Atherosclerotic plaque stabilization and regression: a review of clinical evidence

Atherosclerotic plaque results from a complex interplay between lipid deposition, inflammatory changes, cell migration and arterial wall injury. Over the past two decades, clinical trials utilizing invasive arterial imaging modalities, such as intravascular ultrasonography, have shown that reducing levels of atherogenic lipoproteins, mainly serum LDL-cholesterol (LDL-C), to very low levels can safely reduce overall atherosclerotic plaque burden and favourably modify plaque composition. Classically, this outcome has been achieved with intensive statin therapy. Since 2016, newer and potent lipid-lowering strategies, such as proprotein convertase subtilisin-kexin type 9 inhibition, have shown incremental effects on plaque regression and risk of clinical events. Despite maximal reduction in plasma LDL-C levels, considerable residual cardiovascular risk remains in some patients. Therefore, there is a need to study therapeutic approaches that address residual risk beyond LDL-C reduction to promote plaque stabilization or regression. Contemporary imaging modalities, such as coronary computed tomography angiography, enable non-invasive assessment of the overall atherosclerotic plaque burden as well as of certain local plaque characteristics. This technology could allow further study of plaque stabilization and regression using novel therapeutic approaches. Non-invasive plaque assessment might also offer the potential to guide personalized management strategies if validated for this purpose.

Drug intervention as an emerging concept for secondary prevention in patients with coronary disease

Non-culprit lesion-related coronary events are a significant concern in patients with coronary artery disease (CAD) undergoing coronary intervention. Since several studies using intra-coronary imaging modalities have reported a high prevalence of vulnerable plaques in non-culprit lesions at the initial coronary event, the immediate stabilization of these plaques by intensive pharmacological regimens may contribute to the reduction in the adverse events. Although current treatment guidelines recommend the titration of statin and other drugs to attain the treatment goal of low-density lipoprotein cholesterol (LDL-C) level in patients with CAD, the early prescription of strong LDL-C lowering drugs with more intensive regimen may further reduce the incidence of recurrent cardiovascular events. In fact, several studies with intensive regimen have demonstrated a higher percentage of patients with the attainment of LDL-C treatment goal in the early phase following discharge. In addition to many imaging studies showing plaque stabilization by LDL-C lowering drugs, several recent reports have shown the efficacy of early statin and proprotein convertase subtilisin/kexin type 9 inhibitors on the immediate stabilization of non-culprit coronary plaques. To raise awareness regarding this important concept of immediate plaque stabilization and subsequent reduction in the incidence of recurrent coronary events, the term 'Drug Intervention' has been introduced and gradually applied in the clinical field, although a clear definition is lacking. The main target of this concept is patients with acute coronary syndrome as a higher prevalence of vulnerable plaques in non-culprit lesions in addition to the worse clinical outcomes has been reported in recent imaging studies. In this article, we discuss the backgrounds and the concept of drug intervention.

Role of Lipid-Lowering and Anti-Inflammatory Therapies on Plaque Stabilization

Atherosclerosis is the predominant underlying etiopathology of coronary artery disease. Changes in plaque phenotype from stable to high risk may spur future major adverse cardiac events (MACE). Different pharmacological therapies have been implemented to mitigate this risk. Over the last two decades, intravascular imaging modalities have emerged in clinical studies to clarify how these therapies may affect the composition and burden of coronary plaques. Lipid-lowering agents, such as statins, ezetimibe, and proprotein convertase subtilisin/kexin type 9 inhibitors, were shown not only to reduce low-density lipoprotein levels and MACE but also to directly affect features of coronary plaque vulnerability. Studies have demonstrated that lipid-lowering therapy reduces the percentage of atheroma volume and number of macrophages and increases fibrous cap thickness. Future studies should answer the question of whether pharmacological plaque stabilization may be sufficient to mitigate the risk of MACE for selected groups of patients with atherosclerotic coronary disease.

Effect of ezetimibe-statin combination therapy vs. statin monotherapy on coronary atheroma phenotype and lumen stenosis in patients with coronary artery disease: a meta-analysis and trial sequential analysis

Background

Evidence indicates that the addition of ezetimibe to statin therapy reduces cardiovascular events. However, the impact of ezetimibe-statin combination therapy on coronary plaque regression, plaque stabilization, and diameter stenosis remains a matter of controversy.

Methods

We performed electronic searches in PubMed, Web of Knowledge, and the Cochrane Central Register of Controlled Trials to identify eligible trials assessing the effects of ezetimibe-statin combination therapy versus statin monotherapy reporting at least one outcome among total atheroma volume (TAV), minimum fibrous cap thickness (FCT), lumen volume (LV), and lumen area (LA) derived from intravascular imaging modalities of intravascular ultrasound (IVUS) and optical coherence tomography (OCT). We used the random-effects model and performed trial sequential analysis (TSA) during this meta-analysis.

Results

Eleven articles with a total of 926 individuals (460 in the dual-lipid-lowering therapy group and 466 in the statin monotherapy group) were included in the final meta-analysis. Compared to statin monotherapy, ezetimibe-statin combination therapy was associated with significantly decreased TAV [WMD = -3.17, 95% CI (-5.42 to -0.92), and p = 0.006], with no effect on the LV of the coronary artery [WMD = -0.52, 95% CI (-2.24 to 1.21), and p = 0.56], the LA of the coronary artery [WMD = 0.16, 95% CI (-0.10-0.42), and p = 0.22], or minimum FCT thickness [WMD = 19.11, 95%CI (-12.76-50.97)].

Conclusion

In patients with coronary artery disease, ezetimibe-statin combination therapy resulted in a significant regression in TAV compared to statin monotherapy, whereas no overall improvements of minimum FCT or lumenal stenosis were observed.

Meta-analysis and trial sequential analysis of ezetimibe for coronary atherosclerotic plaque compositions

Background: Lipid aggregation, inflammatory cell infiltration, fibrous cap formation, and disruption are the major causes of atherosclerotic cardiovascular disease (ASCVD) and the pathologic features of atherosclerotic plaques. Although ezetimibe’s role in decreasing blood lipids is widely known, there are insufficient data to determine which part of the drug has an effect on atherosclerotic plaque compositions.

Objective: The study aimed to systematically evaluate the efficacy of ezetimibe for coronary atherosclerotic plaque compositions.

Methods: Two researchers independently searched the PubMed, Embase, Cochrane Library, and Web of Science databases for randomized controlled trials (RCTs) on the efficacy of ezetimibe for coronary atherosclerotic plaques from inception until 22 January 2023. The meta-analysis and trial sequential analysis (TSA) were performed using Stata 14.0 and TSA 0.9.5.10 Beta software, respectively.

Results: Four RCTs were finally included this study, which comprised 349 coronary artery disease patients. Meta-analysis findings showed that, compared with the control group, intervention measures could effectively reduce the fibro-fatty plaque (FFP) volume [WMD = −2.90, 95% CI (−4.79 and −1.00), and p = 0.003 < 0.05]; there were no significant difference in the reduction of fibrous plaque (FP) volume [WMD = −4.92, 95% CI (−11.57 and 1.74), and p = 0.15 > 0.05], necrotic core (NC) volume [WMD = −2.26, 95% CI (−6.99 and 2.46), and p = 0.35 > 0.05], and change dense calcification (change DC) volume [WMD = −0.07, 95% CI (−0.34 and 0.20), and p = 0.62 > 0.05] between the treatment group and the control group. TSA findings showed more studies are still required to confirm the efficacy of ezetimibe for FP and NC in the future.

Conclusion: Compared to the control group, ezetimibe significantly decreased FFP, but it had no statistically significant difference on FP, NC, or change DC. According to TSA, further research will be required to confirm the efficacy of ezetimibe for FP and NC in the future.

