Effect of pravastatin on progression and regression of coronary atherosclerosis and vessel wall changes in carotid and femoral arteries: a report from the Regression Growth Evaluation Statin Study

Pravastatin for lowering lipids

BACKGROUND

A detailed summary and meta-analysis of the dose-related effect of pravastatin on lipids is not available.

OBJECTIVES

Primary objective To assess the pharmacology of pravastatin by characterizing the dose-related effect and variability of the effect of pravastatin on the surrogate marker: low-density lipoprotein (LDL cholesterol). The effect of pravastatin on morbidity and mortality is not the objective of this systematic review. Secondary objectives • To assess the dose-related effect and variability of effect of pravastatin on the following surrogate markers: total cholesterol; high-density lipoprotein (HDL cholesterol); and triglycerides. • To assess the effect of pravastatin on withdrawals due to adverse effects.

SEARCH METHODS

The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials (RCTs) up to September 2021: CENTRAL (2021, Issue 8), Ovid MEDLINE, Ovid Embase, Bireme LILACS, the WHO International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also contacted authors of relevant papers regarding further published and unpublished work. The searches had no language restrictions.

SELECTION CRITERIA

Randomized placebo-controlled trials evaluating the dose response of different fixed doses of pravastatin on blood lipids over a duration of three to 12 weeks in participants of any age with and without evidence of cardiovascular disease.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility criteria for studies to be included, and extracted data. We entered lipid data from placebo-controlled trials into Review Manager 5 as continuous data and withdrawal due to adverse effects (WDAEs) data as dichotomous data. We searched for WDAEs information from all trials. We assessed all trials using Cochrane's risk of bias tool under the categories of sequence generation, allocation concealment, blinding, incomplete outcome data, selective reporting, and other potential biases.

MAIN RESULTS

Sixty-four RCTs evaluated the dose-related efficacy of pravastatin in 9771 participants. The participants were of any age, with and without evidence of cardiovascular disease, and pravastatin effects were studied within a treatment period of three to 12 weeks. Log dose-response data over the doses of 5 mg to 160 mg revealed strong linear dose-related effects on blood total cholesterol and LDL cholesterol, and a weak linear dose-related effect on blood triglycerides. There was no dose-related effect of pravastatin on blood HDL cholesterol. Pravastatin 10 mg/day to 80 mg/day reduced LDL cholesterol by 21.7% to 31.9%, total cholesterol by 16.1% to 23.3%,and triglycerides by 5.8% to 20.0%. The certainty of evidence for these effects was judged to be moderate to high. For every two-fold dose increase there was a 3.4% (95% confidence interval (CI) 2.2 to 4.6) decrease in blood LDL cholesterol. This represented a dose-response slope that was less than the other studied statins: atorvastatin, rosuvastatin, fluvastatin, pitavastatin and cerivastatin. From other systematic reviews we conducted on statins for its effect to reduce LDL cholesterol, pravastatin is similar to fluvastatin, but has a decreased effect compared to atorvastatin, rosuvastatin, pitavastatin and cerivastatin. The effect of pravastatin compared to placebo on WADES has a risk ratio (RR) of 0.81 (95% CI 0.63 to 1.03). The certainty of evidence was judged to be very low.

AUTHORS' CONCLUSIONS

Pravastatin lowers blood total cholesterol, LDL cholesterol and triglyceride in a dose-dependent linear fashion. This review did not provide a good estimate of the incidence of harms associated with pravastatin because of the lack of reporting of adverse effects in 48.4% of the randomized placebo-controlled trials.

Statins and Peripheral Arterial Disease: A Narrative Review

Peripheral arterial disease (PAD) is a highly prevalent atherosclerotic condition. In patients with PAD, the presence of intermittent claudication leads to a deterioration in quality of life. In addition, even in asymptomatic cases, patients with PAD are at high risk of cardiac or cerebrovascular events. Treatment of PAD is based on lifestyle modifications; regular exercise; smoking cessation; and control of cardiovascular risk factors, including hypercholesterolemia. A growing number of studies have shown that statins reduce cardiovascular risk and improve symptoms associated with PAD. Current guidelines recommend the use of statins in all patients with PAD in order to decrease cardiovascular events and mortality. However, the prescribing of statins in patients with PAD is lower than in those with coronary heart disease. This review provides relevant information from the literature that supports the use of statins in patients with PAD and shows their potential benefit in decreasing lower limb complications as well as cardiovascular morbidity and mortality.

Clinical Significance of Carotid Intima-Media Complex and Carotid Plaque Assessment by Ultrasound for the Prediction of Adverse Cardiovascular Events in Primary and Secondary Care Patients

Recently published recommendations from the American Society of Echocardiography on 'Carotid Arterial Plaque Assessment by Ultrasound for the Characterization of Atherosclerosis and Evaluation of Cardiovascular Risk' provoked discussion once more on the potential clinical applications of carotid intima-media complex thickness (CIMT) and carotid plaque assessment in the context of cardiovascular risk in both primary and secondary care patients. This review paper addresses key issues and milestones regarding indications, assessment, technical aspects, recommendations, and interpretations of CIMT and carotid plaque findings. We discuss lacks of evidence, limitations, and possible future directions.

Carotid Intima-Media Thickness Progression as Surrogate Marker for Cardiovascular Risk: Meta-Analysis of 119 Clinical Trials Involving 100 667 Patients

BACKGROUND

To quantify the association between effects of interventions on carotid intima-media thickness (cIMT) progression and their effects on cardiovascular disease (CVD) risk.

METHODS

We systematically collated data from randomized, controlled trials. cIMT was assessed as the mean value at the common-carotid-artery; if unavailable, the maximum value at the common-carotid-artery or other cIMT measures were used. The primary outcome was a combined CVD end point defined as myocardial infarction, stroke, revascularization procedures, or fatal CVD. We estimated intervention effects on cIMT progression and incident CVD for each trial, before relating the 2 using a Bayesian meta-regression approach.

