Intravascular ultrasonic analysis of plaque characteristics associated with coronary artery remodeling

The role of sRAGE in cardiovascular diseases

Advanced glycation end products (AGEs), by-products of glucose metabolism, have been linked to the emergence of cardiovascular disorders (CVD). AGEs can cause tissue damage in four different ways: (1) by altering protein function, (2) by crosslinking proteins, which makes tissue stiffer, (3) by causing the generation of free radicals, and (4) by activating an inflammatory response after binding particular AGE receptors, such as the receptor for advanced glycation end products (RAGE). It is suggested that the soluble form of RAGE (sRAGE) blocks ligand-mediated pro-inflammatory and oxidant activities by serving as a decoy. Therefore, several studies have investigated the possible anti-inflammatory and anti-oxidant characteristics of sRAGE, which may help lower the risk of CVD. According to the results of various studies, the relationship between circulating sRAGE, cRAGE, and esRAGE and CVD is inconsistent. To establish the potential function of sRAGE as a therapeutic target in the treatment of cardiovascular illnesses, additional studies are required to better understand the relationship between sRAGE and CVD. In this review, we explored the potential function of sRAGE in different CVD, highlighting unanswered concerns and outlining the possibilities for further investigation.

Comparison of cardiac CT angiography coronary artery dimensions and ethnicity in Trinidad: the CADET pilot study

Background

This study aimed to determine if there were any significant differences in coronary artery (CA) dimensions at prespecified segments during cardiac CT angiography (CCTA) compared with ethnicity at an academic tertiary medical centre in Trinidad and Tobago.

Methods

Patients (n=170) who underwent CCTA from July 2016 to June 2021 at the Eric Williams Medical Sciences Complex were selected based on predefined selection criteria. The size of the left main and proximal, mid and distal diameters of the left anterior descending, left circumflex and right coronary artery (RCA) were measured using quantitative coronary angiography, syngo.CT Coronary Analysis (Siemens Healthineers AG, Erlangen, Germany). Routine medical history, cardiovascular medications and anthropometric data were also recorded. Comparisons were performed using an independent sample t-test and analysis of variance for continuous variables.

Results

One hundred and seventy participants were enrolled in this study. There were no statistically significant associations between gender and CA dimensions; however, there were significant associations between South Asian and Caribbean black ethnicities for almost all CA dimensions except for the distal RCA segment. These findings were replicated when the analysis was adjusted for body surface area with the addition of the mid-RCA segment, which was bordering near-significance (p value 0.051).

Conclusions

Significantly smaller CA dimensions were observed in South Asian patients compared with Caribbean black patients undergoing CCTA. This pilot study could be clinically significant for Trinidadian patients at risk of developing coronary artery disease.

Trial registration number

NCT04774861.

Increased glycated albumin and decreased esRAGE levels in serum are related to negative coronary artery remodeling in patients with type 2 diabetes: an Intravascular ultrasound study

BACKGROUND

Negative coronary artery remodeling is frequent in patients with diabetes, but its mechanism remains unclear. We here evaluated the association of serum levels of glycated albumin (GA) and endogenous secretory receptor for advanced glycation end products (esRAGE) with coronary artery remodeling in type 2 diabetic patients.

METHODS

Serum levels of GA and esRAGE were measured and intravascular ultrasound was performed in 136 consecutive diabetic patients with 143 coronary intermediate lesions. The remodeling index (RI) was calculated as the ratio between external elastic membrane (EEM) area at the lesion site and EEM area at the reference segment. Negative remodeling (NR) was defined as an RI < 0.95 and intermediate or positive remodeling as an RI ≥ 0.95.

RESULTS

Mean plaque burden at the lesion site was 70.96 ± 9.98%, and RI was 0.96 ± 0.18. Negative coronary arterial remodeling existed in 81 (56.6%) lesions. RI correlated closely with serum esRAGE level (r = 0.236, P = 0.005) and was inversely related to serum GA level (r = - 0.240, P = 0.004) and plasma low-density lipoprotein cholesterol (LDL-C) (r = - 0.206, P = 0.014) and total cholesterol levels (r = - 0.183, P = 0.028). Generalized estimating equations logistic regression analysis identified esRAGE (OR 0.037; 95% CI 0.012-0.564, P = 0.021), GA (OR 1.093; 95% CI 1.013-1.179, P = 0.018) and LDL-C (OR 1.479; 95% CI 1.072-2.835, P = 0.023) as independent predictors for negative remodeling.

CONCLUSIONS

In diabetic patients, negative coronary artery remodeling is associated with increased GA and decreased esRAGE levels in serum.

Pathology of Human Coronary and Carotid Artery Atherosclerosis and Vascular Calcification in Diabetes Mellitus

The continuing increase in the prevalence of diabetes mellitus in the general population is predicted to result in a higher incidence of cardiovascular disease. Although the mechanisms of diabetes mellitus-associated progression of atherosclerosis are not fully understood, at clinical and pathological levels, there is an appreciation of increased disease burden and higher levels of arterial calcification in these subjects. Plaques within the coronary arteries of patients with diabetes mellitus generally exhibit larger necrotic cores and significantly greater inflammation consisting mainly of macrophages and T lymphocytes relative to patients without diabetes mellitus. Moreover, there is a higher incidence of healed plaque ruptures and positive remodeling in hearts from subjects with type 1 diabetes mellitus and type 2 diabetes mellitus, suggesting a more active atherogenic process. Lesion calcification in the coronary, carotid, and other arterial beds is also more extensive. Although the role of coronary artery calcification in identifying cardiovascular disease and predicting its outcome is undeniable, our understanding of how key hormonal and physiological alterations associated with diabetes mellitus such as insulin resistance and hyperglycemia influence the process of vascular calcification continues to grow. Important drivers of atherosclerotic calcification in diabetes mellitus include oxidative stress, endothelial dysfunction, alterations in mineral metabolism, increased inflammatory cytokine production, and release of osteoprogenitor cells from the marrow into the circulation. Our review will focus on the pathophysiology of type 1 diabetes mellitus- and type 2 diabetes mellitus-associated vascular disease with particular focus on coronary and carotid atherosclerotic calcification.

Adaptive-Outward and Maladaptive-Inward Arterial Remodeling Measured by Intravascular Ultrasound in Hyperhomocysteinemia and Diabetes

Background: Coronary artery remodeling implies structural changes in the vessel wall in response to various pathophysiologic conditions. However, the classification of remodeling is unclear. We hypothesized that the adaptive, positive-outward remodeling is a reactive and compensatory response to the stress. The maladaptive negative-inward constrictive remodeling is a passive atherosclerotic condition in which the vessel becomes stiffer.

Methods: Patients with atherosclerotic lesions underwent intravascular ultrasound (IVUS) scans. The size of the vessels distal to and proximal to plaques were analyzed by IVUS. Diabetes was created in mice by an intraperitoneal injection of alloxan (65 mg/kg). To reduce remodeling, mice received ciglitazone, an agonist of peroxisome proliferators activated receptor-g (PPARg) in drinking water. After 8 weeks, atherosclerotic vessels were analyzed for collagen and elastin.

Results: IVUS data suggest an adaptive coronary arterial remodeling was a positive compensatory response to various pathologic stimuli; for example, with the deposition of atherosclerotic plaque, coronary arterial segments enlarged to maintain luminal area. This phenomenon was commonly observed during the initial phases of the development of atherosclerosis. However, negative coronary artery remodeling, or a decrease in vessel area with the formation of atherosclerotic plaque, was maladaptive and was associated with smoking, hypertension, hyperhomocysteinemia, diabetes mellitus, and also after percutaneous coronary interventions (restenosis). In diabetic mice, there was increased collagen and decreased elastin contents; however, treatment with ciglitazone ameliorated the decrease in elastin contents.

Conclusion: Global enlargement of the coronary vascular tree occurs during pressure and volume overload associated with ventricular hypertrophic states such as athletic conditioning, hypertensive heart disease, and dilated cardiomyopathy. On the other hand, maladaptive coronary arterial remodeling occurs in patients with severe deconditioning, diabetes mellitus, after coronary artery bypass surgery, and in some instances, postintervention.