Coronary artery properties in atherosclerosis: A deep learning predictive model

In this work an Artificial Neural Network (ANN) was developed to help in the diagnosis of plaque vulnerability by predicting the Young modulus of the core (E _core ) and the plaque (E _plaque ) of atherosclerotic coronary arteries. A representative in silico database was constructed to train the ANN using Finite Element simulations covering the ranges of mechanical properties present in the bibliography. A statistical analysis to pre-process the data and determine the most influential variables was performed to select the inputs of the ANN. The ANN was based on Multilayer Perceptron architecture and trained using the developed database, resulting in a Mean Squared Error (MSE) in the loss function under 10^-7, enabling accurate predictions on the test dataset for E _core and E _plaque . Finally, the ANN was applied to estimate the mechanical properties of 10,000 realistic plaques, resulting in relative errors lower than 3%.

Additive effects of ezetimibe, evolocumab, and alirocumab on plaque burden and lipid content as assessed by intravascular ultrasound: A PRISMA-compliant meta-analysis

BACKGROUND

The additive effects of ezetimibe, evolocumab or alirocumab on lipid level, plaque volume, and plaque composition using intravascular ultrasound (IVUS) remain unclear.

METHODS

According to the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement, we performed a systematic review and meta-analysis of trials assessing the effects of ezetimibe, evolocumab, and alirocumab on coronary atherosclerosis using IVUS. The primary outcome was change in total atheroma volume (TAV), and the secondary outcomes were changes and differences in plaque composition and lipid content.

RESULTS

Data were collected from 9 trials, involving 917 patients who received ezetimibe, evolocumab or alirocumab in addition to a statin and 919 patients who received statins alone. The pooled estimate demonstrated a significant reduction in TAV with the addition of ezetimibe and favorable effects of evolocumab and alirocumab on TAV. Subgroup analysis also supported favorable effects of evolocumab and alirocumab on TAV, according to baseline TAV, gender, type 2 diabetes mellitus, and prior stain use. Addition of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor to statin therapy resulted in significant reductions in low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), and triglycerides (TG), but not in high-density lipoprotein cholesterol (HDL-C). The pooled estimate also showed significant favorable effects of ezetimibe on LDL-C, TC, and TG, but an insignificant effect on HDL-C. Patients who received ezetimibe showed similar changes in the necrotic core, fibro-fatty plaque, fibrous plaque, and dense calcification compared with patients not treated with ezetimibe.

CONCLUSIONS

The addition of ezetimibe to statin therapy may further reduce plaque and lipid burdens but may not modify plaque composition. Although current evidence supports a similar impact from the addition of PCSK9 inhibitors to statin therapy, more evidence is needed to confirm such an effect.

Coronary Atherosclerotic Plaque Regression: JACC State-of-the-Art Review

Over the last 3 decades there have been substantial improvements in treatments aimed at reducing cardiovascular (CV) events. As these treatments have been developed, there have been parallel improvements in coronary imaging modalities that can assess plaque volumes and composition, using both invasive and noninvasive techniques. Plaque progression can be seen to precede CV events, and therefore, many studies have longitudinally assessed changes in plaque characteristics in response to various treatments, aiming to demonstrate plaque regression and improvements in high-risk features, with the rationale being that this will reduce CV events. In the past, decisions surrounding treatments for atherosclerosis have been informed by population-based risk scores for initiation in primary prevention and low-density lipoprotein cholesterol levels for titration in secondary prevention. If outcome data linking plaque regression to reduced CV events emerge, it may become possible to directly image plaque treatment response to guide management decisions.

Effect of Atorvastatin (10 mg) and Ezetimibe (10 mg) Combination Compared to Atorvastatin (40 mg) Alone on Coronary Atherosclerosis

It remains inconclusive whether the additional low-density lipoprotein cholesterol (LDL-C) lowering effects of ezetimibe added to statin on coronary atherosclerosis and clinical outcomes are similar to those of statin monotherapy in the setting of comparable LDL-C reduction. We aimed to determine whether there were distinguishable differences in their effects on coronary atherosclerosis with intermediate stenosis between the combination of moderate-intensity statin plus ezetimibe and high-intensity statin monotherapy. Forty-one patients with stable angina undergoing percutaneous coronary intervention were randomized to receive either atorvastatin 10 mg plus ezetimibe 10 mg (ATO10/EZE10) or atorvastatin 40 mg alone (ATO40). The intermediate lesions were evaluated using a near-infrared spectroscopy-intravascular ultrasonography at baseline and after 12 months in 37 patients. The primary endpoint was percent atheroma volume (PAV). Mean LDL-C levels were significantly reduced by 40% and 38% from baseline in the ATO10/EZE10 group (n = 18, from 107 mg/dL to 61 mg/dL) and ATO40 group (n = 19, from 101 mg/dL to 58 mg/dL), respectively, without between-group difference. The absolute change of PAV was -2.9% in the ATO10/EZE10 group and -3.2% in the ATO40 group. The mean difference (95% confidence interval) for the absolute change in PAV between the 2 groups was 0.5% (-2.4% to 2.8%), which did not exceed the pre-defined non-inferiority margin of 5%. There was no significant reduction in lipid core burden index in both groups. In conclusion, the combination of atorvastatin 10 mg and ezetimibe 10 mg showed comparable LDL-C lowering and regression of coronary atherosclerosis in the intermediate lesions, compared with atorvastatin 40 mg alone.

The effects of lipid-lowering therapy on coronary plaque regression: a systematic review and meta-analysis

To assess the influence of lipid-lowering therapy on coronary plaque volume, and to identify the LDL and HDL targets for plaque regression to provide a comprehensive overview. The databases searched (from inception to 15 July 2020) to identify prospective studies investigating the impact of lipid-lowering therapy on coronary plaque volume and including quantitative measurement of plaque volume by intravascular ultrasound after treatment. Thirty-one studies that included 4997 patients were selected in the final analysis. Patients had significantly lower TAV (SMD: 0.123 mm³; 95% CI 0.059, 0.187; P = 0.000) and PAV (SMD: 0.123%; 95% CI 0.035, 0.212; P = 0.006) at follow-up. According to the subgroup analyses, TAV was significantly reduced in the LDL < 80 mg/dL and HDL > 45 mg/dL group (SMD: 0.163 mm³; 95% CI 0.092, 0.234; P = 0.000), and PAV was significantly reduced in the LDL < 90 mg/dL and HDL > 45 mg/dL group (SMD: 0.186%; 95% CI 0.081, 0.291; P = 0.001).Thirty-one studies that included 4997 patients were selected in the final analysis. Patients had significantly lower TAV (SMD: 0.123 mm³; 95% CI 0.059, 0.187; P = 0.000) and PAV (SMD: 0.123%; 95% CI 0.035, 0.212; P = 0.006) at follow-up. According to the subgroup analyses, TAV was significantly reduced in the LDL < 80 mg/dL and HDL > 45 mg/dL group (SMD: 0.163 mm³; 95% CI 0.092, 0.234; P = 0.000), and PAV was significantly reduced in the LDL < 90 mg/dL and HDL > 45 mg/dL group (SMD: 0.186%; 95% CI 0.081, 0.291; P = 0.001). Our meta-analysis suggests that not only should LDL be reduced to a target level of < 80 mg/dL, but HDL should be increased to a target level of > 45 mg/dL to regress coronary plaques.

Trial Registration PROSPERO identifier: CRD42019146170.