RESULTS

We analyzed data of 119 randomized, controlled trials involving 100 667 patients (mean age 62 years, 42% female). Over an average follow-up of 3.7 years, 12 038 patients developed the combined CVD end point. Across all interventions, each 10 μm/y reduction of cIMT progression resulted in a relative risk for CVD of 0.91 (95% Credible Interval, 0.87-0.94), with an additional relative risk for CVD of 0.92 (0.87-0.97) being achieved independent of cIMT progression. Taken together, we estimated that interventions reducing cIMT progression by 10, 20, 30, or 40 μm/y would yield relative risks of 0.84 (0.75-0.93), 0.76 (0.67-0.85), 0.69 (0.59-0.79), or 0.63 (0.52-0.74), respectively. Results were similar when grouping trials by type of intervention, time of conduct, time to ultrasound follow-up, availability of individual-participant data, primary versus secondary prevention trials, type of cIMT measurement, and proportion of female patients.

CONCLUSIONS

The extent of intervention effects on cIMT progression predicted the degree of CVD risk reduction. This provides a missing link supporting the usefulness of cIMT progression as a surrogate marker for CVD risk in clinical trials.

Comparative effects of lipid lowering, hypoglycemic, antihypertensive and antiplatelet medications on carotid artery intima-media thickness progression: a network meta-analysis

Background

Carotid artery intima-media thickness (cIMT) progression is a surrogate marker of atherosclerosis with a high predictive value for future CVD risk. This study evaluates the comparative efficacies of lipid lowering, hypoglycemic, antihypertensive and antiplatelet medications on cIMT progression.

Methods

We conducted a network meta-analysis (NMA) to evaluate the relative efficacies of several drug classes in modifying cIMT progression. After a literature search in several electronic databases, studies were selected by following predetermined eligibility criteria. An inverse variance-heterogeneity model was used for NMA. Sensitivity analyses were performed to check the reliability of the overall NMA, and transitivity analyses were performed to examine the effects of modifiers on the NMA outcomes.

Results

Data were taken from 47 studies (15,721 patients; age: 60.2 years [95% confidence interval (CI) 58.8, 61.6]; BMI: 27.2 kg/m² [95% CI 26.4, 28.0]; and gender: 58.3% males [95% CI 48.3, 68.3]). Treatment duration was 25.8 months [95% CI 22.9, 28.7]. Of the 13 drug classes in the network, treatment with phosphodiesterase III inhibitors was the most effective in retarding annual mean cIMT against network placebo (weighted mean difference (WMD) − 0.059 mm [95% CI − 0.099, − 0.020) followed by the calcium channel blockers (WMD − 0.055 mm [95% CI − 0.099, 0.001]) and platelet adenosine diphosphate inhibitors (WMD − 0.033 mm [95% CI − 0.058, 0.008]). These 3 drug classes also attained the same positions when the NMA was conducted by using first-year changes in mean cIMT. In transitivity analyses, longer treatment duration, higher body mass index (BMI), and a higher baseline cIMT were found to be independently associated with a lesser reduction in annual mean cIMT. However, in a multivariate analysis with these 3 modifiers, none of these factors was significantly associated with annual change in mean cIMT. In the placebo group, age was inversely associated with annual change in mean cIMT independently.

Conclusion

Phosphodiesterase III inhibitors and calcium channel blockers are found more effective than other drug classes in retarding cIMT progression. Age, BMI, and baseline cIMT may have some impact on these outcomes.

Electronic supplementary material

The online version of this article (10.1186/s12933-019-0817-1) contains supplementary material, which is available to authorized users.

The challenges of treating peripheral arterial disease

Today, peripheral arterial disease (PAD) patients need effective medical care for an extended period of their lifetime. Therefore, different treatment modalities have to be tied sequentially into an effective therapeutic chain. First, preventive measures have to be reinforced and risk factors tightly controlled. Furthermore, antiplatelet agents have to be applied in every PAD patient to reduce the risk of cardiac and cerebral ischemic events, restenosis or reocclusion after revascularization, and possibly also progression of the PAD itself. Angiotensin-converting enzyme (ACE) inhibitors should be entertained in high-risk groups such as PAD patients with diabetes. In the claudicant, exercise therapy should be strongly encouraged and vasoactive drugs considered for those who are not good candidates for either exercise training or revascularization. In patients with disabling claudication or critical limb ischemia, revascularization procedures are highly effective. Especially for high-grade stenoses or short arterial occlusions, percutaneous transluminal angioplasty (PTA) should be the method of fi rst choice followed by the best surgical procedure later on. To achieve good long-term effi cacy, a close follow-up including objective tests of both the arterial lesion and hemodynamic status, surveillance of secondary preventive measures and risk factor control is mandatory.

Multiterritory Atherosclerosis and Carotid Intima-Media Thickness as Cardiovascular Risk Predictors After Percutaneous Angioplasty of Symptomatic Subclavian Artery Stenosis

OBJECTIVES

To identify independent predictors of cardiovascular events among patients with subclavian artery stenosis.

METHODS

Two hundred eighteen consecutive patients with subclavian artery stenosis referred to angioplasty were examined for coexistent coronary, renal, or lower extremity artery stenosis of 50% or greater. Initial carotid intima-media thickness and internal carotid artery (ICA) stenosis were assessed. Intima-media thickness was reassessed in 108 randomly chosen patients to evaluate the change over time. The incidence of cardiovascular death, myocardial infarction (MI), ischemic stroke, and symptomatic lesion progression was recorded.

RESULTS

The patients included 116 men and 102 women (mean age ± SD, 62.1 ± 8.4 years). Isolated subclavian artery stenosis and involvement of 1, 2, and 3 or 4 other territories with stenosis of 50% or greater were found in 46 (21.1%), 83 (38.1%), 55 (25.2%), and 34 (15.6%) patients, respectively. Internal carotid artery stenosis of 50% or greater (relative risk [RR], 1.54; 95% confidence interval [CI], 1.39-1.70; P < .001) and initial intima-media thickness (RR, 1.16; 95% CI, 1.05-1.28; P = .005) were identified as independent markers of multiterritory atherosclerosis. The optimal intima-media thickness cutoff for atherosclerosis extent was 1.3 mm (sensitivity, 75.6%; specificity, 76.1%). During follow-up of 57 ± 35 months, cardiovascular death, MI, and ischemic stroke occurred in 29 patients (13.3%). Those patients had significantly higher intima-media thickness progression (+0.199 ± 0.57 versus +0.008 ± 0.26 mm; P = .039) and more widespread initial atherosclerosis (mean territories, 1.8 ± 1.1 versus 1.3 ± 1.1; P = .042). Independent predictors of cardiovascular death, MI, ischemic stroke, and lesion progression were coronary artery disease (RR, 1.32; 95% CI, 1.10-1.58; P = .003) and intima-media thickness progression (RR, 1.22; 95% CI, 1.02-1.46; P = .033; sensitivity, 75.0%; specificity, 61.8%).

