography (OCT) in young patients with stable coronary heart disease (CHD) and acute coronary syndrome (ACS). OCT imaging pullback was performed at corresponding sites on 123 lesions in 123 young patients (age, 36±7 years), including those with stable CHD and ACS. Patients with analyzable OCT images were classified as having thin-cap fibroatheromas (TCFAs), plaque rupture, macrophage accumulation, calcified nodule, vasa vasorum, cholesterol crystal and erosion. TCFAs were more prevalent in patients with metabolic syndrome (MetS) than in those without MetS (P=0.020). Plaque rupture was more common in smokers than in non-smokers (P=0.002). Multivariate analysis indicated that MetS was independently associated with TCFAs (P=0.041) and smoking was independently associated with plaque rupture (P=0.006). Young patients with MetS were demonstrated to have more extensive TCFAs and young smokers had a higher prevalence of culprit plaque rupture.

Culprit Lesion Characteristics in Young Patients with Hyperhomocysteinemia

Background

The relationships between culprit coronary plaque characteristics and hyperhomocysteinemia (HHcy) are not fully understood in young patients. In this study we investigated the relationship between culprit atherosclerotic plaque phenotype assessed by optical coherence tomography (OCT) and hyperhomocysteinemia (HHcy) in young patients.

Material/Methods

We investigated the OCT imaging and HHcy of 123 lesions in 123 young patients (≤45 years of age). According to OCT images, culprit lesions were classified as thin-cap fiber atheroma (TCFA), thrombus, and other. The 123 patients were grouped as: HHcy group (53 cases, HHcy ≥15.5 μmol/l) and control group (70 cases, HHcy <15.5 μmol/l).

Results

Compared with the control group, the HHcy group had a higher proportion of OCT-TCFA (p=0.03), OCT-vasa vasorum (p=0.013), and OCT-thrombus (p=0.012), and a larger lipid arc (p=0.002). HHcy (P=0.037) and metabolic syndrome (MetS) (P=0.016) remained independent predictors of TCFAs. HHcy (P=0.026) and smoking (P=0.005) remained independent determinants of thrombus.

Conclusions

HHcy and MetS are associated with TCFAs, and HHcy and smoking are associated with thrombus in young patients with coronary artery disease.

Imaging of coronary atherosclerosis in various susceptible groups

Coronary artery disease (CAD) is the leading cause of death and disability worldwide. Atherosclerosis, which is the primary pathophysiologic mechanism for the development of plaque leading to CAD, is a multifactorial process resulting from a complex interplay between genetic susceptibility and various risk factors such as hypertension (HT), dyslipidaemia, diabetes mellitus (DM) and smoking. In addition, influences from other disease states such as chronic kidney disease (CKD), obesity and the metabolic syndrome as well as gender and ethnic diversity also contribute to the disease process. Insights from pathological observations and advances in cellular and molecular biology have helped us understand the process of plaque formation, progression and rupture leading to events. Several intravascular imaging techniques such as intravascular ultrasound (IVUS), Virtual histology IVUS (VH-IVUS) and optical coherence tomography (OCT) allow in vivo assessment of plaque burden, plaque morphology and response to therapy. In addition, non invasive assessment using coronary artery calcium (CAC) score allows risk stratification and plaque burden assessment whilst computed tomography coronary angiography (CTCA) allows evaluation of luminal stenosis, plaque characterisation and quantification. This review aims to summarise the results of invasive and non-invasive imaging studies of coronary atherosclerosis seen in various high-risk populations including DM, metabolic syndrome, obesity, CKD and, gender differences and ethnicity. Understanding the phenotype of plaques in various susceptible groups may allow potential development of personalised therapies.

Relation between fractional flow reserve value of coronary lesions with deferred revascularization and cardiovascular outcomes in non-diabetic and diabetic patients

BACKGROUND

FFR of deferred PCI lesions can predict future cardiovascular events. However, the prognostic utility of FFR remains unclear in diabetic patients in view of the potential impact of the diffuse nature of vascular disease process. We aimed to study the relation between fractional flow reserve (FFR) values and long-term outcomes of diabetic and non-diabetic patients with deferred percutaneous coronary intervention (PCI).

METHODS

Patients with FFR assessment and deferred PCI (n=630) were enrolled and stratified according to diabetes mellitus (DM) status and FFR values. Patients were followed over a median of 39months. Cox proportional hazard regression models were used to analyze the association between clinical endpoints and clinical factors such as DM and FFR.