The role of intracoronary imaging in translational research

Atherosclerotic cardiovascular disease is a key public health concern worldwide and leading cause of morbidity, mortality and health economic costs. Understanding atherosclerotic plaque microstructure in relation to molecular mechanisms that underpin its initiation and progression is needed to provide the best chance of combating this disease. Evolving vessel wall-based, endovascular coronary imaging modalities, including intravascular ultrasound (IVUS), optical coherence tomography (OCT) and near-infrared spectroscopy (NIRS), used in isolation or as hybrid modalities, have been advanced to allow comprehensive visualization of the pathological substrate of coronary atherosclerosis and accurately measure temporal changes in both the vessel wall and plaque characteristics. This has helped further our appreciation of the natural history of coronary artery disease (CAD) and the risk for major adverse cardiovascular events (MACE), evaluate the responsiveness to conventional and experimental therapeutic interventions, and assist in guiding percutaneous coronary intervention (PCI). Here we review the use of different imaging modalities for these purposes and the lessons they have provided thus far.

Role of non-statin lipid-lowering therapy in coronary atherosclerosis regression: a meta-analysis and meta-regression

BACKGROUND

Several studies have investigated the association between non-statin lipid-lowering therapy and regression of atherosclerosis. However, these studies were mostly small and their results were not always robust. The objectives were: (1) to define if a dual lipid-lowering therapy (statin + non-statin drugs) is associated with coronary atherosclerosis regression, estimated by intravascular ultrasound (IVUS); (2) to assess the association between dual lipid-lowering-induced changes in low density lipoprotein cholesterol (LDL-C) and non-high-density-lipoprotein cholesterol (non-HDL-C) levels and atherosclerosis regression.

METHODS

A meta-analysis including trials of non-statin lipid-lowering therapy, reporting LDL-C, non-HDL-C and total atheroma volume (TAV) with a minimum of 6 months of follow-up was performed. The primary endpoint was defined as the change in TAV measured from baseline to follow-up, comparing groups of subjects on statins alone versus combination of statin and non-statin drugs. The random-effects model and meta-regression were performed.

RESULTS

Eight eligible trials of non-statin lipid-lowering drugs (1759 patients) were included. Overall, the dual lipid-lowering therapy was associated with a significant reduction in TAV [- 4.0 mm3 (CI 95% -5.4 to - 2.6)]; I2 = 0%]. The findings were similar in the stratified analysis according to the lipid-lowering drug class (ezetimibe or PCSK9 inhibitors). In the meta-regression, a 10% decrease in LDL-C or non-HDL-C levels, was associated, respectively, with 1.0 mm3 and 1.1 mm3 regressions in TAV.

CONCLUSION

These data suggests the addition of ezetimibe or PCSK9 inhibitors to statin therapy results in a significant regression of TAV. Reduction of coronary atherosclerosis observed with non-statin lipid-lowering therapy is associated to the degree of LDL-C and non-HDL-C lowering. Therefore, it seems reasonable to achieve lipid goals according to cardiovascular risk and regardless of the lipid-lowering strategy used (statin monotherapy or dual treatment).

Ezetimibe for the prevention of cardiovascular disease and all-cause mortality events

BACKGROUND

Cardiovascular disease (CVD) remains an important cause of mortality and morbidity, and high levels of blood cholesterol are thought to be the major modifiable risk factors for CVD. The use of statins is the preferred treatment strategy for the prevention of CVD, but some people at high-risk for CVD are intolerant to statin therapy or unable to achieve their treatment goals with the maximal recommended doses of statin. Ezetimibe is a selective cholesterol absorption inhibitor, whether it has a positive effect on CVD events remains uncertain. Results from clinical studies are inconsistent and a thorough evaluation of its efficacy and safety for the prevention of CVD and mortality is necessary.

OBJECTIVES

To assess the efficacy and safety of ezetimibe for the prevention of CVD and all-cause mortality.

SEARCH METHODS

We searched the CENTRAL, MEDLINE, Embase and Web of Science on 27 June 2018, and two clinical trial registry platforms on 11 July 2018. We checked reference lists from primary studies and review articles for additional studies. No language restrictions were applied.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared ezetimibe versus placebo or ezetimibe plus other lipid-modifying drugs versus other lipid-modifying drugs alone in adults, with or without CVD, and which had a follow-up of at least 12 months.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion, extracted data, assessed risk of bias and contacted trialists to obtain missing data. We performed statistical analyses according to the Cochrane Handbook for Systematic Reviews of Interventions and used the GRADE to assess the quality of evidence.

MAIN RESULTS

We included 26 RCTs randomising 23,499 participants. All included studies assessed effects of ezetimibe plus other lipid-modifying drugs compared with other lipid-modifying drugs alone or plus placebo. Our findings were driven by the largest study (IMPROVE-IT), which had weights ranging from 41.5% to 98.4% in the different meta-analyses.Ezetimibe with statins probably reduces the risk of major adverse cardiovascular events compared with statins alone (risk ratio (RR) 0.94, 95% confidence interval (CI) 0.90 to 0.98; a decrease from 284/1000 to 267/1000, 95% CI 256 to 278; 21,727 participants; 10 studies; moderate-quality evidence). Trials reporting all-cause mortality used ezetimibe with statin or fenofibrate and found they have little or no effect on this outcome (RR 0.98, 95% CI 0.91 to 1.05; 21,222 participants; 8 studies; high-quality evidence). Adding ezetimibe to statins probably reduces the risk of non-fatal myocardial infarction (MI) (RR 0.88, 95% CI 0.81 to 0.95; a decrease from 105/1000 to 92/1000, 95% CI 85 to 100; 21,145 participants; 6 studies; moderate-quality evidence) and non-fatal stroke (RR 0.83, 95% CI 0.71 to 0.97; a decrease 32/1000 to 27/1000, 95% CI 23 to 31; 21,205 participants; 6 studies; moderate-quality evidence). Trials reporting cardiovascular mortality added ezetimibe to statin or fenofibrate, probably having little or no effect on this outcome (RR 1.00, 95% CI 0.89 to 1.12; 19457 participants; 6 studies; moderate-quality evidence). The need for coronary revascularisation might be reduced by adding ezetimibe to statin (RR 0.94, 95% CI 0.89 to 0.99; a decrease from 196/1000 to 184/1000, 95% 175 to 194; 21,323 participants; 7 studies); however, no difference in coronary revascularisation rate was observed when a sensitivity analysis was limited to studies with a low risk of bias.In terms of safety, adding ezetimibe to statins may make little or no difference in the risk of hepatopathy (RR 1.14, 95% CI 0.96 to 1.35; 20,687 participants; 4 studies; low-quality evidence). It is uncertain whether ezetimibe increase or decrease the risk of myopathy (RR 1.31, 95% CI 0.72 to 2.38; 20,581 participants; 3 studies; very low-quality evidence) and rhabdomyolysis, given the wide CIs and low event rate. Little or no difference in the risk of cancer, gallbladder-related disease and discontinuation due to adverse events were observed between treatment groups. For serum lipids, adding ezetimibe to statin or fenofibrate might further reduce the low-density lipoprotein cholesterol (LDL-C), total cholesterol and triglyceride levels and likely increase the high-density lipoprotein cholesterol levels; however, substantial heterogeneity was detected in most analyses.None of the included studies reported on health-related quality of life.

AUTHORS' CONCLUSIONS

Moderate- to high-quality evidence suggests that ezetimibe has modest beneficial effects on the risk of CVD endpoints, primarily driven by a reduction in non-fatal MI and non-fatal stroke, but it has little or no effect on clinical fatal endpoints. The cardiovascular benefit of ezetimibe might involve the reduction of LDL-C, total cholesterol and triglycerides. There is insufficient evidence to determine whether ezetimibe increases the risk of adverse events due to the low and very low quality of the evidence. The evidence for beneficial effects was mainly obtained from individuals with established atherosclerotic cardiovascular disease (ASCVD, predominantly with acute coronary syndrome) administered ezetimibe plus statins. However, there is limited evidence regarding the role of ezetimibe in primary prevention and the effects of ezetimibe monotherapy in the prevention of CVD, and these topics thus requires further investigation.

