Beneficial effects of cholesterol-lowering therapy on the coronary endothelium in patients with coronary artery disease

Endothelial function and postprandial lipemia

It is widely recognised that post-prandial lipoproteins play a role in the development of atherosclerosis, but the mechanisms underlying this role are unclear. An attractive working hypothesis is that the pathogenetic link is endothelial dysfunction. The available data seem to corroborate this theory and recognise triggering by oxidative stress, but some of the evidence is still contradictory.

EFFECTS OF FLUVASTATIN ON ENDOTHELIUM-DERIVED HYPERPOLARIZING FACTOR- AND NITRIC OXIDE-MEDIATED RELAXATIONS IN ARTERIES OF HYPERTENSIVE RATS

Endothelial cells release endothelium-derived hyperpolarizing factor (EDHF), as well as nitric oxide (NO). It has recently been suggested that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) improve NO-mediated endothelial function, partially independently of their cholesterol-lowering effects. It is, however, unclear whether statins improve EDHF-mediated responses. Eight-month-old stroke-prone spontaneously hypertensive rats (SHRSP) were treated with fluvastatin (10 mg/kg per day) for 1 month. Age-matched, normotensive Wistar Kyoto (WKY) rats served as controls. Both EDHF- and NO-mediated relaxations were impaired in SHRSP compared with WKY rats. Fluvastatin treatment did not affect blood pressure and serum total cholesterol. The acetylcholine (ACh)-induced, EDHF-mediated hyperpolarization in mesenteric arteries did not significantly differ between fluvastatin-treated SHRSP and untreated SHRSP and the responses in both groups were significantly smaller compared with those of WKY rats. Endothelium-derived hyperpolarizing factor-mediated relaxations, as assessed by the relaxation to ACh in mesenteric arteries contracted with noradrenaline in the presence of N(G)-nitro-l-arginine and indomethacin, were virtually absent and similar in both SHRSP groups. In contrast, NO-mediated relaxation, as assessed by the relaxation in response to ACh in rings contracted with 77 mmol/L KCl, was improved in fluvastatin-treated SHRSP compared with untreated SHRSP (maximum relaxation in control and fluvastatin groups 42.0 +/- 5.2 and 61.2 +/- 3.8%, respectively; P < 0.05). Hyperpolarization and relaxation in response to levcromakalim, an ATP-sensitive K(+) channel opener, were similar between the two SHRSP groups. These findings suggest that fluvastatin improves NO-mediated relaxation, but not EDHF-mediated hyperpolarization and relaxation, in SHRSP. Thus, the beneficial effects of the statin on endothelial function may be mainly ascribed to an improvement in the NO pathway, but not EDHF.

Vascular basis for the treatment of myocardial ischemia study: trial design and baseline characteristics

BACKGROUND

Increased low-density lipoprotein (LDL) and oxidized LDL cholesterol levels adversely affect endothelial function in patients with stable coronary artery disease (CAD). Statin drugs are efficacious in primary and secondary prevention of clinical CAD events, but they have not been extensively studied as a treatment for ischemia during routine daily activities or during exercise, indicators of high-risk in patients with stable CAD. The purpose of the Vascular Basis for the Treatment of Myocardial Ischemia study is to determine whether aggressive lowering of LDL cholesterol level with atorvastatin, with or without supplemental antioxidant vitamins C and E, can improve endothelial function and ischemia during ambulatory electrocardiogram (AECG) monitoring and exercise treadmill testing (ETT).

METHODS

Patients are eligible when they have ischemia during an ETT and AECG monitoring and when their fasting total cholesterol level is < or =250 mg/dL. Eligible patients are randomized to receive 1 of 3 treatments: intensive atorvastatin to reduce LDL cholesterol level to < or =80 mg/dL, intensive atorvastatin to reduce LDL cholesterol level to < or =80 mg/dL plus antioxidant vitamins C and E, and control of diet and low-dose lovastatin, when needed, to reduce LDL cholesterol level < or = to 130 mg/dL. Patients undergo endothelial function testing, 48-hour AECG monitoring, and ETT at randomization and at 6 and 12 months.

RESULTS

A total of 300 patients have been randomized: 101 to receive atorvastatin alone, 103 to receive atorvastatin plus antioxidant vitamins, and 96 to receive placebo. Baseline characteristics are similar across treatment groups.

CONCLUSIONS

The Vascular Basis study will provide important insight on the effects of aggressive management of dyslipidemia with statin drugs and antioxidant vitamins in patients with stable but high-risk CAD.

Long-term effect of combined vitamins E and C on coronary and peripheral endothelial function

OBJECTIVES

We tested whether long-term administration of antioxidant vitamins C and E improves coronary and brachial artery endothelial function in patients with coronary artery disease (CAD).

BACKGROUND

Endothelial function is a sensitive indicator of vascular health. Oxidant stress and oxidized low-density lipoprotein (LDL) impair endothelial function by reducing nitric oxide bioavailability in the artery wall.