Age-related effects of smoking on coronary artery disease assessed by gray scale and virtual histology intravascular ultrasound

Although smoking is a risk factor for coronary atherosclerosis, the age-related impact on lesion morphology has not been studied. The aim of this study was to assess the age-related impact of smoking on the extent of atherosclerosis and arterial remodeling. In Providing Regional Observations to Study Predictors of Events in the Coronary Tree, 687 patients with acute coronary syndrome underwent 3-vessel gray scale and virtual histology intravascular ultrasound imaging of 3,185 nonculprit lesions. In 207 patients ≤65 years, current (smoking within 1 month) and former (no smoking for >1 month) smokers showed significantly smaller normalized volumes of external elastic membrane (EEM), lumen, and P + M (plaque + media) compared with nonsmokers. At the minimal lumen area site, current and former smokers had significantly smaller EEM, lumen, and P + M areas than nonsmokers. Conversely, in 480 patients >65 years, current smokers had greater normalized P + M volumes than nonsmokers with no difference in normalized EEM or lumen volumes. Finally, in patients >65 years (but not in patients ≤65 years), current smokers showed more plaque ruptures (4.7% vs 1.8%, p = 0.05) and echolucent plaques (8.3% vs 3.9%, p = 0.05) compared with nonsmokers. On multivariable analysis, a history of smoking (combining current and former smoking) predicted smaller normalized EEM volumes compared with nonsmokers ≤65 years. In conclusion, in patients ≤65 years, but not in patients >65 years, smoking had a vascular constrictive effect that contributed to severe luminal stenosis. Conversely, smokers >65 years had more plaque with greater plaque instability.

Coronary plaque characteristics that indicate distal embolization during percutaneous coronary intervention in patients with stable angina-virtual histology intravascular ultrasound study

Distal embolization (DE) is a serious complication of percutaneous coronary intervention (PCI) in patients with stable angina. The purpose of this study was to evaluate the coronary plaque characteristics that indicate DE during PCI in patients with stable angina using virtual histology intravascular ultrasound (VH-IVUS). Three hundred and sixty-four consecutive stable angina patients who underwent PCI were enrolled in this study. The patients were divided into two groups as follows: patients exhibiting DE (DE group, n = 10) and patients without DE (non-DE group, n = 354). Coronary plaque compositions were assessed by VH-IVUS. The fibro-fatty (FF) ratio (28 ± 17 vs. 11 ± 9 %, p < 0.0001) was higher in the DE group compared with the non-DE group. The best cut-off value of FF ratio for prediction of DE was 20 %, with a sensitivity of 0.80 and a specificity of 0.81 (odds ratio; 17.1, 95 % confidence interval 3.56-82.5, p = 0.0004). Coronary plaques with a high FF ratio may be the predictor of indicating DE in patients with stable angina during PCI.

Coronary plaque quantification and composition in asymptomatic patients with type II diabetes mellitus

OBJECTIVE

The aim of this study was to characterize the extent and morphology of coronary lesions in asymptomatic patients with type II diabetes mellitus.

METHODS

We enrolled 102 asymptomatic patients with type II diabetes mellitus and 97 patients without diabetes as controls. All individuals had no history of ischemic heart disease. They underwent multidetector computed tomography (MDCT). Plaque density and plaque volume were calculated using specific software on axial images. Arterial remodeling was evaluated with semiquantitative assessment on image reconstructions.

RESULTS

MDCT angiography revealed the presence of 124 coronary plaques in 46 patients with type II diabetes mellitus and 59 plaques in 21 controls (P<0.01). Diabetic patients had a significantly higher proportion of lesions with impaired adaptive remodeling (56.5 versus 35.6%, P<0.01), as compared with nondiabetic individuals. The volume of fibrofatty component was 0.1 cm (0.01-0.72) in diabetic patients and 0.08 cm (0.01-0.33) in controls (P=0.14). The calcium volume was 0.082 cm (0-0.558) in diabetic patients and 0.12 cm (0-0.669) in controls (P=0.21). Plaques with fibrofatty components had a significantly higher density in the diabetic cohort (58.76  ±  9.55  Hounsfield Units), as compared with the control group (47.31  ±  5.42 Hounsfield Units, P<0.001). Plaque density correlated with the duration of type II diabetes mellitus (r=0.37, P=0.044), but was independent of age, sex, hypertension and metabolic profile. In the control group, plaque density was independent of any covariate.

CONCLUSION

Coronary plaques in type II diabetes mellitus show a tendency to develop impaired adaptive remodeling and to have a higher tissue density.

Effect of hypertension on coronary remodeling patterns in angiographically normal or minimally atherosclerotic coronary arteries: an intravascular ultrasound study

Whether there is any particular role of hypertension in remodeling process has not been completely understood yet. The aim of this study was to assess the association between hypertension and remodeling patterns in normal or minimally atherosclerotic coronary arteries. Seventy-nine patients who were free of significant coronary atherosclerosis were divided into two groups according to the absence (n = 39) or presence (n = 40) of hypertension; and standard intravascular ultrasound examination was performed in 145 segments. To determine the remodeling pattern in early atherosclerotic process, patients were also analyzed according to the level of plaque burden at the lesion site after the analysis of remodeling patterns. Positive remodeling was more prevalent in the hypertensive group (52.5% vs. 12.8%; P < .001) whereas negative remodeling was more common in diabetic patients (53.6% vs. 27.4%; P = .03). Mean remodeling index was 1.04 for hypertensives and 0.96 for normotensives (P = .03). There were no correlations between remodeling patterns and other risk factors such as age, family history, and hypercholesterolemia. Early atherosclerotic lesions (< 30%) exhibited more negative remodeling characteristics while intermediate pattern was observed more frequently in patients with high plaque burden (P = .006 and .02, respectively). Positive remodeling showed no association in this context (P = .07). This study demonstrated that minimal atherosclerotic lesions in hypertensives had a tendency for compensatory arterial enlargement. Positive remodeling may result from local adaptive processes within vessel wall or hemodynamic effects of blood pressure itself.

Characterization of hyperintense plaque with noncontrast T(1)-weighted cardiac magnetic resonance coronary plaque imaging: comparison with multislice computed tomography and intravascular ultrasound

OBJECTIVES

This study sought to characterize coronary hyperintense plaques (HIP) using noncontrast T(1)-weighted imaging (T1WI) in cardiac magnetic resonance, which was then compared with multislice computed tomography and intravascular ultrasound.

BACKGROUND

Carotid plaque components such as intraplaque hemorrhages and/or lipid-rich necrotic cores can be detected as HIP by noncontrast T1WI. Although coronary HIPs have been successfully detected using this technique, the properties of hyperintense signals in coronary plaques have not yet been systematically evaluated.

METHODS

Thirty-eight lesions from 37 patients with angina pectoris who demonstrated >70% coronary stenosis on multislice computed tomography were evaluated by noncontrast T1WI using a 1.5-T magnetic resonance imager, and 25 lesions were evaluated by intravascular ultrasound. Signal intensity of coronary plaque to cardiac muscle ratio >1.0 was defined as HIP. We divided 25 lesions into the 2 groups, according to the presence or absence of HIP: HIP (n = 18) and non-HIP (n = 7) groups.

RESULTS

In comparison with the non-HIP group, the HIP group demonstrated significantly higher coronary plaque to cardiac muscle ratio (1.7 +/- 0.7 vs. 0.9 +/- 0.1, p < 0.01), higher frequency of positive remodeling as observed by both multislice computed tomography (89% vs. 0%, p<0.0001) and intravascular ultrasound (94% vs. 14%, p < 0.001) and ultrasound attenuation (100% vs. 14.3%, p < 0.0001). The frequency of spotty calcification tended to be higher in HIP (89% vs. 50%, p = 0.079). The HIP group also exhibited a significantly lower computed tomography density (-23.2 +/- 20.7 Hounsfield units [HU] vs. 9.6 +/- 20.5 HU, p < 0.01). In addition, the incidence of transient slow-flow phenomena was significantly higher in the HIP group than in the non-HIP group (83% vs. 14%, p < 0.01).

CONCLUSIONS

The typical HIP case was associated with ultrasound attenuation, positive remodeling, remarkably low computed tomography density, and a high incidence of slow-flow phenomena. Noncontrast T1WI in cardiac magnetic resonance imaging may be useful for the assessment of coronary plaque characterization in patients with coronary artery disease.