The effect of combined ezetimibe and statin therapy versus statin therapy alone on coronary plaque volume assessed by intravascular ultrasound: A systematic review and meta-analysis

BACKGROUND

Current guidelines recommend an intensive lipid-lowering therapy to achieve the low-density lipoprotein cholesterol (LDL-C) target in patients with high risk of cardiovascular disease. Former studies suggested adding ezetimibe to statin therapy in the above setting may promote plaque changes; however, this effect has not been consistently reported.

METHODS

Electronic searches were performed in MEDLINE, EMBASE, and Cochrane library on November 30, 2017 to identify prospective trials assessing the effects of combined ezetimibe and statin therapy versus statin therapy alone on atheroma volume using intravascular ultrasound. The effect size between treatment groups within individual studies was assessed by weighted mean difference (MD) using a random-effects model.

RESULTS

Eight studies were obtained for systematic review and 6 of them compromising total of 583 subjects that meet the criteria were meta-analyzed. There was a significant reduction from baseline to follow-up in total atheroma volume with an MD of -3.71 mm³ (95% confidence interval: -5.98 to -1.44, P < .001), whereas analysis for percent atheroma volume demonstrated weighted MD of - 0.77% (-1.68 to 0.14, P = .10). A substantial decrease in LDL-C was observed with MD -16.75 mg/dL (-20.89 to -12.60, P < .00001).

CONCLUSION

The addition of ezetimibe to statin therapy is effective in reducing total atheroma volume assessed by intravascular ultrasound and also resulted in effective reduction of plasma LDL-C levels.

Comparison of the Effects of Ezetimibe-Statin Combination Therapy on Major Adverse Cardiovascular Events in Patients with and without Diabetes: A Meta-Analysis

BACKGROUND

Ezetimibe-statin combination therapy has been found to reduce low density lipoprotein cholesterol levels and the risk of major adverse cardiovascular events (MACEs) in large trials. We sought to examine the differential effect of ezetimibe on MACEs when added to statins according to the presence of diabetes.

METHODS

Randomized clinical trials with a sample size of at least 50 participants and at least 24 weeks of follow-up that compared ezetimibe-statin combination therapy with a statin- or placebo-controlled arm and reported at least one MACE, stratified by diabetes status, were included in the meta-analysis and meta-regression.

RESULTS

A total of seven trials with 28,191 enrolled patients (mean age, 63.6 years; 75.1% men; 7,298 with diabetes [25.9%]; mean follow-up, 5 years) were analysed. MACEs stratified by diabetes were obtained from the published data (two trials) or through direct contact (five trials). No significant heterogeneity was observed among studies (I²=14.7%, P=0.293). Ezetimibe was associated with a greater reduction of MACE risk in subjects with diabetes than in those without diabetes (pooled relative risk, 0.84 vs. 0.93; P(heterogeneity)=0.012). In the meta-regression analysis, the presence of diabetes was associated with a greater reduction of MACE risk when ezetimibe was added to statins (β=0.87, P=0.038).

CONCLUSION

Ezetimibe-statin combination therapy was associated with greater cardiovascular benefits in patients with diabetes than in those without diabetes. Our findings suggest that ezetimibe-statin combination therapy might be a useful strategy in patients with diabetes at a residual risk of MACEs.

Role of dual lipid-lowering therapy in coronary atherosclerosis regression: Evidence from recent studies

Despite recent therapeutic advances, there is an unmet need in cardiovascular disease prevention. Clinical trials and meta-analyses have established that LDL-C lowering, particularly by statin therapy, reduces the progression of coronary atherosclerosis and the risk of coronary events. Insufficient LDL-C reduction and high residual risk in a significant proportion of statin-treated patients signify that additional therapies are required to deliver more effective coronary care. Pharmacological inhibition of cholesterol absorption (with ezetimibe) and PCSK9 activity (with evolocumab or alirocumab) provides potentially useful approaches for the therapeutic modulation of LDL-C metabolism in statin-treated patients. In recent trials, combination strategies involving a statin and non-statin agent (ezetimibe or evolocumab) have been shown to promote coronary atherosclerosis regression and improve cardiovascular outcomes in patients with moderate-to-high cardiovascular risk. This review summarizes recent evidence on the effects of dual lipid-lowering therapy on coronary atherosclerosis.

Predicting Locations of High-Risk Plaques in Coronary Arteries in Patients Receiving Statin Therapy

Features of high-risk coronary artery plaques prone to major adverse cardiac events (MACE) were identified by intravascular ultrasound (IVUS) virtual histology (VH). These plaque features are: thin-cap fibroatheroma (TCFA), plaque burden PB ≥ 70%, or minimal luminal area MLA ≤ 4 mm². Identification of arterial locations likely to later develop such high-risk plaques may help prevent MACE. We report a machine learning method for prediction of future high-risk coronary plaque locations and types in patients under statin therapy. Sixty-one patients with stable angina on statin therapy underwent baseline and one-year follow-up VH-IVUS non-culprit vessel examinations followed by quantitative image analysis. For each segmented and registered VH-IVUS frame pair ( ), location-specific ( mm) vascular features and demographic information at baseline were identified. Seven independent support vector machine classifiers with seven different feature subsets were trained to predict high-risk plaque types one year later. A leave-one-patient-out cross-validation was used to evaluate the prediction power of different feature subsets. The experimental results showed that our machine learning method predicted future TCFA with correctness of 85.9%, 81.7%, and 77.0% (G-mean) for baseline plaque phenotypes of TCFA, thick-cap fibroatheroma, and non-fibroatheroma, respectively. For predicting PB ≥ 70%, correctness was 80.8% for baseline PB ≥ 70% and 85.6% for 50% ≤ PB < 70%. Accuracy of predicted MLA ≤ 4 mm² was 81.6% for baseline MLA ≤ 4 mm² and 80.2% for 4 mm² < MLA ≤ 6 mm². Location-specific prediction of future high-risk coronary artery plaques is feasible through machine learning using focal vascular features and demographic variables. Our approach outperforms previously reported results and shows the importance of local factors on high-risk coronary artery plaque development.

Plaque volume and plaque risk profile in diabetic vs. non-diabetic patients undergoing lipid-lowering therapy: a study based on 3D intravascular ultrasound and virtual histology

Background

Coronary atherosclerosis progresses faster in patients with diabetes mellitus (DM) and causes higher morbidity and mortality in such patients compared to non-diabetics ones (non-DM). We quantify changes in plaque volume and plaque phenotype during lipid-lowering therapy in DM versus non-DM patients using advanced intracoronary imaging.

Methods

We analyzed data from 61 patients with stable angina pectoris included to the PREDICT trial searching for prediction of plaque changes during intensive lipid-lowering therapy (40 mg rosuvastatin daily). Geometrically correct, fully 3-D representation of the vascular wall surfaces and intravascular ultrasound virtual histology (IVUS-VH) defined tissue characterization was obtained via fusion of two-plane angiography and IVUS-VH. Frame-based indices of plaque morphology and virtual histology analyses were computed and averaged in 5 mm long baseline/follow-up registered vessel segments covering the entire length of the two sequential pullbacks (baseline, 1-year). We analyzed 698 5-mm-long segments and calculated the Liverpool active plaque score (LAPS).

Results

Despite reaching similar levels of LDL cholesterol (DM 2.12 ± 0.91 mmol/l, non-DM 1.8 ± 0.66 mmol/l, p = 0.21), DM patients experienced, compared to non-DM ones, higher progression of mean plaque area (0.47 ± 1.15 mm² vs. 0.21 ± 0.97, p = 0.001), percent atheroma volume (0.7 ± 2.8% vs. − 1.4 ± 2.5%, p = 0.007), increase of LAPS (0.23 ± 1.66 vs. 0.13 ± 1.79, p = 0.018), and exhibited more locations with TCFA (Thin-Cap Fibro-Atheroma) plaque phenotype in 5 mm vessel segments (20.3% vs. 12.5%, p = 0.01). However, only non-DM patients reached significant decrease of LDL cholesterol. Plaque changes were more pronounced in PIT (pathologic intimal thickening) compared to TCFA with increased plaque area in both phenotypes in DM patients.

