Objectives We sought to investigate whether and what carotid plaque characteristics predict systemic cardiovascular outcomes in patients with clinically established atherosclerotic disease. Background Advancements in atherosclerosis imaging have allowed assessment of various plaque characteristics, some of which are more directly linked to the pathogenesis of acute cardiovascular events compared to plaque burden. Methods As part of an event-driven clinical trial (AIM-HIGH), subjects with clinically established atherosclerotic disease underwent multicontrast carotid MRI to detect plaque tissue composition and high-risk features. Prospective associations between MRI measurements and the AIM-HIGH primary endpoint (fatal and non-fatal myocardial infarction, ischemic stroke, hospitalization for acute coronary syndrome, and symptom-driven revascularization) were analyzed using Cox proportional hazard models. Results Of 232 subjects recruited, 214 (92.2%) with diagnostic image quality constituted the study population (mean age: 61±9 years; males: 82%; statin use: 94%). During a median follow-up of 35.1 months, 18 (8.4%) subjects reached the AIM-HIGH endpoint. High lipid content (hazard ratio per one-standard-deviation increase in % lipid core volume: 1.57, p=0.002) and thin/ruptured fibrous cap (hazard ratio: 4.31, p=0.003) in carotid plaques were strongly associated with the AIM-HIGH endpoint. Intraplaque hemorrhage had a low prevalence (8%) and was marginally associated with the AIM-HIGH endpoint (hazard ratio: 3.00, p=0.053). High calcification content (hazard ratio per one-standard-deviation increase in % calcification volume: 0.66, p=0.20), plaque burden metrics, and clinical risk factors were not significantly associated with the AIM-HIGH endpoint. The associations between carotid plaque characteristics and the AIM-HIGH endpoint changed little after adjusting for clinical risk factors, plaque burden, or AIM-HIGH randomized treatment assignment. Conclusions Among patients with clinically established atherosclerotic disease, carotid plaque lipid content and fibrous cap status were strongly associated with systemic cardiovascular outcomes. Markers of carotid plaque vulnerability may serve as novel surrogate markers for systemic atherothrombotic risk.

No abstract

This study sought to determine the multicenter reproducibility of magnetic resonance imaging (MRI) and the compatibility of different scanner platforms in assessing carotid plaque morphology and composition. A standardized multi-contrast MRI protocol was implemented at 16 imaging sites (GE: 8; Philips: 8). Sixty-eight subjects (61 ± 8 years; 52 males) were dispersedly recruited and scanned twice within 2 weeks on the same magnet. Images were reviewed centrally using a streamlined semiautomatic approach. Quantitative volumetric measurements on plaque morphology (lumen, wall, and outer wall) and plaque tissue composition [lipid-rich necrotic core (LRNC), calcification, and fibrous tissue] were obtained. Inter-scan reproducibility was summarized using the within-subject standard deviation, coefficient of variation (CV) and intraclass correlation coefficient (ICC). Good to excellent reproducibility was observed for both morphological (ICC range 0.98–0.99) and compositional (ICC range 0.88–0.96) measurements. Measurement precision was related to the size of structures (CV range 2.5–4.9 % for morphology, 36–44 % for LRNC and calcification). Comparable measurement variability was found between the two platforms on both plaque morphology and tissue composition. In conclusion, good to excellent inter-scan reproducibility of carotid MRI can be achieved in multicenter settings with comparable measurement precision between platforms, which may facilitate future multicenter endeavors that use serial MRI to monitor atherosclerotic plaque progression.

Association between clinical factors and high-risk plaque features such as thin or ruptured cap, intra-plaque hemorrhage (IPH), presence of Lipid Rich Necrotic Core (LRNC) and increased LRNC volume as assessed by Magnetic Resonance Imaging (MRI) was examined in patients with established vascular disease in AIM-HIGH. A total of 214 subjects underwent carotid MRI and had acceptable image quality for assessment of plaque burden, tissue contents and MRI-modified AHA lesion type by a Core Lab. We found that 77% of subjects had carotid plaques, 52% had lipid-containing plaques, and 11% had advanced, AHA type-VI lesions with possible surface defect, IPH or mural thrombus. Type-VI lesions were associated with older age (OR=2.6 per 5 years increase, p<0.001). After adjusting for age, these lesions were associated with history of cerebrovascular disease (OR=4.1, p=0.01), higher levels of Lipoprotein(a) (OR=2.0 per 1 SD increase, p=0.02) and larger %wall volume (%WV; OR=4.6 per 1 SD increase, p<0.001), but, were negatively associated with metabolic syndrome (OR=0.2, p=0.02). Presence of LRNC was associated with male gender (OR=3.2, p=0.02) and %WV (OR=3.8 per 1 SD, p<0.001), but, was negatively associated with diabetes (OR=0.4, p=0.02) and HDL-C levels (OR=0.7 per 1 SD, p=0.02). Increased %LRNC was associated with %WV (regression coefficient=0.36, p<0.001) and negatively associated with ApoA1 levels (regression coefficient=−0.20, p=0.03). In conclusions, older age, male gender, history of cerebrovascular disease, larger plaque burden, higher Lp(a), and lower HDL-C or ApoA1 have statistically significant associations with high-risk plaque features. Metabolic syndrome and diabetes showed negative associations in this population.