Vessel shrinkage as a sign of atherosclerosis progression in type 2 diabetes: a serial intravascular ultrasound analysis

OBJECTIVE

The aim of this study was to determine the natural history of vascular remodeling of atherosclerotic plaques in patients with type 2 diabetes and the predictors of vessel shrinkage.

RESEARCH DESIGN AND METHODS

In this serial intracoronary ultrasound (IVUS) study, 237 coronary segments from 45 patients enrolled in the DIABETES I, II, and III trials were included. Quantitative volumetric IVUS analyses (motorized pullbacks at 0.5 mm/s) were performed in the same coronary segment after the index procedure and at the 9-month follow-up. Nontreated mild lesions (angiographic stenosis <25%) with > or =0.5 mm plaque thickening and length of > or =5 mm assessed by IVUS were included. Vessel shrinkage was defined as a Deltaexternal elastic membrane area/Deltaplaque area < 0. Statistical adjustment by multiple segments and multiple lesions per patient was performed.

RESULTS

Vessel shrinkage was identified in 37.1% of segments and was associated with a significant decrease in lumen area at 9 months (vessel shrinkage, 10 +/- 4 mm(2) vs. non-vessel shrinkage, 11 +/- 4 mm(2); P = 0.04). Independent predictors of vessel shrinkage were insulin requirements (odds ratio 4.6 [95% CI 1.40-15.10]; P = 0.01), glycated hemoglobin (1.5 [1.05-2.10]; P = 0.02), apolipoprotein B (0.96 [0.94-0.98]; P < 0.001), hypertension (3.7 [1.40-10.30]; P = 0.009), number of diseased vessels (5.6 [2.50-12.50]; P < 0.001), and prior revascularization (17.5 [6.50-46.90]; P < 0.001).

CONCLUSIONS

This serial IVUS study suggests that progression of coronary artery disease in patients with type 2 diabetes may be mainly attributed to vessel shrinkage. Besides, vessel shrinkage is influenced by insulin requirements and metabolic control and is associated with more advanced coronary atherosclerosis.

Morphological characteristics of coronary atherosclerosis in diabetes mellitus

The incidence of diabetes is increasing in the general population because of increasing obesity, and is likely to result in a higher incidence of coronary artery disease. It was recently reported that diabetics (types I and II) dying suddenly from coronary artery disease have greater macrophage and T lymphocyte infiltration in atherosclerotic plaques, as well as larger necrotic cores compared with nondiabetics. The inflammatory cell infiltrates showed human leukocyte antigen-DR expression, which was greater in diabetics. The receptors for advanced glycosylation end-products expression, demonstrated by immunohistochemistry, was greater in diabetics than in nondiabetics in macrophages, smooth muscle cells and endothelial cells, and was associated with apoptosis of macrophages and smooth muscle cells, but not of endothelial cells. There is also a higher incidence of healed plaque ruptures and healed myocardial infarct in type II diabetics. Plaque burden is higher in diabetics than in nondiabetics; however, distal plaque burden was only significantly different in type II diabetics compared with nondiabetics. There was greater positive remodelling in diabetic coronary arteries than in nondiabetic ones, which correlated with the per cent necrotic core. Further studies are needed to better understand the mechanisms that govern greater inflammation and plaque burden in diabetics.

Effects of percutaneous transluminal angioplasty and endovascular brachytherapy on vascular remodeling of human femoropopliteal artery: 2 years follow-up by noninvasive magnetic resonance imaging

OBJECTIVES

We aimed to assess in vivo the long-term effects of percutaneous transluminal angioplasty (PTA) and endovascular brachytherapy (EVBT) on vessel wall by serial MRI.

METHODS

Twenty patients with symptomatic stenosis of the femoropopliteal artery were randomly assigned to PTA (n=10) or PTA+EVBT (n=10, 14Gy by gamma-source). High-resolution MRI was performed prior, at 24-hours, 3-months, and 24-months after intervention. MRI data were analyzed by an independent, blinded observer.

RESULTS

The effects of both procedures on vessel wall at 24-hours and 3-months have been reported. Despite similar percent decrease in lumen area between 3- and 24-months in both groups (-8% for PTA and -11% for PTA+EVBT), at 24-months lumen area gain compared to baseline was +30% in PTA versus +82% in PTA+EVBT (p<0.05). Total vessel area, which was increased at 24-hours and 3-months, returned to pre-treatment value in both groups.

CONCLUSIONS

We demonstrated non-invasively that restenosis and inward remodeling after PTA are delayed by EVBT. At 24-months, patients treated with brachytherapy have larger lumen than those treated with PTA alone. The decrease in luminal and total vessel area between 3- and 24-months after EVBT indicates that the restenotic and remodeling process is not abolished but delayed with this therapy.

Heterogeneity of atherosclerotic plaque characteristics in human coronary artery disease: A three-dimensional intravascular ultrasound study

OBJECTIVES

The objective of this study was to describe the intraplaque variability of coronary atherosclerosis in humans.

BACKGROUND

Atherosclerosis is a heterogeneous process. The degree and patterns of intraplaque heterogeneity are not well described. This study uses 3D intravascular ultrasound (IVUS) to examine variability in individual atherosclerotic plaques in human coronary arteries.

METHODS

IVUS images of 170 coronary plaques in 98 patients were evaluated. Each plaque was divided into proximal, middle, and distal sections. Quantitative and qualitative analyses were performed for each section using a dedicated 3D IVUS protocol. Intralesion heterogeneity was assessed between sections.

RESULTS

Heterogeneity in composition was observed in most plaques (89%). The pattern of remodeling was heterogeneous in 23% of lesions. External elastic membrane (EEM) areas demonstrated an average percent deviation of 28.9% +/- 15.5%. Positive remodeling was associated with longer lesions (>> median length of 12.7 mm) (P = 0.031). Soft and calcific sections had a smaller mean EEM area (P = 0.034). Calcific lesions had a smaller mean lumen area (P = 0.027) and a greater percent plaque burden (PPB) (P = 0.001). Neither the location within the vessel or within the plaque was associated with plaque morphology. Greater qualitative heterogeneity was found in patients presenting with acute coronary syndrome (P < 0.001).

CONCLUSIONS

Our results demonstrate a high degree of heterogeneity in composition and morphological features within individual atherosclerotic plaques in human coronary arteries. Intraplaque heterogeneity represents a challenge for imaging protocols correlating plaque features with cardiovascular events and for the development of future therapeutic options.

Preintervention arterial remodeling as a predictor of intimal hyperplasia after intracoronary stenting: a serial intravascular ultrasound study

BACKGROUND

The impact of vascular remodeling pattern on intimal hyperplasia (IH) after coronary stenting is unknown.

HYPOTHESIS

The preintervention remodeling pattern of the lesion might be associated with IH after the coronary stenting procedure.

METHODS

Serial (pre-, post-stent implantation, and follow-up) intravascular ultrasound (IVUS) images were obtained in 58 patients with single-stent implantation (GFX stents in 41 and NIR in 17). The matching IVUS image slices at the preintervention lesion site were selected for serial comparisons. The remodeling index (RI) was defined as lesion/proximal reference external elastic membrane cross-sectional area (CSA) at preintervention lesion site. Adequate remodeling was defined as a RI > 0.95 and inadequate remodeling as a RI < or = 0.95. Vessel stretching, percent vessel stretching, and percent IH CSA, as well as pre- and postintervention IVUS variables were evaluated according to the remodeling pattern.

RESULTS

The percent IH CSA was 31% in adequate remodeling (n = 29, mean RI = 1.05) and 41% in inadequate remodeling (n = 29, mean RI = 0.88) (p = 0.049). Percent vessel stretching was 15% in adequate remodeling and 22% in inadequate remodeling (p = 0.007). The RI inversely correlated with percent vessel stretching (r = -0.435, p = 0.001).

CONCLUSIONS

Compared with preintervention adequate remodeling, inadequate remodeling was associated with increased percent IH CSA, which might be related with more vessel stretching.