Conclusion

Based on detailed 3D analysis, we found advanced plaque phenotype and further atherosclerosis progression in DM patients despite the same reached levels of LDLc as in non-DM patients.

Trial registration ClinicalTrials.gov identifier: NCT01773512

Effect of ezetimibe on plasma adipokines: a systematic review and meta-analysis

AIMS

Statins are known to influence the status of adipokines, which play a key role in the pathophysiology of cardiometabolic diseases. As the effect of ezetimibe as an add-on to statin therapy on the impact of statins on plasma adipokines levels is currently unclear, the aim of the present study was to investigate this through a meta-analysis of controlled trials.

METHODS

A systematic review was performed, followed by a bibliographic search in PubMed, Medline, SCOPUS, Web of Science and Google Scholar databases. Quantitative data synthesis was performed using a fixed- or random-effects model (based on the level of interstudy heterogeneity) and the generic inverse variance weighting method. Effect sizes were expressed as standardized mean difference (SMD) and 95% confidence interval (CI).

RESULTS

Meta-analysis of 23 controlled trials did not suggest any significant effect of adding ezetimibe on top of statin therapy on plasma concentrations of adiponectin (SMD 0.34, 95% CI -0.28, 0.96; P = 0.288), leptin (SMD -0.75, 95% CI: -2.35, 0.85; P = 0.360), plasminogen activator inhibitor 1 (SMD -1.06, 95% CI: -2.81, 0.69; P = 0.236) and interleukin 6 (SMD 0.30, 95% CI: -0.08, 0.67; P = 0.124). However, significantly greater reductions in plasma concentrations of tumour necrosis factor α (TNF-α) (SMD -0.48, 95% CI -0.87, -0.08; P = 0.018) were achieved with ezetimibe/statin combination therapy.

CONCLUSIONS

The results suggested that ezetimibe add-on to statin therapy is associated with an enhanced TNF-α-lowering effect compared with statin monotherapy. Owing to the emerging role of TNF-α in the pathogenesis of metabolic disorders, further investigations are required to unveil the translational relevance of this TNF-α-lowering effect.

Pathologic Intimal Thickening Plaque Phenotype: Not as Innocent as Previously Thought. A Serial 3D Intravascular Ultrasound Virtual Histology Study

INTRODUCTION AND OBJECTIVES

Pathologic intimal thickening (PIT) has been considered a benign plaque phenotype. We report plaque phenotypic changes in a baseline/follow-up intravascular ultrasound-based virtual histology study.

METHODS

A total of 61 patients with stable coronary artery disease were analyzed from the HEAVEN trial (89 patients randomized between routine statin therapy vs atorvastatin 80mg and ezetimibe 10mg) with serial intravascular ultrasound imaging of nonculprit vessels. We compared changes in 693 baseline and follow-up 5-mm long segments in a novel risk score, Liverpool Active Plaque Score (LAPS), plaque parameters, and plaque composition.

RESULTS

The PIT showed the highest increase of risk score and, with fibrous plaque, also the LAPS. Necrotic core (NC) abutting to the lumen increased in PIT (22 ± 51.7; P = .0001) and in fibrous plaque (17.9 ± 42.6; P = .004) but decreased in thin cap fibroatheroma (TCFA) (⿿15.14 ± 52.2; P = .001). The PIT was the most likely of all nonthin cap fibroatheroma plaque types to transform into TCFA at follow-up (11% of all TCFA found during follow-up and 35.9% of newly-developed TCFA), but showed (together with fibrous plaque) the lowest stability during lipid-lowering therapy (24.7% of PIT remained PIT and 24.5% of fibrous plaque remained fibrous plaque).

CONCLUSIONS

Over the 1-year follow-up, PIT was the most dynamic of the plaque phenotypes and was associated with an increase of risk score and LAPS (together with fibrous plaque), NC percentage (together with fibrous plaque) and NC abutting to the lumen, despite a small reduction of plaque volume during lipid-lowering therapy. The PIT was the main source for new TCFA segments.

Therapeutic modulation of the natural history of coronary atherosclerosis: lessons learned from serial imaging studies

Despite advances in risk prediction, preventive and therapeutic strategies, atherosclerotic cardiovascular disease remains a major public health challenge worldwide, carrying considerable morbidity, mortality and health economic burden. There continues to be a need to better understand the natural history of this disease to guide the development of more effective treatment, integral to which is the rapidly evolving field of coronary artery imaging. Various imaging modalities have been refined to enable detailed visualization of the pathological substrate of atherosclerosis, providing accurate and reproducible measures of coronary plaque burden and composition, including the presence of high-risk characteristics. The serial application of such techniques, including coronary computed tomography angiography (CTA), intravascular ultrasound (IVUS) and optical coherence tomography (OCT) have uncovered important insights into the progression of coronary plaque over time in patients with stable and unstable coronary artery disease (CAD), and its responsiveness to therapeutic interventions. Here we review the use of different imaging modalities for the surveillance of coronary atherosclerosis and the lessons they have provided about the modulation of CAD by both traditional and experimental therapies.

Oxidative stress and early atherosclerosis: novel antioxidant treatment

Atherosclerotic lesions initiate in regions characterized by low shear stress and reduced activity of endothelial atheroprotective molecules such as nitric oxide, which is the key molecule managing vascular homeostasis. The generation of reactive oxygen species from the vascular endothelium is strongly related to various enzymes, such as xanthine oxidase, endothelial nitric oxide synthase and nicotinamide-adenine dinucleotide phosphate oxidase. Several pharmaceutical agents, including angiotensin converting enzyme inhibitors, angiotensin receptors blockers and statins, along with a variety of other agents, have demonstrated additional antioxidant properties beyond their principal role. Reports regarding the antioxidant role of vitamins present controversial results, especially those based on large scale studies. In addition, there is growing interest on the role of dietary flavonoids and their potential to improve endothelial function by modifying the oxidative stress status. However, the vascular-protective role of flavonoids and especially their antioxidant properties are still under investigation. Indeed, further research is required to establish the impact of the proposed new therapeutic strategies in atherosclerosis.

Simultaneous Registration of Location and Orientation in Intravascular Ultrasound Pullbacks Pairs Via 3D Graph-Based Optimization

A novel method is reported for simultaneous registration of location (axial direction) and orientation (circumferential direction) of two intravascular ultrasound (IVUS) pullbacks of the same vessel taken at different times. Monitoring plaque progression or regression (e.g., during lipid treatment) is of high clinical relevance. Our method uses a 3D graph optimization approach, in which the cost function jointly reflects similarity of plaque morphology and plaque/perivascular image appearance. Graph arcs incorporate prior information about temporal correspondence of the two IVUS sequences and limited angular twisting between consecutive IVUS images. Additionally, our approach automatically identifies starting and ending frame pairs in the two IVUS pullbacks. Validation of our method was performed in 29 pairs of IVUS baseline/follow-up pullback sequences consisting of 8 622 IVUS image frames in total. In comparison to manual registration by three experts, the average location and orientation registration errors ranged from 0.72 mm to 0.79 mm and from 7.3(°) to 9.3(°), respectively, all close to the inter-observer variability with no difference being statistically significant (p = NS). Rotation angles determined by our automated approach and expert observers showed high correlation (r(2) of 0.97 to 0.98) and agreed closely (mutual bias between the automated method and expert observers ranged from -1.57(°) to 0.15(°)). Compared with state-of-the-art approaches, the new method offers lower errors in both location and orientation registration. Our method offers highly automated and accurate IVUS pullback registration and can be employed in IVUS-based studies of coronary disease progression, enabling more focal studies of coronary plaque development and transition of vulnerability.