METHODS

We randomly assigned 30 subjects with CAD to combined vitamin E (800 IU per day) and C (1000 mg per day) or to placebos in a double-blind trial. Coronary artery endothelial function was measured as the change in coronary artery diameter to acetylcholine infusions (n = 18 patients), and brachial artery endothelial function was assessed by flow-mediated dilation (n = 25 patients) at baseline and six months. Plasma markers of oxidant stress (oxidized LDL and autoantibodies) were also measured.

RESULTS

Plasma alpha-tocopherol (p < 0.001) and ascorbic acid (p < 0.02) increased with active therapy. Compared to placebo, there was no improvement in coronary and brachial endothelial vasomotor function over six months. Although vitamins C and E tended to reduce F2-isoprostanes (p = 0.065), they failed to alter oxidized LDL or autoantibodies to oxidized LDL.

CONCLUSIONS

Long-term oral vitamins C and E do not improve key mechanisms in the biology of atherosclerosis or endothelial dysfunction, or reduce LDL oxidation in vivo.

Erectile dysfunction in the cardiac patient

Erectile dysfunction (ED) is a common problem in men over 40-50 years of age. Risk factors include: diabetes, lipid abnormalities, smoking, hypertension, obesity, and lack of physical activity. Oral phosphodiesterase-5 inhibitors appear effective and safe in most cardiac patients.

Preservation of NO production by statins in the treatment of heart failure

OBJECTIVE

Because statins promote endogenous nitric oxide (NO) production in vessels by increasing endothelial nitric oxide synthase (eNOS), we evaluated the clinical benefit and efficiency of simvastatin in preventing the decrease in NO control of coronary blood flow (CBF), NO regulation of myocardial oxygen consumption (MVO(2)) and decreased nitrite production in coronary microvessels, associated with pacing-induced heart failure (HF).

METHODS

Dogs (n=17) were instrumented for measurement of coronary blood flow and left ventricular end diastolic pressure (LVEDP). HF was induced by pacing. Ten dogs were given simvastatin 20 mg/kg/day orally (HF+SIMVA) from the 10th day of pacing.

RESULTS

HF+SIMVA had a lower LVEDP at 4 weeks of pacing (18+/-1 vs. 25+/-1 mm Hg, p<0.05), and the NO-dependent coronary vasodilation to veratrine was preserved compared to HF (p<0.05). In coronary microvessels, SIMVA potentiated nitrite production compared to HF (p<0.05) and enhanced the NO-dependent decrease in MVO(2) in cardiac tissue in response to 10(-4) mol/l bradykinin, which was markedly blunted in HF (p<0.05). Using Western blotting, there was a reduction in eNOS protein during HF that was preserved at 4-5 weeks of pacing during treatment with SIMVA.

CONCLUSIONS

Simvastatin maintained NO production by coronary vessels and NO bioactivity during pacing-induced dilated cardiomyopathy. Targeting the endothelium, which participates in the control of myocardial metabolism by NO, may be an important mechanism of action of statins in the treatment of heart failure.

Determinants of platelet responsiveness to nitric oxide in patients with chronic heart failure

Congestive heart failure (CHF) is associated with oxidative stress. Platelet responsiveness to nitric oxide (NO) donors, are impaired in patients with angina pectoris, possibly by increasing oxidative stress. We investigated the occurrence of platelet resistance to NO in patients, with ischaemic or non-ischaemic cardiomyopathy compared with normal subjects. Anti-aggregatory effects of sodium nitroprusside (SNP), oxidative stress and whole blood superoxide anion content were determined, with correlates of responsiveness to SNP. Inhibition of platelet aggregation by SNP was 65.4+/-3.55% in controls and 59.3+/-4.1% in CHF (P=ns) despite increased oxidative stress and post-aggregation O2- in CHF patients. However, subsets of CHF patients have NO-resistant platelets: this is associated with increasing age and/or increased oxidative stress (both p<0.05).

Chronic treatment with fluvastatin improves smooth muscle dilatory function in genetically determined hyperlipoproteinemia

We hypothesized that the HMG-CoA reductase inhibitor fluvastatin, does not only improve endothelium-dependent vasorelaxation, but that it also increases vascular smooth muscle reactivity in hyperlipoproteinemia. New Zealand White (NZW) rabbits aged 37 weeks (control), Watanabe Heritable Hyperlipidemic rabbits (WHHL) aged 37 weeks, and WHHL aged 35 weeks with fluvastatin treatment of 17 weeks (10 mg/kg/d) were examined. Aortas were isolated for isometric tension recording. Both endothelium-dependent and independent relaxation were impaired in WHHL. Fluvastatin significantly restored impaired endothelium-independent relaxation (WHHL: 57 +/- 12 versus WHHL+ fluvastatin: 150 +/- 22%; P < 0.05) and in tendency endothelium-dependent relaxation (WHHL: 26 +/- 5 versus WHHL+ fluvastatin: 83 +/- 29%; (P = 0.07)). In parallel, fluvastatin restored nitrite plasma level in hyperlipoproteinemic animals (WHHL: 480 (13-3821) versus WHHL+ fluvastatin: 808 (467-1595) nmol; P < 0.05). Thus, chronic treatment with fluvastatin not only improves endothelial but also vascular smooth muscle function in hyperlipoproteinemia, which may contribute to the beneficial clinical effects of statins.