Effect of Simvastatin on Coronary Lesion Site Remodeling: A Serial Intravascular Ultrasound Study

BACKGROUND

Direct evidence of coronary artery remodeling can be derived only from serial changes in the external elastic membrane (EEM) and plaque area. The aim of the study was to assess the effect of simvastatin on coronary remodeling in serial intravascular ultrasound (IVUS) studies.

METHODS

In 39 male patients ECG-triggered transducer pullback IVUS was performed at baseline, after 3 months on a lipid-lowering diet (control period), and after another 12 months of simvastatin 40 mg/day. The lesion site was the image slice with maximum plaque burden at 3 months.

RESULTS

Absolute changes in the EEM area correlated significantly with changes in plaque area during the control period [B = 0.966, r = 0.792 (95% CI 0.71-1.22); p < 0.001] and during simvastatin treatment [B = 0.945, r = 0.822 (95% CI 0.73-1.16); p < 0.001], but there was no significant difference in the slope (delta EEM/delta plaque) between the two time intervals. After 12 months of simvastatin, there was a significant reduction in the lesion EEM area of 4.6% (p = 0.006) and in the lesion plaque area of 5.9% (p < 0.001), but there was no change in reference measurements. As a result, the remodeling index was reduced by simvastatin from 1.01 +/- 0.12 to 0.95 +/- 0.09 (p < 0.001).

CONCLUSION

Simvastatin decreases the remodeling index by reducing lesion, but not reference plaque and EEM area. However, simvastatin does not affect direct evidence of remodeling (delta EEM/delta plaque) obtained using serial IVUS studies.

Coronary artery calcification and changes in atheroma burden in response to established medical therapies

OBJECTIVES

This study sought to determine the relationship between coronary calcification and plaque progression in response to established medical therapies.

BACKGROUND

Coronary calcification correlates with the extent of atherosclerosis and predicts clinical outcome.

METHODS

Atheroma volume was determined in serial intravascular ultrasound pullbacks in matched arterial segments of 776 patients with angiographic coronary artery disease. A calcium grade at baseline was assigned for each image (total 28,876) (0 = no calcium, 1 = calcium with acoustic shadowing <90 degrees and 2 = calcium with shadowing >90 degrees). Patients with a calcium index (average of calcium scores in a pullback) below versus above the median were compared with regard to plaque burden and progression.

RESULTS

Patients with a high calcium index were older (59 vs. 54 years, p < 0.001), more likely to be male (80% vs. 68%, p < 0.001), and more likely to have a history of hypertension (71% vs. 64%, p = 0.03). These patients had a greater percentage atheroma volume (PAV) (45% vs. 34%, p < 0.001), total atheroma volume (TAV) (210 vs. 151 mm3, p < 0.001), and percentage of images with maximal plaque thickness >0.5 mm (93% vs. 72%, p < 0.001). The continuous rate of change in PAV (1.1 +/- 0.4% vs. 0.8 +/- 0.4%, p = 0.34) and TAV (1.7 +/- 2.1% vs. -0.1 +/- 2.2%, p = 0.37) was similar in patients with a lower and higher calcium index, respectively. A lower calcium index was associated with a higher rate of patients showing substantial change in atheroma burden (at least 5% change in PAV, 70% vs. 53%, p < 0.001).

CONCLUSIONS

Calcific plaques are more resistant to undergoing changes in size in response to systemic interventions targeting atherosclerotic risk factors.

Thematic review series: Patient-Oriented Research. Imaging atherosclerosis: state of the art

The ability to image obstructive arterial disease brought about a revolution in clinical cardiovascular care; the development of newer technologies that image arterial wall thicknesses, areas, volumes, and composition allows valid imaging of atherosclerosis for the first time. Development of noninvasive imaging of atherosclerosis has further led to a quantum shift in research in the field by enabling the study of asymptomatic populations and thus allowing investigators to focus on preclinical disease without the many biases associated with the study of symptomatic patients. These noninvasive investigations have broad implications for clinical care as well. Coronary angiography, computed tomographic (CT) imaging of coronary calcium, intravascular ultrasound, multidetector CT angiography, B mode ultrasound of the carotid arteries, and MRI of the carotid arteries all have unique strengths and weaknesses for imaging atherosclerosis. Certain of these techniques are extremely useful as outcome variables for clinical trials, and others are uniquely useful as predictors of the risk of cardiovascular disease. All are informative in one way or another with regard to the role of plaque remodeling and composition in disease causation. CT and MRI technology are advancing very rapidly, and research and clinical uses of these imaging modalities promise to further advance our understanding of atherosclerosis and its prevention.

Remodeling Index Compared to Actual Vascular Remodeling in Atherosclerotic Left Main Coronary Arteries as Assessed With Long-Term (≥12 Months) Serial Intravascular Ultrasound

OBJECTIVES

We present the remodeling index (RI) versus serial intravascular ultrasound (IVUS) data.

BACKGROUND

The RI, derived by comparing lesion external elastic membrane (EEM) cross-sectional area versus the reference at one time point, is used in various IVUS studies as a substitute of true remodeling (change in EEM over time), assuming that it represents true remodeling.

METHODS

We studied 46 non-stenotic left main arteries using serial IVUS (follow-up 18 +/- 8 months). Plaques were divided into subgroups according to the follow-up RI: follow-up RI >1 (n = 27) versus follow-up RI < or =1 (n = 19).

RESULTS

Lesions with a follow-up RI >1 had an increase in lumen despite an increase in plaque because of an increase in EEM. Conversely, lesions with a follow-up RI < or =1 had a reduction in lumen as a result of both a plaque increase and EEM decrease. Overall, the follow-up RI correlated directly with changes in lesion site EEM (baseline-to-follow-up). Although there was no correlation between the follow-up RI and changes in reference EEM area, changes in reference EEM area did correlate directly with changes in lesion EEM area. In nearly 90% of lesions with a follow-up RI >1, there was a previously documented increase in EEM area. Using multivariate linear regression analysis, the follow-up RI was dependent on the baseline RI, the increase in lesion EEM area, and the decrease in reference EEM area. The follow-up RI was not dependent on changes in lesion plaque area.

CONCLUSIONS

The vast majority of left main lesions with a remodeling index >1 had evidence of a previous increase in lesion-site EEM area.

Association of plaque characterization by intravascular ultrasound virtual histology and arterial remodeling

Positive remodeling is more often observed in lesions of patients who have acute coronary syndromes or vulnerable (rupture-prone) plaques. However, there are few data that correlate plaque morphology, composition, and arterial remodeling in vivo. We evaluated coronary plaque characterization of lesions with positive remodeling using intravascular ultrasound (IVUS) radiofrequency data analysis. Seventy-seven nonbifurcation native coronary lesions (in 50 patients) were imaged in vivo using 30-MHz IVUS transducers. Lesions were classified into 4 plaque types, fibrous, fibrofatty, dense calcium, and necrotic core, by using processing of the radiofrequency signal validated in vitro. The remodeling index was calculated as the lesion external elastic membrane area divided by the proximal reference external elastic membrane area. Lesions were divided into 2 groups: positive remodeling (remodeling index>1.0, 26 lesions) and intermediate/negative remodeling (remodeling index<or=1.0, 51 lesions). Total plaque volume and the volume of each plaque type were averaged over the length of the lesion. Reference segment plaque compositions were similar. Mean lesion fibrofatty plaque area was significantly larger in lesions with positive remodeling than in lesions with intermediate/negative remodeling (1.2+/-0.7 vs 0.8+/-0.4 mm2, p=0.001; 26.3+/-6.6% vs 19.8+/-5.7%, p<0.001, of total plaque volume). The same results were obtained at the minimum lumen site and in the subgroup of patients who had acute coronary syndromes. Further, there was a linear relation between remodeling index and fibrofatty plaque area (r=0.26, p=0.02). In conclusion, in vivo IVUS radiofrequency data analysis demonstrates that positive remodeling occurs in lesions with more fibrofatty plaque.