Involvement of Rho-associated protein kinase (ROCK) and bone morphogenetic protein-binding endothelial cell precursor-derived regulator (BMPER) in high glucose-increased alkaline phosphatase expression and activity in human coronary artery smooth muscle cells

Background

Vascular calcification is an independent risk factor for cardiovascular disease. Diabetes mellitus increases the incidence of vascular calcification; however, detailed molecular mechanisms of vascular calcification in diabetes mellitus remain unknown. We recently reported that bone morphogenetic protein-binding endothelial cell precursor-derived regulator (BMPER) regulates osteoblast-like trans-differentiation of human coronary artery smooth muscle cells (HCASMCs).

Methods

We investigated the effect of a hydroxymethylglutaryl-coenzyme A reductase inhibitor (statin), commonly used in patients with atherosclerotic diseases and diabetes mellitus, on alkaline phosphatase (ALP) mRNA expression in aortas of streptozotocin-induced diabetic mice. We also investigated the effects of the statin, Rho-associated protein kinase (ROCK) inhibitors and BMPER knockdown on ALP mRNA expression and activity in HCASMCs cultured in high glucose-containing media.

Results

Alkaline phosphatase mRNA expression was increased in aortas of streptozotocin-induced diabetic mice, and the increase was inhibited by rosuvastatin. ALP mRNA expression and activity were increased in HCASMCs cultured in high glucose-containing media, and the increases were suppressed by rosuvastatin. This suppression was reversed by the addition of mevalonate or geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate. High glucose-increased ALP mRNA expression and activity were suppressed by ROCK inhibitors. Moreover, BMPER mRNA expression was increased in diabetic mouse aortas and in HCASMCs cultured in high glucose-containing media, but was not inhibited by rosuvastatin or ROCK inhibitors. Knockdown of BMPER suppressed high glucose-increased ALP activity, but not ROCK activity in HCASMCs.

Conclusions

There are at least two independent pathways in high glucose-induced ALP activation in HCASMCs: the Rho–ROCK signaling pathway and the BMPER-dependent pathway.

The Effect of Statin Therapy on Coronary Plaque Composition Using Virtual Histology Intravascular Ultrasound: A Meta-Analysis

OBJECTIVE

Previous studies have indicated that statin therapy may promote plaque regression. However, the impact of statin therapy on plaque composition has not been clearly elucidated. We performed a meta-analysis to investigate the effect of statin therapy on coronary plaque composition as assessed by virtual histology intravascular ultrasound (VH-IVUS).

METHODS

Online databases were searched from inception to March 1, 2015. Studies providing VH-IVUS volumetric analyses of coronary plaque composition at baseline and follow-up in patients receiving statin therapy were included. Weighted mean difference (WMD) using a random-effects model was used.

RESULTS

Ten studies involving 682 patients were included. There was a substantial reduction in fibrous volume between baseline and follow-up (WMD: -2.37 mm3, 95% confidence interval (CI) -4.01 to -0.74 mm3, P=0.004), and a significant increase in dense calcium (DC) volume (WMD: 0.89 mm3, 95% CI 0.70 to 1.08 mm3, P<0.00001). No significant change was seen in fibro-fatty and necrotic core (NC) volumes. In stratified analyses, the fibrous volume was decreased significantly (WMD: -3.39 mm3, 95% CI -6.56 to -0.21 mm3, P=0.04) and the absolute DC volume (WMD: 0.99 mm3, 95% CI 0.23 to 1.76 mm3, P=0.01) was increased in the subgroup with ≥12 months follow-up, whereas no significant change was observed in the subgroup with < 12 months follow-up. Similarly, a substantial decrease in fibrous volume (WMD: -2.01 mm3, 95% CI -3.05 to -0.96 mm3, P< 0.0002) and an increase in DC volume (WMD: 0.90 mm3, 95% CI 0.70 to 1.10 mm3, P< 0.00001) were observed in the subgroup with high-intensive statin therapy, while the change in fibrous and DC volumes approached statistical significance (P=0.05 and P=0.05, respectively) in the subgroup with low-intensive statin therapy.

CONCLUSIONS

Statin treatment, particularly of high-intensity and long-term duration, induced a marked modification in coronary plaque composition including a decrease in fibrous tissue and an increase in DC.

Association between LDL-C, Non HDL-C, and Apolipoprotein B Levels with Coronary Plaque Regression

BACKGROUND

Previous reports have inferred a linear relationship between LDL-C and changes in coronary plaque volume (CPV) measured by intravascular ultrasound. However, these publications included a small number of studies and did not explore other lipid markers.

OBJECTIVE

To assess the association between changes in lipid markers and regression of CPV using published data.

METHODS

We collected data from the control, placebo and intervention arms in studies that compared the effect of lipidlowering treatments on CPV, and from the placebo and control arms in studies that tested drugs that did not affect lipids. Baseline and final measurements of plaque volume, expressed in mm3, were extracted and the percentage changes after the interventions were calculated. Performing three linear regression analyses, we assessed the relationship between percentage and absolute changes in lipid markers and percentage variations in CPV.

RESULTS

Twenty-seven studies were selected. Correlations between percentage changes in LDL-C, non-HDL-C, and apolipoprotein B (ApoB) and percentage changes in CPV were moderate (r = 0.48, r = 0.47, and r = 0.44, respectively). Correlations between absolute differences in LDL-C, non‑HDL-C, and ApoB with percentage differences in CPV were stronger (r = 0.57, r = 0.52, and r = 0.79). The linear regression model showed a statistically significant association between a reduction in lipid markers and regression of plaque volume.

CONCLUSION

A significant association between changes in different atherogenic particles and regression of CPV was observed. The absolute reduction in ApoB showed the strongest correlation with coronary plaque regression.

The difference between Asian and Western in the effect of LDL-C lowering therapy on coronary atherosclerotic plaque: a meta-analysis report

Background

The different effects of LDL-C levels and statins therapy on coronary atherosclerotic plaque between Western and Asian remain to be settled.

Methods

PubMed, EMBASE, and Cochrane databases were searched from Jan. 2000 to Sep. 2014 for randomized controlled or blinded end-points trials assessing the effects of LDL-C lowering therapy on regression of coronary atherosclerotic plaque (CAP) in patients with coronary heart disease by intravascular ultrasound. The significance of plaques regression was assessed by computing standardized mean difference (SMD) of the volume of CAP between the baseline and follow-up.

Results

Twenty trials (ten in the West and ten in Asia) were identified. For Westerns, Mean lowering LDL-C by 49.4% and/or to level 61.9 mg/dL in the group of patients with baseline mean LDL-C 123.2 mg/dL could significantly reduce the volume of CAP at follow up (SMD −0.156 mm³, 95% CI −0.248 ~ −0.064, p = 0.001). LDL-C lowering by rosuvastatin (mean 40 mg daily) could significantly decrease the volumes of CAP at follow up. For Asians, Mean lowering LDL-C by 36.1% and/or to level 84.0 mg/dL with baseline mean LDL-C 134.2 mg/dL could significantly reduce the volume of CAP at follow up (SMD −0.211 mm³, 95% CI −0.331 ~ −0.092, p = 0.001). LDL-C lowering by rosuvastatin (mean 14.1 mg daily) and atorvastatin (mean 18.9 mg daily) could significantly decrease the volumes of CAP at follow up.

Conclusions

There was a different effect of LDL-C lowering on CAP between Westerns and Asians. For regressing CAP, Asians need lower dosage of statins or lower intensity LDL-C lowering therapy than Westerns.