CONCLUSIONS

In patients with symptomatic subclavian artery stenosis, baseline carotid intima-media thickness and ICA stenosis of 50% or greater are associated with multiterritory atherosclerosis, whereas intima-media thickness progression is associated with the risk of cardiovascular events.

All cholesterol-lowering interventions are expected to reduce stroke: Confirmatory data from IMPROVE-IT

The relationship of cholesterol with stroke is much less clear than its relationship with myocardial infarction, thus confounding the interpretation of results with cholesterol-lowering trials (Di Napoli et al., 2002) [1], (De Caterina et al., 2010) [2]). IMPROVE-IT data ((Cannon et al. 2015) [3]), showing a 13.3% reduction in total cholesterol at one year in association with a hazard ratio (HR) of 0.i86 for total stroke during the trial, are very closely aligned with the relative risk of 0.90 predicted based on the totality of lipid lowering interventions ((De Caterina et al., 2016) [4]). We here provide the data from the original trials used to construct this meta-analysis, with the now added additional data from IMPROVE-IT, well-fitting the previously found meta-regression line. These data are important to predict stroke outcomes in currently ongoing trials now testing PCSK9 or cholesterol ester transfer protein inhibitors.

Carotid artery intima-media thickness and the renin-angiotensin system

Carotid artery intima-media thickness (IMT) is a biomarker for cardiovascular disease that also predicts the risk of cardiovascular mortality. Angiotensin-converting enzyme (ACE) inhibition is a unique therapeutic modality because it both treats hypertension and improves arterial health and cardiovascular disease outcomes. Controversy exists regarding the role of ACE inhibitors and angiotensin receptor blockers (ARBs) in IMT regression. Our article provides an update on how ACE inhibitors and ARBs could play a role in decreasing IMT.

Carotid intima-media thickness studies: study design and data analysis

BACKGROUND

Carotid intima-media thickness (CIMT) measurements have been widely used as primary endpoint in studies into the effects of new interventions as alternative for cardiovascular morbidity and mortality. There are no accepted standards on the use of CIMT measurements in intervention studies and choices in the design and analysis of a CIMT study are generally based on experience and expert opinion. In the present review, we provide an overview of the current evidence on several aspects in the design and analysis of a CIMT study on the early effects of new interventions.

SUMMARY OF ISSUES

A balanced evaluation of the carotid segments, carotid walls, and image view to be used as CIMT study endpoint; the reading method (manual or semi-automated and continuously or in batch) to be employed, the required sample size, and the frequency of ultrasound examinations is provided. We also discuss the preferred methods to analyse longitudinal CIMT data and address the possible impact of, and methods to deal with missing and biologically implausible CIMT values.

CONCLUSIONS

Linear mixed effects models are the preferred way to analyse CIMT data and do appropriately handle missing and biologically implausible CIMT values. Furthermore, we recommend to use extensive CIMT designs that measure CIMT at regular points during the multiple carotid sites as such approach is likely to increase the success rates of CIMT intervention studies designed to evaluate the effects of new interventions on atherosclerotic burden.

Use of statins in lower extremity artery disease: a review

Background

Lower extremity artery disease (LE-PAD) is one of the most common manifestations of atherosclerosis, particularly in elderly patients, and it is related to a high cardiovascular risk.

Description

It is well established that statin therapy is characterized by crucial benefits on cardiovascular system by limiting atherosclerotic progression and reducing cardiovascular events and mortality. A growing body of evidence support efficacy of statins in LE-PAD due to the ability of both reducing cardiovascular risk and improving walking distance and, hence, quality of life. Consequently, statin therapy should be considered in all LE-PAD patients and new LDL-cholesterol targets should be reached.

Conclusions

Our opinion is that statin therapy remains still underutilized or with inadequate dosage, so therapy of LE-PAD patients should be improved to obtain all the demonstrated benefits of statins.

Non-invasive imaging of atherosclerosis

Atherosclerosis is an inflammatory disease that causes most myocardial infarctions, strokes, and acute coronary syndromes. Despite the identification of multiple risk factors and widespread use of drug therapies, it still remains a global health concern with associated costs. It is well known that the risks of atherosclerotic plaque rupture are not well correlated with stenosis severity. Lumenography has a central place for defining the site and severity of vascular stenosis as a prelude to intervention for relief of symptoms due to blood flow limitation. Atherosclerosis develops within the arterial wall; this is not imaged by lumenography and hence it provides no information regarding underlying processes that may lead to plaque rupture. For this, we must rely on other imaging modalities such as ultrasound, computed tomography, magnetic resonance imaging, and nuclear imaging methods. These are capable of reporting on the underlying pathology, in particular the presence of inflammation, calcification, neovascularization, and intraplaque haemorrhage. Additionally, non-invasive imaging can now be used to track the effect of anti-atherosclerosis therapy. Each modality alone has positives and negatives and this review will highlight these, as well as speculating on future developments in this area.

Effect of number of ultrasound examinations on the assessment of carotid intima-media thickness changes over time: the example of the METEOR study

OBJECTIVE

To evaluate the effect of the number and positioning during follow-up of ultrasound examinations on the rate of change in carotid intima-media thickness (CIMT) using METEOR (Measuring Effects on Intima-Media Thickness: an Evaluation of Rosuvastatin) as an example.

METHODS

METEOR was a randomized, placebo-controlled trial showing that rosuvastatin reduced progression of 2-year change in CIMT among low-risk patients with subclinical atherosclerosis. In the full METEOR protocol, ultrasound examinations were performed twice before randomization, once each at 6, 12, and 18 months after randomization, and then twice at the end of study at 24 months. For the present study, 17 study designs were retrospectively constructed with varying number and position of ultrasound examinations during the study. Differences in the rate of change in maximum CIMT between these study designs were compared.

RESULTS

Variations in frequency of ultrasound visits gave results in the same direction and magnitude for the change in maximum CIMT for both groups (i.e. nonsignificant change for rosuvastatin and significant progression for placebo, and a significant difference between treatments). However, standard errors were larger when the number of exams reduced. This finding was consistent over different lengths of follow-up, sample sizes, and with CIMT measurements made on different locations.