Quantification of Calcification in Atherosclerotic Lesions

Calcification can be deposited throughout the vasculature in several forms of calcium phosphate, including calcium hydroxyapatite (CHA). Calcium accumulation in arteries by mineralization and calcium loss from bone by osteoporosis often coexist, and vascular calcification may share common mechanisms with bone remodeling. Deposition of calcification in valves and arteries diminishes the valvular or arterial wall elasticity, a major cause of aneurysm and stenosis. Obstruction of arteries by calcification and other components can lead to heart attack and stroke. Mineralization in the femoral arteries can cause intermittent claudication in the legs, causing decreased mobility. Accurate measurement of calcification is essential for identifying other factors associated with this process and ultimately for elucidating the mechanism(s) of calcification. A wide range of methods for visualizing and measuring calcification for diagnosis and treatment in vivo and for studying the calcification process ex vivo are available. This review provides a critical comparison of older established methods and newer evolving technologies for quantifying calcification.

LDL-cholesterol predicts negative coronary artery remodelling in diabetic patients: an intravascular ultrasound study

AIMS

To investigate the relationship between coronary artery remodelling and glycaemic and lipid profiles in diabetic patients.

METHODS AND RESULTS

Intravascular ultrasound analyses of 131 angiographically non-significant coronary stenoses in 80 diabetic patients were performed. The remodelling index (RI) was calculated as the ratio between total vessel area at target site and total vessel area at proximal reference, and was assessed in two ways: as a continuous variable, and as a binary categorical variable: RI<1 namely, negative remodelling (group I), or RI> or =1 (group II). Percentage cross-sectional narrowing was 57+/-13%. On average, RI was 0.93+/-0.13. Coronary shrinkage was found in 94 (71.7%) lesions. Significant inverse correlations were demonstrated between RI and total cholesterol (r=-0.26, P=0.003), apolipoprotein-B (r=-0.23, P=0.01) and LDL-cholesterol (r=-0.3, P=0.001) levels. Multivariable lineal regression analysis identified LDL-cholesterol as the only independent predictor of RI (P=0.001).

CONCLUSION

Negative remodelling is a frequent finding in diabetics and it is associated with LDL-cholesterol levels. This may contribute to the diffuse coronary artery disease observed in diabetic patients.

Impact of different definitions on the interpretation of coronary remodeling determined by intravascular ultrasound

The objective of this study was to compare the categorizations and determinants related to remodeling by the three definitions commonly used. Several morphological and intravascular ultrasound (IVUS) studies have demonstrated the fundamental importance of arterial remodeling in atherosclerosis. However, lack of consensus on how to define remodeling has led to conflicting analyses of factors that influence this process. Analysis of pre-interventional IVUS images of 514 lesions in native coronary arteries was performed. Arterial remodeling was defined as outward by definition 1, when [cross-sectional area (CSA) of the external elastic membrane (EEM) at the lesion site (EEM(lesion))]/[EEM CSA either at the proximal (EEM(prox ref)) or distal (EEM(distal ref)) reference site with the least amount of plaque] was > 1.05, intermediate when this ratio was between 0.95 and 1.05, and inward when < 0.95. Remodeling was defined as outward by definition 2 when EEM(lesion) > both EEM(prox ref) and EEM(distal ref), inward when EEM(lesion) < both EEM(prox ref) and EEM(distal ref), and intermediate when EEM(lesion) was intermediate between EEM(prox ref) and EEM(distal ref). By definition 3, vessel remodeling was defined as outward when EEM(lesion) > (EEM(prox ref) + EEM(distal ref))/2 and intermediate/inward when EEM(lesion) < or = (EEM(prox ref) + EEM(distal ref))/2. The frequency of outward remodeling was significantly higher by definitions 1 and 3 than by definition 2, whereas a higher frequency of inward remodeling was observed in definition 1, resulting in significantly different remodeling distributions between the three definitions (P < 0.0001). By multivariate logistic analysis, the only clinical determinants related to outward remodeling was younger age, and only by definition 3. IVUS determinants varied significantly between the three definitions. The only consistent determinants among the three definitions were smaller lumen CSA at the reference site and larger plaque + media CSA at the lesion site. This study demonstrates the significant impact of different remodeling definitions on the incidence and determinants of remodeling patterns. The marked variability in categorization of remodeling underscores the importance of developing a standard methodology.

Morphologic Findings of Coronary Atherosclerotic Plaques in Diabetics

OBJECTIVE

Coronary atherosclerotic plaque composition of diabetic subjects and localization of receptor for advanced glycation end products (RAGE) and its ligands have not been extensively studied.

METHODS AND RESULTS

Hearts from diabetic subjects and age, race, and sex-matched nondiabetic subjects dying suddenly were examined. Coronary arteries were dissected and lesions were evaluated for plaque burden, necrotic core size, and inflammatory infiltrate. The expression of RAGE, the RAGE-binding protein (S100-A12, EN-RAGE), and cell death (apoptosis) were also determined. Lesions from type II diabetic subjects had larger mean necrotic cores (P=0.01) and greater total and distal plaque load (P<0.001) than nondiabetic subjects. Necrotic core size correlated positively with diabetic status, independent of other risk factors. Intimal staining for macrophages, T-cells, and HLA-DR was also significantly greater in diabetic subjects (P=0.03, P=0.003, and P<0.0001), respectively. The association of increased macrophage infiltrate was independent of cholesterol levels and patient age. Expression of RAGE and EN-RAGE was significantly greater in diabetic subjects (P=0.004) and was associated with apoptotic smooth muscle cells and macrophages.

CONCLUSIONS

In sudden coronary death, inflammation and necrotic core size play a greater role in the progression of atherosclerosis in diabetic subjects. The expression of RAGE and EN-RAGE may further compromise cell survival and promote plaque destabilization.

Remodeling of coronary arteries in diabetic patients-an intravascular ultrasound study

BACKGROUND

Coronary artery remodeling is a structural change in the vessel wall and typically in response to atherosclerotic plaque. The nature of coronary remodeling has been described in different clinical situations. However, remodeling characteristics of coronary arteries of diabetic patients have never been studied.

HYPOTHESIS

We tested the hypothesis that positive remodeling of coronary artery in response to atherosclerotic plaque in diabetic patients would be less compared to nondiabetic patients.

METHODS

Coronary intravascular ultrasound analysis of data in 26 consecutive patients (12 diabetic and 14 nondiabetic) was performed. Linear regression analyses of vessel area versus plaque area were carried out to establish a relation between the degree of plaque and the extent of remodeling in diabetic and nondiabetic groups.

RESULTS

The positive remodeling quantified as the slope of the regression line was similar in both the groups (diabetic group 1.32 and nondiabetic group 0.80) when all segments with different plaque areas were considered (P > 0.05). However, the diabetic group had greater positive remodeling in segments with plaque area less than 55%, as the slope for diabetic group was 2.01 and nondiabetic group was 1.40 (P < 0.05).

CONCLUSIONS

Both the diabetic and nondiabetic patients had positive remodeling in response to atherosclerotic plaque formation. Diabetics had greater positive remodeling in the early stages of atherosclerosis compared to nondiabetics, thus providing evidence against our hypothesis. The adverse clinical outcomes in diabetics may not be due to inadequate positive remodeling of coronary arteries as previously thought.

Spectrum of remodeling behavior observed with serial long-term (>/=12 months) follow-up intravascular ultrasound studies in left main coronary arteries

Most intravascular ultrasound (IVUS) studies of arterial remodeling in native coronary arteries reported a remodeling index obtained at a single time point. We analyzed serial IVUS examinations, including the vessel cross-sectional area changes (remodeling behavior), of 60 hemodynamically nonstenotic left main lesions (baseline vs 18.4 +/- 9.4 months follow-up). Lumen reduction resulted from vessel reduction (sometimes despite plaque + media decrease), plaque + media increase (with or without vessel increase), or both. The percent annual changes in lumen area correlated strongly with changes in vessel (r = 0.84), but not with changes in plaque + media area. Plaques were classified as group A lesions, reflecting positive remodeling behavior (vessel changes >0), or group B lesions, reflecting negative (or intermediate) remodeling behavior (vessel changes <==0). Both groups did not differ significantly in demographics, laboratory data, and medications. Group A lesions (n = 40) more often showed plaque + media increase than group B lesions (32 of 40 [80%] vs 9 of 20 [45%]; p = 0.02). Group A lesions had, on average, mild annual lumen increase despite mild plaque + media increase, i.e, overcompensation of remodeling for plaque + media increase (vessel increase greater than plaque + media area increase, 19 of 40 [47%]). Conversely, group B lesions (n = 20) showed a significant lumen area reduction (-2.8 +/- 2.6 mm(2)/year) as a result of a decrease in vessel area only. Thus, serial long-term reduction of lumen size may result from vessel shrinkage (sometimes despite plaque decrease), plaque increase (with or without vessel increase), or both; overall, only the remodeling behavior has a significant relation to lumen changes. More than 30% of lesions show a negative remodeling behavior, which shows no relation to patient characteristics or initial plaque burden.