Assessment of plaque composition by intravascular ultrasound and near-infrared spectroscopy: from PROSPECT I to PROSPECT II

Atherosclerosis is the main cause of coronary artery disease (CAD), which is today the leading cause of death worldwide and will continue to be the first in the world in 2030. Vulnerable coronary plaques are usually characterized by a high content of necrotic core, a thin inflamed fibrous cap (intense accumulation of macrophages) and scarce presence of smooth muscle cells. None of these characteristics can be estimated by coronary angiography, which on the contrary underestimates the magnitude of atherosclerotic burden, particularly in earlier stage disease when positive vascular remodeling may allow "normal" lumen caliber despite substantial vascular wall plaque. The recognition of the ubiquity of substantial but non-flow limiting lesions that may be at high risk for subsequent plaque rupture has resulted in a paradigm shift in thinking about the pathophysiology of CAD, with the focus no longer solely on the degree of arterial luminal narrowing. This growing need for more information about coronary atherosclerosis in order to identify patients and lesions at risk for complications during PCI and for future adverse cardiac events has been the primary impetus for the development of novel intracoronary imaging methods able to detect plaque composition, in particular presence of a necrotic core/lipid pool, such as intravascular ultrasound virtual histology and near-infrared spectroscopy. These imaging technologies and their clinical and clinical/research applications are discussed in detail.

Systematic study of the effects of lowering low-density lipoprotein-cholesterol on regression of coronary atherosclerotic plaques using intravascular ultrasound

BACKGROUND

Conflicting results currently exist on the effects of LDL-C levels and statins therapy on coronary atherosclerotic plaque, and the target level of LDL-C resulting in the regression of the coronary atherosclerotic plaques has not been settled.

METHODS

PubMed, EMBASE, and Cochrane databases were searched from Jan. 2000 to Jan. 2014 for randomized controlled or blinded end-points trials assessing the effects of LDL-C lowering therapy on regression of coronary atherosclerotic plaque (CAP) in patients with coronary heart disease by intravascular ultrasound. Data concerning the study design, patient characteristics, and outcomes were extracted. The significance of plaques regression was assessed by computing standardized mean difference (SMD) of the volume of CAP between the baseline and follow-up. SMD were calculated using fixed or random effects models.

RESULTS

Twenty trials including 5910 patients with coronary heart disease were identified. Mean lowering LDL-C by 45.4% and to level 66.8 mg/dL in the group of patients with baseline mean LDL-C 123.7 mg/dL, mean lowering LDL-C by 48.8% and to level 60.6 mg/dL in the group of patients with baseline mean LDL-C 120 mg/dL, and mean lowering LDL-C by 40.4% and to level 77.8 mg/dL in the group of patients with baseline mean LDL-C 132.4 mg/dL could significantly reduce the volume of CAP at follow up (SMD -0.108 mm3, 95% CI -0.176 ~ -0.040, p = 0.002; SMD -0.156 mm3, 95% CI -0.235 ~ -0.078, p = 0.000; SMD -0.123 mm3, 95% CI -0.199 ~ -0.048, p = 0.001; respectively). LDL-C lowering by rosuvastatin (mean 33 mg daily) and atorvastatin (mean 60 mg daily) could significantly decrease the volumes of CAP at follow up (SMD -0.162 mm3, 95% CI: -0.234 ~ -0.081, p = 0.000; SMD -0.101, 95% CI: -0.184 ~ -0.019, p = 0.016; respectively). The mean duration of follow up was from 17 ~ 21 months.

CONCLUSIONS

Intensive lowering LDL-C (rosuvastatin mean 33 mg daily and atorvastatin mean 60 mg daily) with >17 months of duration could lead to the regression of CAP, LDL-C level should be reduced by >40% or to a target level <78 mg/dL for regressing CAP.

Impact on optical coherence tomographic coronary findings of fluvastatin alone versus fluvastatin + ezetimibe

Although lipid-lowering therapy with statin and ezetimibe has been reported to provide greater reduction in low-density lipoprotein cholesterol levels than statin monotherapy, the effect of supplemental therapy on plaque stabilization is yet to be fully elucidated. Cap thickness of fibroatheroma evaluated by optical coherence tomography (OCT) is a major determinant of vulnerable plaque. The primary objective of this study is to evaluate the effect of ezetimibe in addition to fluvastatin on the progression of coronary atherosclerotic plaque evaluated by OCT. Sixty-three patients with angina pectoris with intermediate, nonculprit, lipid-rich plaque lesions evaluated by OCT were enrolled. The patients were divided into 2 groups: ezetimibe (10 mg/day) + fluvastatin (30 mg/day), and fluvastatin (30 mg/day) alone, and serial OCT examinations were performed at baseline and 9-month follow-up. A total of 57 patients (ezetimibe + fluvastatin, n = 31; fluvastatin alone, n = 26) underwent serial OCT examinations. The change in low-density lipoprotein cholesterol level was significantly larger in the ezetimibe + fluvastatin group compared with fluvastatin-alone group (-34.0 ± 32.0 vs -8.3 ± 17.4 mg/dl, p <0.001). Fibrous cap thickness was significantly increased and the angle of the lipid plaque was significantly decreased in both groups. The change in the fibrous cap thickness was significantly greater in the ezetimibe + fluvastatin group (0.08 ± 0.08 mm vs 0.04 ± 0.06 mm, p <0.001). In conclusion, lipid-lowering therapy by ezetimibe + fluvastatin could increase the fibrous cap thickness of lipid-rich plaque compared with fluvastatin monotherapy.

Impacts of age on coronary atherosclerosis and vascular response to statin therapy

Age is a well-established risk factor for cardiovascular disease. Recent trials using intravascular ultrasound (IVUS) have shown that lipid-lowering therapy with statins halts the progression or induces the regression of coronary artery plaques. However, impacts of age on coronary atherosclerosis and vascular response to statin therapy have not been fully evaluated. The effects of 8-month statin therapy on coronary atherosclerosis were evaluated using virtual histology-IVUS. IVUS data were analyzed from 119 patients who were divided into two groups according to age: elderly patients (≥65 years, n = 72) and non-elderly patients (<65 years, n = 47). No patients were taking statins or other lipid-lowering therapies at baseline. At baseline, external elastic membrane (EEM) volume (17.27 vs. 14.95 mm(3)/mm, p = 0.02) and plaque volume (9.49 vs. 8.11 mm(3)/mm, p = 0.03) in the elderly patients were significantly greater than in the non-elderly patients. The EEM volume (-2.4 %, p = 0.007) and plaque volume (-3.1 %, p = 0.007) after 8-month of statin therapy had significantly decreased in the non-elderly patients but not in the elderly patients. A significant positive correlation was observed between age and percentage change in plaque volume (r = 0.265, p = 0.004). A multivariate regression analysis showed that age was a significant predictor of the percentage change in plaque volume during statin therapy (β = 0.223, p = 0.02). Coronary atherosclerosis was more advanced and vascular responses to statin therapy were attenuated in the elderly patients compared to the non-elderly patients.