RESULTS

In non-diabetics (n=450), higher FFR values were associated with less cardiovascular events (hazard ratio (HR) for death and myocardial infarction (MI) [95% confidence interval (CI)], 0.61[0.44 to 0.86] per 0.1 increase in FFR, p=0.007; HR for revascularization [95%CI], 0.66[0.49 to 0.9] per 0.1 increase in FFR, p=0.006). In diabetics (n=180), there was no difference in death and MI across the range of FFR values. Among those patients with an FFR >0.85, diabetics had a more than two-fold higher risk of death and MI than non-diabetics (HR [95% CI], 2.20 [1.19 to 4.01], p=0.015).

CONCLUSION

Among non-diabetic patients with deferred PCI, a higher FFR was associated with lower rates of death, MI and revascularization. On the contrary in diabetic patients with deferred revascularization, FFR was not able to differentiate the risk of cardiovascular events.

Relationships between components of metabolic syndrome and coronary intravascular ultrasound atherosclerosis measures in women without obstructive coronary artery disease: the NHLBI-Sponsored Women's Ischemia Syndrome Evaluation Study

OBJECTIVE

In women, metabolic syndrome (MetS) is associated with higher risk of ischemic heart disease-related adverse outcomes versus individual components. We examined the relationship of MetS to subclinical coronary atherosclerosis.

METHODS

Women (n = 100) undergoing coronary angiography for suspected ischemia but without obstructive coronary artery disease (CAD) underwent intravascular ultrasound (IVUS) of a segment of the left coronary artery. A core lab, masked to other findings, assessed IVUS measures and normalized volume measures to pull-back length. MetS [defined using ATPIII criteria (fasting glucose ≥ 100 mg/dl per revised NCEP guideline)] and its components were entered into multiple regression models to assess associations with IVUS measures.

RESULTS

Detailed IVUS measurements were available in 87 women. Mean age was 54 ± 10 years, 36% had MetS, and 78% had atheroma. Comparing women with MetS versus without MetS, significant differences were observed for seven IVUS atherosclerosis measures, but were not significant after adjusting for the MetS components. Systolic blood pressure and waist circumference components remained independently positively associated with the IVUS measures after adjusting for age, diabetes, CAD family history, dyslipidemia, smoking, and hormone replacement.

CONCLUSION

In women with signs and symptoms of ischemia and no obstructive CAD, MetS is associated with coronary atherosclerosis presence and severity. However, these associations appear largely driven by components of waist circumference and systolic blood pressure versus MetS cluster. This supports the concept that MetS is a convenient clustering of risk factors rather than an independent risk predictor, and emphasizes that the critical factors for coronary atherosclerosis are potentially modifiable.

Compensatory Enlargement of Ossabaw Miniature Swine Coronary Arteries in Diffuse Atherosclerosis

Studies in human and non-human primates have confirmed the compensatory enlargement or positive remodeling (Glagov phenomenon) of coronary vessels in the presence of focal stenosis. To our knowledge, this is the first study to document arterial enlargement in a metabolic syndrome animal model with diffuse coronary artery disease (DCAD) in the absence of severe focal stenosis. Two different groups of Ossabaw miniature pigs were fed a high fat atherogenic diet for 4 months (Group I) and 12 months (Group II), respectively. Group I (6 pigs) underwent contrast enhanced computed tomographic angiography (CCTA) and intravascular ultrasound (IVUS) at baseline and after 4 months of high fat diet, whereas Group II (7 pigs) underwent only IVUS at 12 months of high fat diet. IVUS measurements of the left anterior descending (LAD), left circumflex (LCX) and right coronary (RCA) arteries in Group I showed an average increase in their lumen cross-sectional areas (CSA) of 25.8%, 11.4%, and 43.4%, respectively, as compared to baseline. The lumen CSA values of LAD in Group II were found to be between the baseline and 4 month values in Group I. IVUS and CCTA measurements showed a similar trend and positive correlation. Fractional flow reserve (FFR) was 0.91 ± 0.07 at baseline and 0.93 ± 0.05 at 4 months with only 2.2%, 1.6% and 1% stenosis in the LAD, LCX and RCA, respectively. The relation between percent stenosis and lumen CSA shows a classical Glagov phenomenon in this animal model of DCAD.

Impact of coronary lesion complexity on drug-eluting stent outcomes in patients with and without diabetes mellitus: analysis from 18 pooled randomized trials

OBJECTIVES

The aim of this study was to investigate whether baseline lesion complexity affects drug-eluting stent (DES) outcomes according to diabetic status.

BACKGROUND

Previous studies have reported conflicting results regarding DES safety and efficacy in patients with and without diabetes mellitus (DM).

METHODS

Patient-level data from 18 prospective randomized trials were pooled. DES treatment outcomes in patients with versus without DM were analyzed in 2 propensity score-matched groups further stratified according to lesion complexity (American College of Cardiology and American Heart Association class A/B1 vs. B2/C). Remaining baseline differences were adjusted for by multivariate analysis.