CONCLUSION

Protocols with different number and timing of ultrasound examinations minimally affect the direction and magnitude of treatment effects on the rate of change in CIMT. However, reductions in exam frequency increase standard errors of rates of change, suggesting larger sample sizes would be required to have the same level of statistical power.

Imaging of atherosclerosis

It is now well recognized that the atherosclerotic plaques responsible for thrombus formation are not necessarily those that impinge most on the lumen of the vessel. Nevertheless, clinical investigations for atherosclerosis still focus on quantifying the degree of stenosis caused by plaques. Many of the features associated with a high-risk plaque, including a thin fibrous cap, large necrotic core, macrophage infiltration, neovascularization, and intraplaque hemorrhage, can now be probed by novel imaging techniques. Each technique has its own strengths and drawbacks. In this article, we review the various imaging modalities used for the evaluation and quantification of atherosclerosis.

Are changes in carotid intima-media thickness related to risk of nonfatal myocardial infarction? A critical review and meta-regression analysis

BACKGROUND

Carotid intima-media thickness (CIMT) is increasingly being used as a surrogate end point in randomized control trials (RCTs) of novel cardiovascular therapies. However, it remains unclear whether changes in CIMT that result from these therapies correlate with nonfatal myocardial infarction (MI).

METHODS

We performed a literature search of RCTs from 1990-2009 that used CIMT. Eligible RCTs (1) included quantitative and sequential assessments in CIMT at least 1 year apart and (2) reported nonfatal MI. Across RCTs, random-effects metaregression was employed to correlate differences in mean change in CIMT between treatment and control groups over time with the log odds ratios of developing nonfatal MI during follow-up.

RESULTS

Overall, we identified 28 RCTs with 15,598 patients. Differences in mean change in CIMT over time between treatment and control groups correlated with developing nonfatal MI during follow-up: for each 0.01 mm per year smaller rate of change in CIMT, the odds ratio for MI was 0.82 (95% CI, 0.69 to 0.96; P = .018). Results were similar in subgroups of RCTs with >1 year follow-up (P = .018) and those with at least 50 subjects in the treatment group (P = .019). However, there was no significant relationship between mean change in CIMT and nonfatal MI in RCTs evaluating statin therapy or those with high CIMTs at baseline (P > .20 in both instances).

CONCLUSIONS

Less progression in CIMT over time is associated with a lower likelihood of nonfatal MI in selected RCTs; however, these findings were inconsistent at times, suggesting caution in using CIMT as a surrogate end point.

Imaging biomarkers of atherosclerosis

Atherosclerosis imaging plays a significant role in an understanding of the natural history of vascular disease and is increasingly used to assess the efficacy of novel therapeutics. Furthermore, the concepts of 'vulnerable plaque' and, more recently, of 'vulnerable patient' have driven cardiovascular imaging technologies to develop methods for expanded qualitative and quantitative analyses. Indeed, developmental efforts are underway to better demonstrate thin fibrous cap and large necrotic cores, and to determine the correlation between these findings and subsequent cardiovascular events. In this article, we consider a wide variety of cardiovascular imaging techniques that are used as biomarkers of atherosclerosis. These technologies include traditional imaging such as angiography, as well as advanced imaging techniques using both invasive and noninvasive approaches.

Genetic variation in 3-hydroxy-3-methylglutaryl CoA reductase modifies the chemopreventive activity of statins for colorectal cancer

Genetic variation in 3-hydroxy-3-methylglutaryl CoA reductase (HMGCR), the rate-limiting enzyme in cholesterol synthesis, modifies the effect of statins on serum cholesterol levels. Long-term use of statins is associated with a reduced risk of colorectal cancer (CRC) in some, but not all, studies. We genotyped variants in 40 candidate genes important for cholesterol synthesis and metabolism in a population-based case-control study of CRC involving 2,138 incident cases and 2,049 population-based controls. We identified a single-nucleotide polymorphism in the HMGCR gene that significantly modified the protective association between statins and CRC risk. Compared with nonusers, the unadjusted odds ratio of CRC among statin users with the A/A genotype of rs12654264 in HMGCR was 0.3 (95% confidence interval, 0.18-0.51) and among statin users with the T/T genotype was 0.66 (95% confidence interval, 0.41-1.06; P-interaction = 0.0012). This genetic variant (A/A genotype of rs12654264) also was associated with lower serum levels of low-density lipoprotein among all cases and controls. In colon cancer cell lines, the reduction in cholesterol levels after statin treatment was substantially stronger in cells carrying the A/A genotype, and this difference was related to alternative splicing involving the HMGCR statin-binding domain. We anticipate that these data may advance the development of personalized statin use for reducing the risk of cancer as well as cardiovascular disease among the approximately 25 million people currently using statins worldwide.

The JUPITER and AURORA clinical trials for rosuvastatin in special primary prevention populations: perspectives, outcomes, and consequences

Statins have emerged at the forefront of preventive cardiology and have significantly reduced cardiovascular events and mortality. Nonetheless, cardiovascular disease remains the leading cause of death in the United States and in other developed countries, as well as the etiology of significant morbidity and health-care expenditure. In an attempt to reduce potentially missed opportunities for instituting preventive therapy, the JUPITER study (Justification for the Use of Statins in Prevention: an Intervention Trial Evaluating Rosuvastatin) and the AURORA study (A Study to Evaluate the Use of Rosuvastatin in Subjects on Regular Hemodialysis: An Assessment of Survival and Cardiovascular Events) examined the effect of statins in two specific patient populations who currently do not meet the guidelines for statin treatment, but nonetheless, are at high cardiovascular risk. This review outlines the JUPITER and AURORA trials, interprets the data and significance of the results, analyses the drawbacks and impact of both trials and delineates the potential for further clinical trials.

Pharmacogenomics of Colorectal Cancer Prevention and Treatment

Pharmacogenomic tools are beginning to emerge that will provide guidance in the treatment and prevention of colorectal cancer. Significant individual genetic variation exists in drug metabolism of 5FU, capecitabine, irinotecan, and oxaliplatin that influences both the toxicity and efficacy of these agents. Recent FDA approval of genetic testing for mutations in the UGT1A1 gene that predict adverse reactions to irinotecan is ushering in a new era that will increasingly rely on genotyping to individualize treatment decisions for patients with cancer as well as for patients at high risk who may be candidates for chemoprevention agents. This review focuses on current knowledge regarding key mutations and polymorphisms which affect outcomes for colorectal cancer patients, as well as the pharmacogenetics of chemoprevention trials.