Intravascular ultrasound assessment of atherosclerosis

Atherosclerosis imaging has taken on increasing importance in the understanding of the natural history of coronary artery disease and the processes leading to luminal narrowing, as well as the assessment of disease burden and therapy efficacy. Intravascular ultrasound (IVUS) has emerged as the new gold standard for atherosclerosis imaging because it provides cross-sectional images of both the arterial wall and lumen with excellent resolution, reveals the diffuse nature of atherosclerosis and the involvement of reference segments, and takes into account vessel wall remodeling. In addition to its clinical indications, IVUS is now widely used as the primary efficacy assessment measure of several antiatherosclerotic approaches in randomized clinical trials. Advantages of IVUS include its ability to reveal antiatherosclerotic effects within a relatively short period of time and with a reasonable sample size, which is in contrast to trials assessing angiographic changes or clinical events. IVUS can also help to determine dose-response relationships in the development of novel pharmacologic agents. IVUS is currently the ideal imaging modality for clinical trials of atherosclerosis progression/regression.

Effects of lipid-lowering therapy on coronary artery remodeling

BACKGROUND

Although lipid-lowering therapy affects the luminal size of atherosclerotic coronary arteries the role of vascular remodeling has not been systematically studied.

DESIGN/METHODS

Serial three-dimensional volumetric intravascular ultrasound (IVUS) was used to study remodeling, which was defined as changes in arterial size independent of or dependent on changes in plaque size. Using an automated contour detection algorithm, a 1 mm segment of a moderate atherosclerotic lesion at the site of the maximal plaque volume at baseline was analysed. After 12 months the relationship between the absolute change in vessel volume and plaque volume was calculated in 99 patients. There was a significant relationship between changes in plaque and vessel volume, independent of plaque progression or plaque regression (decrease in plaque size, r = 0.60, P < 0.0001 and increase in plaque size, r = 0.49, P < 0.0008, respectively; the slopes of the regression equation were 1.03 and 0.80). By means of an analysis of covariance we tested whether the regression slopes were equal between groups of patients as defined by the low-density lipoprotein-cholesterol (LDL-c) level achieved with lipid-lowering therapy.

RESULTS

Only patients with plaque progression and a LDL-c level < 100 mg/dl had a significantly smaller slope than patients with a LDL-c level > 100 mg/dl (-0.14 compared with 1.14, P = 0.003 ), indicating diminished coronary remodeling.

CONCLUSIONS

Serial volumetric IVUS confirms the existence of both positive and negative remodeling in relation to an increase and decrease in plaque volume. It has been shown that the outward remodeling process is diminished in patients with plaque progression and intensive lipid-lowering therapy.

Intravascular ultrasound assessment of patterns of arterial remodeling in the absence of significant reference segment plaque burden in patients with coronary artery disease

OBJECTIVES

We evaluated the impact of reference vessel segment plaque burden on lesion remodeling. Intravascular ultrasound (IVUS) assessment of lesion remodeling compares lesions to reference segments. However, reference segments are rarely disease-free and, therefore, have also undergone remodeling changes.

METHODS

Pre-intervention IVUS was obtained in 274 patients with right coronary artery lesions selected because the right coronary artery has less tapering and fewer side branches than the left anterior descending or left circumflex artery. Standard IVUS definitions were used. Patients were divided according to reference vessel segment plaque burden: group A (minimal reference disease, n = 91), both proximal and distal reference plaque burden <20%; group B (n = 91), either proximal or distal reference plaque burden 20% to 40% but both < or =40%; and group C (n = 92), either proximal or distal reference plaque burden >40%.

RESULTS

The remodeling index measured 0.98 +/- 0.16 in group A (range, 0.68 to 1.47), 1.04 +/- 0.18 in group B (range, 0.67 to 1.91), and 1.04 +/- 0.15 in group C (range, 0.74 to 1.70), analysis of variance p = 0.0208 (p = 0.0234 group A vs. group B and p = 0.0012 group A vs. group C, but p = 0.8 group B vs. group C). Positive, intermediate, and negative remodeling were observed in 24 (26%), 24 (26%), and 43 lesions (48%) in group A; 36 (40%), 28 (30%), and 27 lesions (30%) in group B; and 34 (37%), 39 (42%), and 19 lesions (21%) in group C, respectively (p = 0.0022).

CONCLUSIONS

Negative remodeling occurs commonly in coronary lesions with minimal reference segment disease. Negative remodeling is not just an "artifact" introduced by comparing lesions to diseased reference segments.

Effects of cardiovascular risk factors on coronary artery remodeling in patients with mild atherosclerosis

BACKGROUND

Vascular remodeling counteracts luminal encroachment during the progression of coronary artery disease (CAD) and modulates the manifestation of hemodynamically significant lesions. However, the role of cardiovascular risk factors for coronary remodeling has not been fully clarified.

METHODS

Therefore, we investigated the role of local plaque burden and systemic risk factors on coronary vascular remodeling in 25 patients (49 segments) with angiographically normal or minimally diseased coronary arteries by intravascular ultrasound. In an additional 12 patients without coronary atherosclerosis, physiological vessel tapering was determined and used to calculate the extent of remodeling in diseased segments.

RESULTS

An increase in local plaque burden was directly correlated with positive vascular remodeling (r = 0.54, P<0.001). However, cardiovascular risk factors like hypertension (P<0.001) and hypercholesterolemia (P = 0.03) were associated with reduced positive or even negative remodeling. Moreover, the total number of classical cardiovascular risk factors was a strong predictor for reduced positive remodeling (P for trend <0.001). In contrast, coronary flow reserve, a measure of shear stress imposed on the vessel wall, positively correlated with compensatory enlargement (r = 0.44, P = 0.002). By multivariate analysis, plaque burden (P = 0.001), hypertension (P = 0.001) and coronary flow reserve (P = 0.018) proved to be independent determinants of vascular remodeling of epicardial coronary arteries.

CONCLUSIONS

Cardiovascular risk factors impair compensatory arterial enlargement and even predispose to shrinkage of epicardial arteries during the initial stage of atherosclerosis. Reduced positive vascular remodeling might contribute to the clinical manifestation of CAD by facilitating the development of flow-limiting stenoses in patients at risk.

High-resolution MR imaging of human atherosclerotic femoral arteries in vivo: validation with intravascular ultrasound

PURPOSE

To establish a magnetic resonance (MR) imaging protocol for noninvasive in-vivo analysis of atherosclerotic femoral artery segments in humans and to compare the results to those of intravascular ultrasonography (IVUS).

MATERIALS AND METHODS

In seven patients with peripheral arterial occlusive disease, 20 femoral arterial segments per person were examined by high-resolution (HR) MR imaging and IVUS. Comparison was possible in 123 of 140 segments. MR imaging was performed at 1.5 T with use of a three-dimensional (3D) time-of-flight sequence with an in-plane resolution of 0.78 x 0.49 mm(2). 3D contrast-enhanced MR angiography was used for exact positioning of the HR MR imaging slices. IVUS (3.5 F, 40 MHz) was performed with use of a motorized pullback system. Parameters analyzed included cross-sectional lumen area (LA), vessel area (VA), and extent of vessel wall calcification.

RESULTS

Agreement between IVUS and HR MR imaging was analyzed with use of the Bland-Altman method. The paired LA measurements were in close agreement: the Bland-Altman mean bias in LA was -0.4 mm with a precision of +/-5.1 mm (P =.062). As a result of dorsal echo extinction in IVUS, VA measurements were feasible in only 74 of 140 segments. VA measurements were moderately correlated (r = 0.74; P <.0001), and a 25% overestimation by HR MR imaging compared to IVUS was observed. Intra- and interobserver comparisons for LA and VA measured with HR MR imaging did not show significant differences. Vessel wall calcifications were classified with a sensitivity of 91%, a specificity of 93%, and an accuracy of 93%.