RESULTS

DM was present in 3,467 of 18,441 patients (18.8%). DM was a predictor of 1-year repeat revascularization (target lesion revascularization: hazard ratio: 1.34; 95% confidence interval: 1.05 to 1.70; target vessel revascularization: hazard ratio: 1.40; 95% confidence interval: 1.15 to 1.72) and cardiac death or myocardial infarction (hazard ratio: 1.40; 95% confidence interval: 1.09 to 1.81). Rates of target lesion and target vessel revascularization were significantly higher in patients with versus those without DM with type B2/C lesions (8.0% vs. 4.5% and 10.6% vs. 5.9%, respectively, p < 0.0001 for both), but not in patients with only type A/B1 lesions (4.6% vs. 4.8%, p = 0.87, and 7.4% vs. 6.8%, p = 0.47, respectively), with a significant interaction between DM and lesion type observed for both endpoints (p = 0.01 and p = 0.02, respectively). No interaction was observed for death or myocardial infarction (p = 0.28).

CONCLUSIONS

In the DES era, patients with DM remain at increased risk for cardiac death or myocardial infarction. However, DM is a risk factor for repeat revascularization only in those patients with complex lesions; patients with DM and noncomplex lesions have similar rates of 1-year freedom from repeat revascularization as do patients without DM.

Features of coronary plaque in patients with metabolic syndrome and diabetes mellitus assessed by 3-vessel optical coherence tomography

BACKGROUND

The pathophysiological basis for the association between metabolic syndrome (MetS) and coronary artery disease is not well understood. We sought to characterize coronary plaques in patients with MetS by using optical coherence tomography.

METHODS AND RESULTS

We identified 451 coronary plaques from 171 subjects who underwent optical coherence tomographic imaging in 3 coronary arteries. Subjects were divided into 3 groups: diabetes mellitus (DM, n=77), MetS (n=35), and a control group (C group, n=59) without DM or MetS. Optical coherence tomographic analysis included the presence of lipid-rich plaque, maximum lipid arc, lipid-core length, lipid index (LI), fibrous cap thickness, and thin-cap fibroatheroma. We defined LI as mean lipid arc multiplied by lipid-core length. Lipid-core length and LI were significantly greater in DM and MetS than in C group (lipid-core length: 7.7 ± 4.0 and 7.0 ± 3.8 versus 5.5 ± 2.4 mm; P<0.001 and P=0.012, and LI: 1164 ± 716 and 1086 ± 693 versus 796 ± 417 mm; P<0.001 and P=0.008). Maximum lipid arc was significantly greater in DM than in C group, whereas no significant difference was observed between MetS and C group (196 ± 45°, 187 ± 42° versus 176 ± 52°; P=0.002 and P=0.182). Fibrous cap thickness and thin-cap fibroatheroma showed no significant difference among the 3 groups. In multivariate analysis, DM and MetS were independently associated with LI, whereas only acute coronary syndrome was the independent predictor for thin-cap fibroatheroma.

CONCLUSIONS

Compared with control subjects, coronary plaques in MetS contain larger lipid. However, the MetS criteria used in this study could not distinguish the vulnerable features such as thin-cap fibroatheroma, suggesting the necessity of complementary information to identify patients at high risk for cardiovascular events.

Comparison of nonculprit coronary plaque characteristics between patients with and without diabetes: a 3-vessel optical coherence tomography study

OBJECTIVES

The aim of the present study was to compare the characteristics of nonculprit coronary plaques between diabetes mellitus (DM) and non-DM patients using 3-vessel optical coherence tomography (OCT) imaging.

BACKGROUND

DM patients have a higher recurrent cardiovascular event rate.

METHODS

Patients who had undergone 3-vessel OCT imaging were identified from the Massachusetts General Hospital OCT Registry. Characteristics of nonculprit plaques were compared between DM and non-DM patients.

RESULTS

A total of 230 nonculprit plaques were identified in 98 patients. Compared with non-DM patients, DM patients had a larger lipid index (LI) (averaged lipid arc × lipid length; 778.6 ± 596.1 vs. 1358.3 ± 939.2, p < 0.001) and higher prevalence of calcification (48.4% vs. 72.2%, p = 0.034) and thrombus (0% vs. 8.3%, p = 0.047). DM patients were divided into 2 groups based on glycated hemoglobin (A(1C)) levels of ≤7.9% and ≥8.0%. LI was significantly correlated with diabetic status (778.6 ± 596.1 [non-DM] vs. 1,171.5 ± 708.1 [A(1C) ≤7.9%] vs. 1,638.5 ± 1,173.8 [A(1C) ≥8%], p value for linear trend = 0.005), and fibrous cap thickness was inversely correlated with the A(1C) level (99.4 ± 46.7 μm [non-DM] vs. 91.7 ± 29.6 μm [A(1C) ≤7.9%] vs. 72.9 ± 22.7 μm [A(1C) ≥8%], p value for linear trend = 0.014). Patients with A(1C) ≥8% also had the highest prevalence of thin-cap fibroatheroma (TCFA) and macrophage infiltration.