Intensive lipid lowering may reduce progression of carotid atherosclerosis within 12 months of treatment: the METEOR study

BACKGROUND

In several statin trials, vascular event rates for treatment groups begin to separate 1 year after commencement of treatment. For atherosclerosis progression, the temporal sequence of the effect has not been defined. We used data from the Measuring Effects on intima media Thickness: an Evaluation Of Rosuvastatin (METEOR) trial to determine the earliest time point at which significant differences in atherosclerosis progression rates could be detected after initiation of statin therapy.

METHODS

The METEOR trial was a double-blind, randomized placebo-controlled trial that studied the effect of LDL-C lowering with 40 mg rosuvastatin on the rate of change of carotid intima media thickness (CIMT) measured by B-mode ultrasound amongst 984 low risk subjects. Ultrasound assessments were made at baseline and every 6 months up to 2 years.

RESULTS

Rosuvastatin treatment was associated with a 49% reduction in LDL-C-C, a 34% reduction in total cholesterol, an 8.0% increase in HDL-C and a 16% reduction in triglycerides (all P < 0.0001 compared with placebo). The difference in rate of mean maximum CIMT progression between the rosuvastatin and placebo groups (based on near and far wall measurements from both left and right common carotid and internal carotid segments and carotid bifurcation) was not statistically significant after 6 months (0.0023 mm year(-1) and 0.0106 mm year(-1), respectively P = 0.34). After 12 months, CIMT progression rates were significantly different between the groups: 0.0032 mm year(-1) and 0.0133 mm year(-1) in the rosuvastatin-treated and placebo-treated groups, respectively (P = 0.049). This divergence grew with further follow-up: -0.0009 mm year(-1) and 0.0131 mm year(-1) after 18 months (P < 0.001) and -0.0014 mm year(-1) and 0.0131 mm year(-1) after 24 months of treatment (P < 0.001). Results were stronger for the mean common CIMT progression (based on near and far wall measurements from both left and right common carotid segments).

CONCLUSION

Aggressive LDL-C lowering seems to exert its beneficial effect on atherosclerosis progression during the first 12 months of treatment. This parallels the timing of event reduction seen in clinical trials and suggests that the efficacy of lipid lowering treatment on CIMT progression can be evaluated in trials with a duration of 1 year, given sufficient sample size, high precision of measurements and a treatment effect comparable to that seen in METEOR.

The Effects of Statins on the Progression of Atherosclerotic Renovascular Disease

BACKGROUND/AIMS

The aim was to examine the influence of statin therapy on the natural history of atherosclerotic renal artery stenosis (RAS).

METHODS

Our hospital atherosclerotic renovascular disease (ARVD) database was analysed for patients who underwent repeat renal angiography during clinical follow-up. Patients with >or=1 RAS lesion and >or=4 months between baseline and repeat renal angiography were analysed. 79 patients were included. Baseline renal arterial anatomy was classified as normal, <or=50% RAS, >50% RAS or renal artery occlusion.

RESULTS

Mean follow-up time between angiograms was 27.8 +/- 22.3 (4.0-101.9) months. Progression of RAS occurred in 28 (23%) vessels, regression in 14 (12%) and no significant change in 79 (65%). Multivariate regression analysis showed that baseline proteinuria >0.6 g/day increased the risk of progressive disease (relative risk, RR, 3.8; 95% confidence interval, CI, 1.2-12.1), treatment with statin reduced the risk of progression (RR 0.28; 95% CI 0.10-0.77). 14 renal arteries from 12 patients showed RAS regression with a greater proportion on statin [statin treatment 10 (83%) versus no statin treatment 2 (17%), p = 0.001]. Change in estimated glomerular filtration rate (eGFR) per year was not different between statin- and no-statin-treated groups.

CONCLUSIONS

Progression or development of RAS was significantly less likely to occur with statin therapy. Delta eGFR did not correlate with progression of RAS, reflecting the importance of intrarenal injury in the aetiology of renal dysfunction. Our results suggest statin therapy can alter the natural history of ARVD.

Design and Rationale of the ARBITER 6 Trial (Arterial Biology for the Investigation of the Treatment Effects of Reducing Cholesterol)-6-HDL and LDL Treatment Strategies in Atherosclerosis (HALTS)

BACKGROUND

Recent evidence on the use of statin therapy indicates the potential for ultra-low levels of LDL-C to provide greater protection from recurrent coronary heart disease events. Guidelines for the treatment of lipid disorders were revised to indicate that an LDL-C treatment goal of 70 mg/dl was optional (NCEP ATPIII). In these same guidelines, low levels of HDL-C are also suggested but not specifically proscribed as a target of therapy. Recently ARBITER 2 (Arterial Biology for the Investigation of the Treatment Effects of Reducing Cholesterol 2) has provided the first evidence of the potential of raising HDL-C with extended release niacin when added to statin monotherapy in secondary prevention. However, whether this approach would be superior to a strategy in which lower concentrations of LDL-C are targeted is unknown.

MATERIALS AND METHODS

ARBITER 6-HALTS ( HDL and LDL Treatment Strategies) will be a randomized, parallel group, open-label study comparing HDL-C and LDL-C focused strategies of lipid treatments for their effects on atherosclerosis. Up to 400 subjects will be assigned to either intensified LDL-C lowering therapy with ezetimibe or HDL-C raising therapy with extended-release niacin. The primary endpoint is the mean change in the intima-media thickness of the common carotid artery after 14 months. Secondary endpoints include the change in lipid values and lipid subfractions, drug discontinuation due to adverse effects, change in quality of life, and a composite endpoint consisting of all major adverse cardiovascular events.

CONCLUSION

ARBITER 6-HALTS will guide clinicians on whether a lipid treatment strategy of raising HDL-C or further LDL-C reduction is superior in the secondary prevention of coronary heart disease.

What are SNPs and haplotypes and how will they help us manage the prevention of adult cancer?

Human genetic variation data are now publicly available on a large scale, from public and private discovery efforts. Datasets from the International Haplotype Map Consortium and Perlegen Sciences provide a level of knowledge about human genetic variation that is unprecedented. In combination with novel high-throughput genotyping technologies, these new resources will allow cancer prevention investigators to identify in a more precise way which genetic subsets of patients are likely to benefit most from chemoprevention and screening interventions.