Objective We investigated relationships between statin and niacin/statin combination therapy and the concentration of high density lipoprotein particles (HDL-P) and cholesterol efflux capacity, two HDL metrics that might better assess cardiovascular disease (CVD) risk than HDL-cholesterol (HDL-C) levels. Approach In the Carotid Plaque Composition Study, 126 subjects with a history of CVD were randomized to atorvastatin or combination therapy (atorvastatin/niacin). At baseline and after 1 year of treatment, the concentration of HDL and its three subclasses (small, medium, and large) were quantified by calibrated ion mobility analysis (HDL-PIMA). We also measured total cholesterol efflux from macrophages and ABCA1-specific cholesterol efflux capacity. Results Atorvastatin decreased low density lipoprotein cholesterol (LDL-C) by 39% and raised HDL-C by 11% (P=0.0001), but did not increase HDL-PIMA or macrophage cholesterol efflux. Combination therapy raised HDL-C by 39% (P<0.0001), but increased HDL-PIMA by only 14%. Triglyceride levels did not correlate with HDL-PIMA (P=0.39), in contrast to their strongly negative correlation with HDL-C (P<0.0001). Combination therapy increased macrophage cholesterol efflux capacity (16%, P<0.0001) but not ABCA1-specific efflux. ABCA1-specific cholesterol efflux capacity decreased significantly (P=0.013) in statin-treated subjects, with or without niacin therapy. Conclusions Statin therapy increased HDL-C levels but failed to increase HDL-PIMA. It also reduced ABCA1-specific cholesterol efflux capacity. Adding niacin to statin therapy increased HDL-C and macrophage efflux, but had much less effect on HDL-PIMA. It also failed to improve ABCA1-specific efflux, a key cholesterol exporter in macrophages. Our observations raise the possibility that niacin might not target the relevant atheroprotective population of HDL.

There is a high incidence of new T2DM at 8% over 4 years among Chinese. Larger BMI, higher glucose levels, and lower levels of ApoA1 are significantly and independently associated with new T2DM. Lower ApoA1 improves the risk prediction of new type 2 diabetes when it was added to the existing risk models.

No abstract

BackgroundThe aim of this study is to investigate the inter-scan reproducibility of kinetic parameters in atherosclerotic plaque using dynamic contrast-enhanced (DCE) cardiovascular magnetic resonance (CMR) in a multi-center setting at 3T.MethodsCarotid arteries of 51 subjects from 15 sites were scanned twice within two weeks on 3T scanners using a previously described DCE-CMR protocol. Imaging data with protocol compliance and sufficient image quality were analyzed to generate kinetic parameters of vessel wall, expressed as transfer constant (Ktrans) and plasma volume (vp). The inter-scan reproducibility was evaluated using intra-class correlation coefficient (ICC) and coefficient of variation (CV). Power analysis was carried out to provide sample size estimations for future prospective study.ResultsTen (19.6%) subjects were found to suffer from protocol violation, and another 6 (11.8%) had poor image quality (n = 6) in at least one scan. In the 35 (68.6%) subjects with complete data, the ICCs of Ktrans and vp were 0.65 and 0.28, respectively. The CVs were 25% and 62%, respectively. The ICC and CV for vp improved to 0.73 and 28% in larger lesions with analyzed area larger than 25 mm2. Power analysis based on the measured CV showed that 50 subjects per arm are sufficient to detect a 20% difference in change of Ktrans over time between treatment arms with 80% power without consideration of the dropout rate.ConclusionThe result of this study indicates that quantitative measurement from DCE-CMR is feasible to detect changes with a relatively modest sample size in a prospective multi-center study despite the limitations. The relative high dropout rate suggested the critical needs for intensive operator training, optimized imaging protocol, and strict quality control in future studies.