CONCLUSIONS

The MR imaging protocol introduced in the present study permits precise assessment of LA and extent of calcification in peripheral arterial occlusive disease in vivo. HR MR imaging shows high concordance with IVUS and may have the potential for noninvasive therapy monitoring.

Effect of disease eccentricity on compensatory remodeling of coronary arteries: evidence from intravascular ultrasound before interventions

BACKGROUND

Compensatory remodeling occurs to maintain lumen area in human coronary vessels. However, few data exist regarding the relationship between vessel remodeling and plaque distribution. Therefore, we studied coronary sites with or without remodeling by intravascular ultrasound and correlated with disease distribution.

METHODS AND RESULTS

A total of 90 coronary sites with significant stenosis (>50%) from 80 patients were examined before interventions. For identifying the vessel remodeling, external elastic membrane (EEM) area was measured at the stenotic sites and the adjacent proximal and distal sites. The reference EEM area was calculated by averaging proximal and distal EEM areas, and percent enlargement of the EEM area was calculated by the formula: [(stenosis EEM area-reference EEM area)/reference EEM area]x100. Plaque area was determined by reducing the lumen from EEM areas. The maximal (max) and minimal (min) distances from the center of the lumen to the EEM were also measured, and the disease eccentricity index was calculated by the formula: [(max-min)/max]. The lesion was defined as eccentric if the index was >0.5 and as concentric if <or=0.5. There were 39 eccentric and 51 concentric lesions. The enlargement remodeling was observed at 32 lesions with the enlargement of EEM area of 28.0+/-16.0% (5.5 to 71.3%). Enlargement was more frequently observed in the eccentric than in concentric lesions (P<0.05). However, within 32 stenoses, which showed enlargement, there was no difference in enlargement between eccentric (n=19, 25.6+/-21.0%) and concentric lesions (n=13, 21.5+/-12.0%). Also, there was no statistical correlation between the increase in plaque area and % enlargement of EEM area irrespective of plaque morphology.

CONCLUSIONS

These data demonstrate that in advanced coronary disease compensatory enlargement occurs more frequently at the eccentric than concentric coronary lesions. However, the EEM area was limited to expand regardless of the disease morphology.

Short-term mortality of myocardial infarction patients with diabetes or hyperglycaemia during admission

AIM

The hypothesis that patients with hyperglycaemia during admission, regardless of previous diagnosis of diabetes, have worse prognosis than those with normal glucose values is controversial. The objective was to assess the role of hyperglycaemia on short-term mortality after myocardial infarction (MI).

METHODS AND RESULTS

A cohort study nested in a prospective registry of MI patients in the reference hospital of Gerona, Spain was performed. All consecutive MI patients under 75 were registered between 1993 and 1996. Patient and clinical characteristics, including previous diagnosis of diabetes, glycaemia on admission and in the next four days, were recorded. Patients with glycaemia on admission or four day mean glycaemia >6.67 mmol/l were considered hyperglycaemic. The main outcome measure was mortality at 28 days. Of 662 patients with MI included, 195 (29.7%) had previously known diabetes mellitus, but 457 (69.0%) had glycaemia >6.67 mmol/l on admission. Patients with hyperglycaemia on admission were older, more often female, more frequently had a previous diagnosis of diabetes, developed more complications, and had higher 28 day mortality. The effect of admission glycaemia >6.67 mmol/l on 28 day mortality was independent of major confounding factors, particularly previous diagnosis of diabetes (OR=4.20, 95% confidence intervals 1.18 to 14.96).

CONCLUSIONS

Higher 28 day mortality was observed among MI patients with glycaemia on admission >6.67 mmol/l compared with patients with lower levels, independently of major confounding variables and, particularly, previous diagnosis of diabetes. This early, simple, and inexpensive marker of bad prognosis after MI should prompt the application of more aggressive treatment of MI and risk factors and, probably, of glycaemia during admission.

Impact of deep vessel wall injury and vessel stretching on subsequent arterial remodeling after balloon angioplasty: a serial intravascular ultrasound study

BACKGROUND

Arterial remodeling has been shown to be responsible for lumen narrowing after nonstent interventions.

METHODS

To examine the impact of deep vessel wall injury (DI) after balloon angioplasty on the subsequent vessel remodeling process, we performed serial intravascular ultrasound (IVUS) analysis in 47 native coronary artery lesions that underwent balloon angioplasty. An IVUS study was performed before and after balloon angioplasty and repeated at follow-up. Vessel and lumen area were measured at the narrowest site before intervention. Plaque area was calculated as vessel area minus lumen area. DI was defined as the presence of plaque/vessel wall fracture deep in the medial layer (sonolucent zone by IVUS) after angioplasty.

RESULTS

After angioplasty, DI was present in 18 (38%, DI group) and absent in 29 (62%, non-DI group) of lesions. During follow-up, changes in vessel area in the DI group were significantly larger than in the non-DI group (P =.007). There were no significant differences in changes in plaque area. A trend toward greater late lumen loss was observed in the non-DI group (P =.05). In the DI group, changes in lumen area correlated better with changes in vessel area (r = 0.81, P <.0001) than with changes in plaque area (r = 0.32, P =.20). However, in the non-DI group, changes in lumen area correlated with changes in plaque area (r = -0.55, P =.002), but not with changes in vessel area (r = 0.30, P =.11).

CONCLUSIONS

Deep vessel wall injury after balloon angioplasty is associated with the magnitude of the subsequent vessel remodeling process. The differences in the remodeling process may have implications regarding adjunctive therapies to prevent restenosis after balloon angioplasty.

Morphological predictors of arterial remodeling in coronary atherosclerosis

BACKGROUND

Although arterial remodeling in atherosclerotic arteries affects luminal patency, the role of plaque components has not been systematically studied.

METHODS AND RESULTS

Coronary segments (n=2885) were harvested from the hearts of 36 patients who died of severe coronary artery disease after perfusion fixation. Remodeling was determined by morphometric analysis of 657 sections selected as reference segments and 1318 segments with atheromatous plaques. Atherosclerotic plaques were identified as fibroatheroma, thin-cap fibroatheroma, intraplaque hemorrhage with or without rupture or erosion, or total occlusion. Plaque components consisted of calcification, lipid core, macrophage burden, and fibrosis. There was no correlation between plaque area and lumen size in proximal arteries, unlike middle and distal segments, which demonstrated a significant correlation. Marked expansion of the internal elastic lamina (IEL) occurred in plaque hemorrhages with or without and thin-cap fibroatheroma (vulnerable plaque), whereas in erosions and total occlusions there was shrinkage of the IEL. Macrophage burden, lipid core size, calcium (in fibrous plaque and lipid core), and medial atrophy were all associated with positive remodeling; fibrous areas, however, were negatively associated with remodeling.

CONCLUSIONS

Inflammation, calcification, and medial thinning are primary determinants of positive remodeling, which appears to be a feature of plaque instability.

PPARgamma and atherosclerosis: effects on cell growth and movement

Atherosclerosis is a major vascular complication of diabetes and the primary cause of mortality in persons with this disease. Metabolic abnormalities related to the Insulin Resistance Syndrome or Metabolic Syndrome may importantly contribute to the increased risk of atherosclerosis associated with diabetes. Thiazolidinediones (TZDs) are oral insulin sensitizers in broad clinical use that enhance insulin-stimulated glucose uptake into skeletal muscle. TZDs can also improve cardiovascular risk factors and exert direct effects on vascular cells to potentially retard the atherosclerotic process. Direct vascular effects of TZDs likely result from their activity as ligands for the nuclear receptor, PPARgamma. All of the major cell types in the vasculature express PPARgamma, including intimal macrophages and vascular smooth muscle cells (VSMCs) in human atheroma. TZDs block VSMC growth by inducing cell cycle arrest in G1 through an inhibition of retinoblastoma protein phosphorylation. Migration of monocytes and VSMCs is also inhibited by TZDs, possibly through decreased matrix metalloproteinase production. Activation of PPARgamma by TZDs in macrophages induces ABCA1 transporter expression to promote reverse cholesterol transport. These antiatherogenic activities may also occur in vivo because TZDs have been shown to inhibit lesion formation in several animal models. Thus, TZD activation of PPARgamma may protect against atherosclerosis both by normalizing proatherogenic metabolic abnormalities of the insulin resistance/diabetes milieu and through an inhibition of vascular cell growth and movement.