Medical management of peripheral arterial disease

Whether symptomatic or not, peripheral arterial disease (PAD), atherosclerosis in the arteries of the lower extremities, is a common disorder in the general population. The prevalence increases with age and under the influence of vascular risk factors. The most classic symptomatic expression of PAD is intermittent claudication. However, the majority of patients with PAD is asymptomatic or has leg symptoms other than classic intermittent claudication. Both symptomatic and asymptomatic subjects with PAD have increased mortality rates, mainly due to cardiovascular and cerebrovascular expressions of atherosclerotic disease. This review focuses on the current available medical therapies for PAD, including risk-factor modification and antiplatelet therapies, as well as strategies for symptomatic relief in both patients with intermittent claudication and patients with critical limb ischemia. In general, risk factor modification and antiplatelet therapy is essential in all patients with PAD to prevent systemic atherosclerotic complications. Furthermore, for symptomatic relief exercise therapy is the main intervention while pharmacological treatment should be only complementary. In patients with critical limb ischemia, when revascularization therapy is not possible, an attempt should be made to avoid amputation with conservative treatment using analgesics, vasodilators and/or anticoagulants. In case of an acute onset of critical limb ischemia, thrombolysis is indicated.

Atherosclerotic disease regression with statins: studies using vascular markers

Vascular imaging techniques enable identification of atherosclerosis in the sub-clinical phase and allow assessment of interventions to modify disease progression. Angiography has limited utility for tracking the progression of atherosclerosis because of its invasive nature, limited sensitivity for detecting early lesions and relatively low interscan reproducibility. Intravascular ultrasound (IVUS)an electron beam computed tomography (EBCT) are more sensitive and reproducible; however, available data on their ability for tracking disease progression are few. Measurement of carotid intima media thickness (CIMT) by B-mode ultrasound is a well-validated procedure for this application. In comparison with angiography, CIMT demonstrates greater sensitivity for detecting early atherosclerosis and lipid-rich plaques that are vulnerable to rupture. Continued validation and development of imaging techniques, such as magnetic resonance imaging (MRI), will facilitate the assessment of atherosclerosis progression in intervention studies. Stains are effective low-density lipoprotein cholesterol (LDL-C) lowering agents, and imaging studies have demonstrated their ability to slow progression and promote regression of atherosclerosis. The benefits of therapy on atherosclerosis regression appear to extend to soft atherosclerotic plaques that are still developing and treatment effects are independent of baseline LDL-C level. Hence, imaging studies support early intervention with statins in coronary heart disease patients, irrespective of lipid level.

Two-year statin therapy does not alter the progression of intima-media thickness in patients with type 2 diabetes without manifest cardiovascular disease

OBJECTIVE

Cardiovascular disease (CVD) is the most important cause of mortality in patients with type 2 diabetes. We aimed to determine the effect of statin therapy versus placebo on the progression of carotid intima-media thickness (IMT) in type 2 diabetic patients without manifest CVD.

RESEARCH DESIGN AND METHODS

A randomized, placebo-controlled, double-blind clinical trial was performed in 250 patients with type 2 diabetes. Patients were given either 0.4 mg cerivastatin or placebo daily. In August 2001, when cerivastatin was withdrawn from the market, 0.4 mg cerivastatin was replaced by 20 mg simvastatin without deblinding the study. The primary end point was the change of mean common carotid IMT, as measured by B-mode ultrasound, over 2 years.

RESULTS

Common carotid IMT at baseline was 0.780 mm in the placebo group and 0.763 mm in the statin group and did not change significantly after 2 years. There was no significant difference in IMT change in any carotid segment between the groups. LDL cholesterol was reduced by 25% in the statin group and increased by 8% in the placebo group (P <0.001). Cardiovascular events occurred in 12 patients in the placebo group and two patients in the statin group (P=0.006).

CONCLUSIONS

There was no effect of 2 years' statin therapy on carotid IMT in type 2 diabetic subjects. The natural history of IMT in our patients was milder than anticipated. In contrast, we observed a significantly lower cardiovascular event rate on statin therapy. Prognostic tools other than IMT should be explored in this patient group.

Effects of statins on vascular structure and function: a systematic review

PURPOSE

Statins reduce cardiovascular events by more than can be explained by their effects on lipids. We conducted a systematic review of how statins affect vascular structure and function, differences among statins, and correlations between the effects of statins on vascular outcomes and either lipid levels or cardiovascular outcomes.

METHODS

We primarily searched MEDLINE (1980 to March 2004) to identify all studies with at least 10 subjects that reported the effects of currently available statins on coronary artery stenosis, carotid intima-media thickness, and endothelial function (excluding studies of drug combinations and subjects with organ transplants). Meta-analyses were performed when feasible.

RESULTS

Statins decrease the progression and increase the regression of coronary artery lesions and luminal narrowing. Compared with placebo, statins decrease the likelihood of coronary artery restenosis (summary risk ratio = 0.85; 95% confidence interval: 0.77 to 0.95). Statins appear to slow the progression of carotid artery intima-media thickness. Although the effect of statins on coronary endothelial function is uncertain, statins appear to improve peripheral endothelial function. There is no conclusive evidence to suggest that individual statins differ in their effects on these outcomes. Studies generally found weak or no correlation between the effects of statins on vascular outcomes and lipid levels. No study showed a correlation between vascular effect and clinical outcome.

CONCLUSION

Statins slow the progression of, and may reverse, atherosclerosis. The magnitude of these effects, however, is small compared with the effects of statins on cardiovascular events. Statins also improve measures of vascular function, which may contribute to their clinical benefits. There is insufficient evidence to suggest that individual statins differ in their vascular effects.