Comparison of change in coronary atherosclerosis in patients with stable versus unstable angina pectoris receiving statin therapy (from the Treatment With Statin on Atheroma Regression Evaluated by Intravascular Ultrasound With Virtual Histology [TRUTH] study)

Although statin-induced regression in coronary atherosclerosis seems to be greater in patients with acute coronary syndrome than in those with stable coronary artery disease, no reports have examined this. The purpose of the present study was to compare the changes in coronary atherosclerosis in patients with stable versus unstable angina pectoris (AP). The effects of 8-month statin therapy on coronary atherosclerosis were evaluated using virtual histology intravascular ultrasound, and analyzable intravascular ultrasound data were obtained from 119 patients (83 patients with stable AP and 36 with unstable AP). A significant decrease in plaque volume was observed in patients with unstable AP (-2.2%, p = 0.02) but not in patients with stable AP. A significant increase in the necrotic-core component (0.30 mm(3)/mm, p = 0.009) was observed only in patients with unstable AP. Significant positive correlations were observed between the percentage of change in platelet-activating factor acetylhydrolase and the percentage of change in plaque volume (r = 0.346, p = 0.05) in patients with unstable AP. No significant correlations were observed in patients with stable AP. Multivariate regression analyses showed that a reduction in platelet-activating factor acetylhydrolase was associated with regression in coronary atherosclerosis, particularly of the fibrous component (β = 0.443, p = 0.003), in patients with unstable AP. In conclusion, regression of the coronary artery plaque volume was greater, although statin therapy did not halt the increases in plaque vulnerability, in patients with unstable AP compared to those with stable AP. A reduction in the serum platelet-activating factor acetylhydrolase level was associated with regression in coronary atherosclerosis, particularly the fibrous plaque volume, in patients with unstable AP.

Vascular function during prolonged progression and regression of atherosclerosis in mice

OBJECTIVE

Endothelial dysfunction is associated with atherosclerosis in mice, but it is difficult to reduce cholesterol levels enough to study regression of atherosclerosis in genetically modified mice. The goal of this study was to examine vascular structure and function before and after reducing elevated plasma lipid levels with a genetic switch in Reversa mice, and identify novel mechanisms contributing to structural and functional improvements in the vasculature after reduction of blood lipids.

METHODS AND RESULTS

After 6 months of hypercholesterolemia, endothelial function (maximum relaxation to acetylcholine) in aorta was impaired and responses to nitric oxide were unaffected. Further impairment in endothelial function was observed after 12 months of hypercholesterolemia and was associated with reductions in sensitivity to nitric oxide. Expression of dihydrofolate reductase was reduced at 6 and 12 months, and addition of the tetrahydrobiopterin precursor sepiapterin significantly improved endothelial function. Reducing cholesterol levels at 6 months normalized dihydrofolate reductase expression and prevented further impairment in endothelial function. Similar functional changes were observed after 12 months of hypercholesterolemia followed by 2 months of lipid lowering.

CONCLUSIONS

Our data suggest that endothelial dysfunction after prolonged hypercholesterolemia is the result of both impairment of sensitivity to nitric oxide and reduced nitric oxide synthase cofactor bioavailability. Both of these changes can be prevented by normalizing blood lipids during moderately severe or advanced atherosclerosis.

Progression of vascular calcification is increased with statin use in the Veterans Affairs Diabetes Trial (VADT)

OBJECTIVE

To determine the effect of statin use on progression of vascular calcification in type 2 diabetes (T2DM).

RESEARCH DESIGN AND METHODS

Progression of coronary artery calcification (CAC) and abdominal aortic artery calcification (AAC) was assessed according to the frequency of statin use in 197 participants with T2DM.

RESULTS

After adjustment for baseline CAC and other confounders, progression of CAC was significantly higher in more frequent statin users than in less frequent users (mean ± SE, 8.2 ± 0.5 mm(3) vs. 4.2 ± 1.1 mm(3); P < 0.01). AAC progression was in general not significantly increased with more frequent statin use; in a subgroup of participants initially not receiving statins, however, progression of both CAC and AAC was significantly increased in frequent statin users.

CONCLUSIONS

More frequent statin use is associated with accelerated CAC in T2DM patients with advanced atherosclerosis.

The prevention and regression of atherosclerotic plaques: emerging treatments

Occlusive vascular diseases, such as sudden coronary syndromes, stroke, and peripheral arterial disease, are a huge burden on the health care systems of developed and developing countries. Tremendous advances have been made over the last few decades in the diagnosis and treatment of atherosclerotic diseases. Intravascular ultrasound has been able to provide detailed information of plaque anatomy and has been used in several studies to assess outcomes. The presence of atherosclerosis disrupts the normal protective mechanism provided by the endothelium and this mechanism has been implicated in the pathophysiology of coronary artery disease and stroke. Efforts are being put into the prevention of atherosclerosis, which has been shown to begin in childhood. This paper reviews the pathophysiology of atherosclerosis and discusses the current options available for the prevention and reversal of plaque formation.

Effect of statin therapy on the progression of coronary atherosclerosis

BACKGROUND

An increasing number of authors employing intravascular ultrasound (IVUS) and virtual histology (VH-IVUS) have investigated the effect of statin use on plaque volume (PV) and plaque composition. However, inconsistent results have been reported. Therefore, we conducted a meta-analysis to determine the appropriate regimen of statins to effectively stabilize vulnerable coronary plaques.

METHODS

Online electronic databases were carefully searched for all relevant studies. We compared mean values of PV and plaque composition between baseline and follow-up in patients receiving statin therapy. We pooled treatment effects and calculated mean differences (MD) with the 95% confidence interval (CI) using a random-effects model. By stratified analyses, we explored the influence of clinical presentation, dose and duration of statin treatment, and low-density lipoprotein-cholesterol (LDL-C) levels on the effects of statins.

RESULTS

Seventeen studies involving 2,171 patients were analyzed. Statin therapy significantly decreased PV (-5.3 mm(3); 95% CI: -3.3 mm(3) to -7.2 mm(3) P < 0.001), without heterogeneity. When considering the dose and duration of statins used, only subgroups employing a high dose and long duration demonstrated a significant reduction in PV (p < 0.001). A significant decrease in PV was noted if achieved LDL-C levels were <100 mg/dL (p < 0.001). Statin treatment could induce a twofold decrease in PV in patients with acute coronary syndrome (ACS) compared with that observed in patients with stable angina pectoris (SAP). A regressive trend was seen for necrotic core volume (MD: -2.1 mm(3); 95% CI: -4.7 mm(3) to 0.5 mm(3), P = 0.11). However, statin use did not induce a significant change for fibrotic, fibro-fatty, or dense calcium compositions.

CONCLUSIONS

Our meta-analysis demonstrated that statin therapy (especially that involving a high dose and long duration and achieving <100 mg/dL LDL-C levels) can significantly decrease PV in patients with SAP or ACS. These data suggested that statins can be used to reduce the atheroma burden for secondary prevention by appropriately selecting the statin regimen. No significant change in plaque composition was seen after statin therapy.

Normal vascular function as a prerequisite for the absence of coronary calcification in patients free of cardiovascular disease and diabetes

BACKGROUND

The absence of coronary artery calcium (CAC) is a marker of very low cardiovascular risk. Endothelial cells may have an effect on the initiation and propagation of arterial calcification. We aimed to identify the relationship between the absence of CAC and endothelial function in individuals without cardiovascular disease and diabetes.

METHODS AND RESULTS

CAC was assessed using electron-beam computed tomography and the calcium score was then computed. Endothelial function was measured by assessing reactive hyperemia-induced vasodilation and expressed by the reactive hyperemia index (RHI). Of 82 patients, 39 had non-detectable calcium (CAC score=0) and 43 had a CAC score >0. In the CAC score=0 group, the prevalence of normal endothelial function was 84.6%, compared to 48.8% in the CAC score >0 group, P=0.001. The absence of CAC was highly correlated with normal endothelial function (γ=0.704, P<0.001). On average, endothelial function was significantly better in the CAC score=0 group than in the CAC score >0 group (RHI 2.2±0.6 vs. 1.8±0.5, P=0.002). In a multivariate logistic regression model, only normal endothelial function (odds ratio [OR] 5.03, 95% confidence interval [CI] 1.55-16.27, P=0.007) and age (years) (OR 0.91, 95% CI 0.86-0.96, P=0.002) were independently associated with the absence of CAC.

CONCLUSIONS

Normal functional status of the vasculature may be important for the prevention of coronary calcification and may partly account for the low cardiovascular risk of absent CAC.