Plaque burden, arterial remodeling and plaque vulnerability: determined by systemic factors?

OBJECTIVES

This study was designed to determine whether arterial remodeling and plaque vulnerability are influenced by systemic factors.

BACKGROUND

Atherosclerotic luminal narrowing is caused by gradual plaque growth and arterial remodeling. In the acute phase, luminal narrowing may be accelerated by acute thrombus formation, usually precipitated by rupture of a vulnerable plaque.

METHODS

Femoral arteries were obtained from elderly individuals at autopsy. Pairs of atherosclerotic femoral arteries from 42 individuals were examined. The arteries were divided in 1-cm intervals. Plaque size, the mode of arterial remodeling and histopathologic characteristics of plaque vulnerability (lipid-rich core and plaque inflammation) were compared between right and left femoral arteries obtained from the same individual. A role for systemic factors was assumed if a phenomenon was equally present in both arteries.

RESULTS

There was concordance in average plaque size (r(2) = 0.5, p < 0.001), expansive remodeling (kappa = 0.42, p = 0.007) and occurrence of plaques containing a large lipid-rich core (kappa = 0.60, p = 0.001), but no concordance in plaque inflammation (kappa = 0.067, p = 0.61) between right and left arteries.

CONCLUSIONS

These results suggest that not only the amount of atherosclerosis, but also arterial remodeling and lipid deposition in plaques, are influenced by systemic factors. The nonhomogeneous distribution of inflammation in atherosclerotic arteries supports the hypothesis that plaque inflammation is locally affected.

Abnormal longitudinal, base-to-apex myocardial perfusion gradient by quantitative blood flow measurements in patients with coronary risk factors

BACKGROUND

A longitudinal, base-to-apex myocardial perfusion gradient has been described in patients with coronary artery disease (CAD) and was attributed to diffuse coronary luminal narrowing. We asked whether an abnormal perfusion gradient also existed in patients without CAD but with coronary risk factors. We measured myocardial blood flow (MBF) with (13)N-ammonia and PET at rest and during hyperemia in patients with coronary risk factors but without CAD.

METHODS AND RESULTS

Regional MBF was measured in absolute units with (13)N-ammonia and PET at rest and during dipyridamole hyperemia in 36 patients with coronary risk factors (age, 55+/-10 years) and in 36 age-matched (age, 53+/-10 years) and in 28 young (age, 25+/-5 years) normal subjects. MBF was determined globally, for each of the 3 coronary territories, and in the mid and mid-to-apical sections of the left ventricle (LV). Myocardial perfusion on qualitative analysis was normal at rest and during hyperemia, and no flow defects were present. MBF in absolute units was similar in the 3 coronary territories. However, hyperemic MBFs in the mid-to-apical LV section were lower than in the mid LV section in the "at-risk" group (2.04+/-0.61 versus 1.71+/-0.40 mL. min(-1). g(-1); P<0.004) but not in the age-matched or in the young normal subjects.

CONCLUSIONS

The abnormal longitudinal, base-to-apex perfusion gradient observed during dipyridamole MBF suggests the presence of a functional and/or structural alteration of the coronary circulation associated with coronary risk factors, possibly reflecting developing coronary atherosclerosis or preclinical CAD.

Lesion characteristics of acute myocardial infarction: an investigation with intravascular ultrasound

OBJECTIVE

To use intravascular ultrasound (IVUS) to compare plaque morphology in acute myocardial infarction and stable angina pectoris.

DESIGN

Retrospective study.

SETTING

Primary care hospital.

PATIENTS

59 consecutive cases of acute myocardial infarction and 50 consecutive cases of stable angina pectoris.

METHODS

IVUS was used before coronary intervention.

MAIN OUTCOME MEASURES

Plaque morphology (incidence of eccentric plaque, subtle dissections, low echoic thrombus, calcification, echolucent areas, and bright speckled echo material), assessed visually using IVUS.

RESULTS

There were no significant differences in plaque eccentricity or calcification between the two groups, but low echoic thrombus (acute myocardial infarction 15% v stable angina pectoris 0%), subtle dissections (37% v 4%), echolucent areas (31% v 0%), and bright speckled echo material (90% v 0%) were more common in the infarction group than in the stable angina group (p < 0.001 for all). There was a longer time between the onset of symptoms and the IVUS examination in patients with low echoic thrombus than in those without (p < 0.03).

CONCLUSIONS

Low echoic thrombus, subtle dissections, echolucent areas, and bright speckled echo material are morphological characteristics associated with plaque at the time of acute myocardial infarction. These findings correspond pathologically to ruptured plaque.

Intravascular ultrasound findings of negative arterial remodeling at sites of focal coronary spasm in patients with vasospastic angina

BACKGROUND

There are few data about the intravascular ultrasound (IVUS) findings in patients with vasospastic angina, especially regarding patterns of vascular remodeling.

METHODS AND RESULTS

Coronary spasm was documented by angiography and electrocardiographic evidence of ischemia in 36 patients after administration of ergonovine (cumulative doses up to 350 microg). After relief of spasm with 1000 microg of intracoronary nitroglycerin, quantitative angiography and IVUS imaging were performed and analyzed by standard methods. The 36 focal spasm sites were compared with the proximal and distal reference segments. The angiographic baseline minimum lumen diameter measured 1.78 +/- 0.66 mm, which decreased to 0.66 +/- 0.38 mm with ergonovine provocation (P <.0001), increased to 2.66 +/- 0.64 mm after intracoronary nitroglycerin (P <.0001 compared with baseline and after ergonovine), and did not change after IVUS imaging (2.66 +/- 0.63, P =.9). By IVUS, atherosclerotic lesions were observed at all coronary spasm sites; the mean plaque burden measured 56% at the spasm site and 35% at the reference. Spasm site plaque composition was hypoechoic in 31 and hyperechoic, noncalcific in 5; there was no calcium. The mean eccentricity index (maximum divided by minimum plaque thickness) was 6.7. Positive remodeling (spasm site arterial area greater than proximal reference) was present in 5; intermediate remodeling (proximal reference greater than spasm site greater than distal reference arterial area) was present in 7; and negative remodeling (spasm site arterial area less than distal reference) was present in 24.

CONCLUSIONS

Sites of vasospasm in patients with variant angina showed characteristics of early atherosclerosis, except for an unusually high incidence of negative arterial remodeling.

Serial in vivo MRI documents arterial remodeling in experimental atherosclerosis

BACKGROUND

Arterial remodeling in response to atherosclerosis may be outward (positive) or inward (negative) and is an important mechanism in the clinical manifestations of atherosclerosis and restenosis after percutaneous coronary interventions. Postmortem and intravascular ultrasound studies of arterial remodeling do not allow serial and noninvasive data to be obtained. In a rabbit model of atherosclerosis, we sought to validate MRI as a new tool for documentation of arterial remodeling.

METHODS AND RESULTS

Watanabe heritable hyperlipidemic rabbits underwent serial MRI at baseline and 6 months after aortic balloon denudation. The lumen area had a small but significant (P=0.006) increase, from 4.36+/-0.16 to 4. 89+/-0.12 mm(2). There was a large, significant (P<0.0001) increase in the outer wall area, from 7.96+/-0.19 to 10.46+/-0.19 mm(2). The vessel wall area (a marker of atherosclerotic burden) increased significantly (P<0.0001), from 3.61+/-0.07 to 5.57+/-0.09 mm(2). Thus, the increase in atherosclerotic burden over time was completely accounted for by positive arterial remodeling. The subgroup used for histopathological validation confirmed a significant (P<0.0001) agreement between histopathology and MRI for assessment of all 3 parameters.

CONCLUSIONS

MRI can provide serial and noninvasive data about the arterial wall, allowing assessment of arterial remodeling in this rabbit model. Thus, MRI appears to be a useful tool for the investigation of arterial remodeling both in native atherosclerosis and after percutaneous coronary intervention.