Role of surrogate markers in assessing patients with diabetes mellitus and the metabolic syndrome and in evaluating lipid-lowering therapy

Diabetes mellitus and the metabolic syndrome (MS) are reaching epidemic proportions in the United States, and cardiovascular disease continues to be the leading cause of death among patients with diabetes. A range of noninvasive screening tools may help reduce the morbidity and mortality of patients with diabetes because of early detection of subclinical cardiovascular disease and active monitoring of the effectiveness of therapy. Surrogate markers of subclinical disease include conventional and contrast-enhanced ultrasound imaging of carotid artery intima-media thickness (c-IMT), 2-dimensional echocardiography, coronary artery calcium imaging, cardiac magnetic resonance imaging, ankle-brachial indices, and brachial artery reactivity testing. Because these noninvasive imaging tools are relatively comfortable and entail relatively low risk to the patient, they are ideal for initial screening and for the repeated imaging that is required for monitoring the effectiveness of therapy. Moreover, when used in large numbers of patients with diabetes, prediabetes, and the MS, these imaging tools may be useful in developing and validating thresholds for the use of lipid-lowering therapy as well as clear therapeutic goals for this population. In addition, contrast-enhanced c-IMT scans now produce real-time images of the vasa vasorum and neovascularization of atherosclerotic plaque, potentially causing a paradigm shift in our view of the genesis of atherosclerosis and affecting treatment options for all populations. Thus, surrogate markers may not only help improve individual patient outcomes, they also may help direct scarce medical resources to maximize medical benefits, improve overall medical care, and minimize costs and untoward side effects.

Emerging, noninvasive surrogate markers of atherosclerosis

Noninvasive surrogate markers of atherosclerosis allow the physician to identify subclinical disease before the occurrence of adverse cardiovascular events, thereby limiting the need to perform invasive diagnostic procedures. Imaging modalities, such as carotid artery ultrasound, two-dimensional echocardiography, coronary artery calcium imaging, cardiac magnetic resonance imaging, ankle-brachial indices, brachial artery reactivity testing, and epicardial coronary flow reserve measurements, provide information that may improve the predictive value of a person's risk of developing clinically significant atherosclerotic disease. Newer imaging modalities have also emerged to bring insight into the pathophysiology and treatment of atherosclerosis.

The Osteoporosis Prevention and Arterial effects of tiboLone (OPAL) study: design and baseline characteristics

The Osteoporosis Prevention and Arterial effects of tiboLone (OPAL) trial is a three-arm, randomized, placebo-controlled, double-blind study to determine the effect of tibolone 2.5 mg (Org OD 14) and continuous combined conjugated equine estrogens plus medroxyprogesterone acetate (0.625 mg/2.5 mg respectively) on progression of intima-media thickness of the carotid arteries and bone mineral density of the lumbar vertebrae and proximal femur in postmenopausal women. A total of 866 healthy postmenopausal women were recruited in six U.S. centers and five European centers. Duplicate carotid ultrasound examinations of the common carotid artery, the carotid bifurcation, and the internal carotid artery were performed at baseline. Single measurements of bone mineral density of the lumbar vertebrae and proximal femur were obtained at baseline. After randomization, ultrasound examinations were repeated every 6 months for 36 months following baseline, with a duplicate examination at the end of the study. Bone mineral density was measured every 12 months throughout the trial. The primary outcome is change in mean common carotid intima-media thickness (CIMT), defined as the average of the intima-media thickness measurements performed circumferentially at predefined angles for the near and far wall of 10-mm segments of the right and left distal common carotid arteries. Unique new features of the OPAL study are the specifically developed OPAL ultrasound protocol, yielding highly reproducible CIMT measurements, and the use of two experienced core laboratories for CIMT readings (one in the United States and one in Europe) with one common quality assurance and control program. The OPAL study is a large, placebo-controlled trial evaluating the effects of tibolone, as well as one of the first large randomized studies to determine the effects of continuous combined estrogen-progestin therapy on carotid atherosclerosis in healthy postmenopausal women. The OPAL study results are expected to complement other studies on atherosclerosis progression in healthy postmenopausal women.

Peripheral arterial disease: medical care and prevention of complications

Peripheral arterial disease (PAD) is a common but under-recognized problem affecting older patients. Intermittent claudication is the most frequent symptom of PAD, although the diagnosis of PAD is often overlooked until the patient presents with limb-threatening ischemia. Importantly, PAD is a marker for generalized atherosclerosis and is closely associated with coronary and cerebrovascular disease. The severity of PAD has been correlated with an increased risk of myocardial infarction, stroke, and cardiovascular death. The recognition and diagnosis of PAD, combined with its appropriate medical management, may well reduce the overall risk of cardiovascular morbidity. When diagnosed early, both exercise and pharmacotherapy can ameliorate symptoms of claudication, augment functional performance, and improve quality of life.

What constitutes best medical therapy for peripheral arterial disease?

Peripheral arterial disease (PAD) is associated with a high morbidity and mortality, largely from coronary and cerebrovascular disease, which often overshadows the PAD itself. Best Medical Therapy (BMT), comprising smoking cessation, antiplatelet agent use, cholesterol reduction, exercise therapy, and the diagnosis and treatment of hypertension and diabetes mellitus; is evidenced based and can result in significant reductions in cardiovascular risk, as well as some improvement in PAD. Previous data have largely been restricted to patients with coronary artery disease, and their relevance to PAD has been extrapolated. However, data are now starting to become available, such as the Heart Protection Study, with data specific to PAD patients. This article reviews the data regarding the use of BMT in patients with PAD, and based on this, makes recommendations for the use of BMT in this group of patients.

Intermittent claudication: pharmacoeconomic and quality-of-life aspects of treatment

The purpose of this article is to review the literature on the pharmacoeconomics of treatment for intermittent claudication and to discuss the importance of quality-of-life assessment for evaluating treatment strategies. Systemic risk reduction is the primary objective in the treatment of patients with intermittent claudication, as these patients have a high future risk of cardiovascular morbidity and mortality. Modification of cardiovascular risk factors accompanied by antiplatelet therapy is likely to improve overall survival, reduce myocardial infarction and stroke, and will, perhaps, also reduce the risk of ulcers and amputation at acceptable cost-effectiveness ratios. The second goal in the treatment of patients with intermittent claudication is to improve their walking capacity and community-based functional status. Supervised exercise training is the most effective noninvasive intervention to improve walking capacity, but may have elevated indirect costs. Among patients with disabling claudication who are candidates for invasive therapeutic procedures, angioplasty is cost effective in those with femoropopliteal stenosis or occlusion and in those with critical limb ischaemia and a stenosis. For all these therapeutic strategies there is a need to relate the costs to a relevant and comprehensive measure of effectiveness. Quality-of-life evaluation by using questionnaires exploring the specific problems encountered by patients with intermittent claudication in their daily life appear to be the most appropriate tool to evaluate the net result of a treatment. Cost-utility studies by combining pecuniary and quality-of-life evaluations provide information that is extremely useful to patients with intermittent claudication, regulatory authorities, the pharmaceutical industry and healthcare providers.