CONCLUSIONS

Compared with non-DM patients, DM patients have a larger LI and a higher prevalence of calcification and thrombus. The LI was larger and TCFA and macrophage infiltration were frequent in patients with A(1C) ≥8%.

Coronary aspirate TNFα reflects saphenous vein bypass graft restenosis risk in diabetic patients

BACKGROUND

Patients with diabetes mellitus (DM) have an increased risk for periprocedural complications and adverse cardiac events after percutaneous coronary intervention. We addressed the potential for coronary microvascular obstruction and restenosis in patients with and without DM undergoing stenting for saphenous vein bypass graft (SVG) stenosis under protection with a distal occlusion/aspiration device.

METHODS

SVG plaque volume and composition were analyzed using intravascular ultrasound before stent implantation. Percent diameter stenosis was determined from quantitative coronary angiography before, immediately after and 6 months after stent implantation. Coronary aspirate was retrieved during stent implantation and divided into particulate debris and plasma. Total calcium, several vasoconstrictors, and tumor necrosis factor (TNF)α in particulate debris and coronary aspirate plasma were determined.

RESULTS

Patients with and without DM had similar plaque volume, but larger necrotic core and greater particulate debris release in patients with than without DM (20.3±2.7 vs. 12.7±2.6% and 143.9±19.3 vs. 75.1±10.4 mg, P<0.05). The TNFα concentration in particulate debris and coronary aspirate plasma was higher in patients with than without DM (15.9±6.6 vs. 5.1±2.4 pmol/mg and 2.2±0.7 vs. 1.1±0.2 pmol/L, P<0.05), whereas total calcium and vasoconstrictors were not different. Patients with DM had a greater percent diameter stenosis 6 months after stent implantation than those without DM (22.17±5.22 vs. 6.34±1.11%, P<0.05). The increase in TNFα immediately after stent implantation correlated with restenosis 6 months later (r=0.69, P<0.05).

CONCLUSION

In diabetics, particulate debris and coronary aspirate plasma contained more TNFα, which might reflect the activity of the underlying atherosclerotic process.

TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov/ct2/results?term=NCT01430884; unique identifier: NCT01430884.

Comparison of frequency of periprocedural myocardial infarction in patients with and without diabetes mellitus to those with previously unknown but elevated glycated hemoglobin levels (from the TWENTE Trial)

In patients without a history of diabetes mellitus, increased levels of glycated hemoglobin (HbA1c) are associated with higher cardiovascular risk. The relation between undetected diabetes and clinical outcome after percutaneous coronary intervention is unknown. To investigate whether these patients may have an increased risk of periprocedural myocardial infarction (PMI), the most frequent adverse event after percutaneous coronary intervention, we assessed patients of the TWENTE trial (a randomized, controlled, second-generation drug-eluting stent trial) in whom HbA1c data were available. Patients were classified as known diabetics or patients without a history of diabetes who were subdivided into undetected diabetics (HbA1c ≥6.5%) and nondiabetics (HbA1c <6.5%). Systematic measurement of cardiac biomarkers and electrocardiographic assessment were performed. One-year clinical outcome was also compared. Of 626 patients, 44 (7%) were undetected diabetics, 181 (29%) were known diabetics, and 401 (64%) were nondiabetics. In undetected diabetics the PMI rate was higher than in nondiabetics (13.6% vs 3.7%, p = 0.01) and known diabetics (13.6% vs 6.1%, p = 0.11). Multivariate analysis adjusting for covariates confirmed a significantly higher PMI risk in undetected diabetics compared to nondiabetics (odds ratio 6.13, 95% confidence interval 2.07 to 18.13, p = 0.001) and known diabetics (odds ratio 3.73, 95% confidence interval 1.17 to 11.89, p = 0.03). After 1 year, target vessel MI rate was significantly higher in undetected diabetics (p = 0.02) than in nondiabetics, which was related mainly to differences in PMI. Target vessel failure was numerically larger in unknown diabetics than in nondiabetics, but this difference did not reach statistical significance (13.6% vs 8.0%, p = 0.25). In conclusion, undetected diabetics were shown to have an increased risk of PMI.