Does B-mode common carotid artery intima-media thickness differ from M-model?

An increased intima-media thickness of the common carotid artery is thought to be an early sign of atherosclerosis. Both B- and M-mode ultrasonographic techniques are used to measure the intima-media thickness of the common carotid artery (B-IMT and M-IMT, respectively). The present study compares intima-media thickness of the common carotid artery measured with the two techniques. Intima-media thickness was measured in a random population sample of 250 subjects. Comparison was made by mean and 95% confidence intervals of differences between B-IMT and M-IMT, by linear regression analysis, and by intraclass and concordance correlation coefficients. M-IMT was + 0.011 +/- 0.091 mm (95% confidence intervals: -0.167 to + 0.188 mm) larger than B-IMT, which was 0.661 +/- 0.136 mm (range: 0.380 to 1.120 mm). Intraclass and concordance correlation coefficients were 0.802 and 0.801, respectively. In conclusion, acceptable agreement exists between the two methods and there was no important systematic difference between B-IMT and M-IMT.

Impact of weight reduction on early carotid atherosclerosis in obese premenopausal women

OBJECTIVE

To investigate the extent of carotid atherosclerosis and the effect of weight loss on carotid intima-media thickness (IMT) in obese premenopausal women.

RESEARCH METHODS AND PROCEDURES

In 43 obese premenopausal women who participated in a 3-month weight reduction program with a hypocaloric diet, IMT was measured by B-mode high-resolution ultrasound at entry and after 5 months of follow-up. Blood samples were analyzed at entry, after intervention, and after 5 months of follow-up. Nineteen lean women served as control subjects.

RESULTS

At entry, common carotid IMT (0.72 vs. 0.59 mm), carotid bulb IMT (0.90 vs. 0.71 mm), and overall mean IMT (0.81 vs. 0.65 mm) were greater in obese women than in lean women (all p < 0.01). After dietary intervention decreases in blood pressure, low density lipoprotein to high density lipoprotein cholesterol ratio, triglycerides, fibrinogen, plasminogen activator inhibitor-1, and an increase in tissue-type plasminogen activator activity levels were observed. These effects persisted after follow-up in 14 women who maintained reduced weight. Reduction in carotid bulb IMT (to 0.81 mm, p < 0.01) and overall mean IMT (to 0.79 mm, p < 0.05) was observed in this subgroup. No significant change of carotid IMT was detected in eight women who regained weight. Changes in IMT were associated independently and significantly with changes in body mass index, low density lipoprotein to high density lipoprotein cholesterol ratio, and plasminogen activator inhibitor-1 antigen.

DISCUSSION

Obese premenopausal women had greater IMT than did age-matched lean controls. It seems that this early atherosclerotic changes may be reversed by normalization of body weight.

The future of obesity research

As endocrinologists, we view better treatment as the goal of obesity research. The ideal obesity treatment would reduce body fat substantially, with preferential loss from the visceral compartment, and preserve lean tissue with a minimum of side effects. Obesity has been recognized as a chronic disease since 1985. Chronic diseases recognized before obesity may predict the future of obesity research. Initial treatments of chronic diseases commonly arise from empirical observations. These observations often stimulate basic research into the physiologic mechanisms responsible. Such cross-fertilization between the clinic and basic science is desirable and expected. As more is learned about the physiology of obesity, treatments can be expected to use more downstream mechanisms with less unwanted side effects, the reliance on surgical treatments can be expected to decline, and molecular approaches are likely to play an increasingly important role. With a better physiologic understanding of obesity, advanced clinical endpoints will become more important and molecular approaches are likely to play a more important role in discovery and treatment. Due to the availability of molecular approaches, obesity treatment is expected to advance faster than chronic disease research of the past.

Reproducibility of volumetric quantification in intravascular ultrasound images

The reproducibility of volume measurements in intravascular ultrasound (IVUS) images derived from separate pull-back manoeuvres remains to be elucidated. Patients (n = 23) were imaged with IVUS prior to (first series) and following percutaneous transluminal angioplasty (PTA) (second series). In 15 patients, one matched vascular segment (3-4 cm in length), not subjected to PTA, was used for analysis of lumen, vessel and plaque volume using an automated contour analysis system. Volume measurements assessed by two independent observers and in the two separate series were compared. Interobserver differences in volume measurements were small (< or =0.4%), with low coefficients of variation (< or =1.7%) and high correlation coefficients (r = 1.00). Differences in volume measurements obtained in the two separate series were small (< or =2.6%), with low coefficients of variation (< or = 8.6%) and high correlation coefficients (r = 0.97-0.99). In conclusion, volume measurements derived from IVUS images are highly reproducible. Therefore, IVUS may be used to monitor the progression/regression of atherosclerotic plaque volume in a longitudinal study.

Reproducibility of measurements of intima-media thickness and distensibility in the common carotid artery

OBJECTIVE

To assess reproducibility of ultrasonographic measurements of arterial distensibility and intima-media thickness (IMT) in the common carotid arteries.

DESIGN

Prospective study.

MATERIALS

Measurements of IMT and arterial distensibility were performed on-line in B-mode and M-mode, respectively. Blood pressure was assessed. From the measured variables stiffness indices were derived.

METHODS

Twenty-five persons were included in the IMT study, both healthy subjects and patients with atherosclerotic disease. Distensibility was measured in a randomly selected subgroup of 10 persons. All subjects were examined by two different sonographers on the same day and were re-examined after 1 or 2 weeks.

RESULTS

When data from both carotid arteries were combined, the interobserver coefficient of variation of IMT was on average 11.7%, of diastolic diameter 3.3% of distension and relative distension 11.8%, of distensibility coefficient 12.3%, and of stiffness parameter beta 19%. Intraobserver variability was slightly lower than interobserver variability. Variability for measurements in the right common carotid artery only was higher than for measurements of both carotid arteries combined.

CONCLUSIONS

Our study demonstrates that reproducibility of measurements of IMT and arterial distensibility of the common carotid artery, by B-mode and M-mode ultrasonography respectively, is acceptable when used in large studies.