Benefits and risks of simvastatin in patients with familial hypercholesterolaemia

Familial hypercholesterolaemia is a frequent, inherited, monogenic disorder, associated with accelerated development of atherosclerotic disease leading to coronary artery disease. Life expectancy of patients with familial hypercholesterolaemia is reduced by 15-30 years unless they are adequately treated with lipid-lowering therapy. Given the chronic nature of this disease, the selection of a therapeutic approach should be strongly based on its long-term safety and tolerability. The introduction of HMG-CoA reductase inhibitors has revolutionised the treatment of familial hypercholesterolaemia. Simvastatin 40-80 mg/day effectively reduces serum low density lipoprotein (LDL)-cholesterol levels. Furthermore, simvastatin reduces triglycerides and mildly raises high density lipoprotein-cholesterol levels. In addition to the hypolipidaemic effect, other potentially important effects, such as improvement of endothelial function and reduction of LDL oxidation and vascular inflammation, have been associated with HMG-CoA reductase inhibitor therapy. Simvastatin has also been shown to abolish the progression, and even facilitate the regression, of existing human atherosclerotic lesions. The good safety and tolerability profile of simvastatin is clearly highlighted by the low rate of therapy discontinuation observed in several population-based clinical trials. The most common adverse events leading to the discontinuation of therapy are gastrointestinal upset and headache. Asymptomatic elevations in liver transaminase levels and myopathy are uncommon. The overwhelming clinical evidence regarding the long-term use of HMG-CoA reductase inhibitor therapy in patients with familial hypercholesterolaemia together with the long-term safety data (particularly relating to simvastatin) provide support for the use of this drug as a first-line agent when pharmacological treatment is indicated. Early intervention with simvastatin treatment can be successfully implemented with favourable economic benefits.

Improvement of endothelium-dependent coronary vasodilation after a single LDL apheresis in patients with hypercholesterolemia

The purpose of this study was to determine whether a single LDL apheresis would improve impaired endothelium-dependent dilation of the coronary artery in patients with hypercholesterolemia. Hypercholesterolemia is associated with impaired endothelial function, and human studies using cholesterol-lowering drugs indicate that endothelial function in the coronary arteries improves with reduction of serum LDL cholesterol over 6 to 12 months. The internal diameter of the left coronary artery and the coronary blood flow were measured by intracoronary Doppler-wire measurement and quantitative angiography before and immediately after a single LDL apheresis in a population of 15 patients with familial hypercholesterolemia. Endothelium-dependent vasodilation was assessed by intracoronary infusion of acetylcholine (1, 10, and 50 microg/min), and endothelium-independent vasodilation was assessed by intracoronary bolus infusion of isosorbide dinitrate (2.5 mg) or papaverine (10 mg). A single 3-hour LDL apheresis reduced serum LDL cholesterol by an average of 86.6 +/- 1.7%. After the LDL apheresis, the changes in the coronary artery diameter and coronary blood flow in response to an infusion of 50 microg/min of acetylcholine increased significantly compared to the pre-apheresis values (from -19.7 +/- 4.8 to -2.9 +/- 3.0% [P < 0.01] and from 80.7 +/- 27.6 to 155.3 +/- 23.5% [P < 0.01], respectively). The LDL apheresis did not significantly change the response of either parameter to infusion with isosorbide dinitrate or papaverine. The endothelial function of the epicardial coronary artery and the coronary microvasculature improved in hypercholesterolemic patients after only a single LDL apheresis, a procedure that markedly reduces the serum level of LDL cholesterol.

Association of dyslipidemia and effects of statins on nonmacrovascular diseases

BACKGROUND

Statins have mechanisms of action that expand their effects beyond cholesterol lowering and atherosclerotic medical conditions.

OBJECTIVE

This review summarizes clinical evidence for the association of dyslipidemia and the effects of statin use on aortic stenosis, Alzheimer's dementia (AD), osteoporosis, prevention of diabetes mellitus (DM), diabetic retinopathy, age-related macular degeneration, and diabetic/nondiabetic nephropathy.

METHODS

An English-language literature search was conducted using MEDLINE (1966-June 2003). Bibliographies of retrieved articles were reviewed. Search terms included statin, HMG-CoA reductase inhibitors, aortic stenosis, Alzheimer's dementia, osteoporosis, prevention of diabetis, diabetic retinopathy, age-related macular degeneration, diabetic nephropathy, and nondiabetic nephropathy.

RESULTS

Three retrospective cohort trials have shown an association between statin use and the progression of aortic stenosis; one of these trials observed a 45% decrease in aortic valve area in 1 year. In AD, one cross-sectional analysis found 60% to 73% lower AD rates in lovastatin or pravastatin recipients ( P<0.001 ). Of the multiple observational studies on the effect of statins on fracture risk, some have shown a decreased risk, with an odds ratio as low as 0.50 (95% CI, 0.33-0.76); others have demonstrated no association. A post hoc analysis of the West of Scotland Coronary Prevention Study found a 30% reduction in the development of DM ( P=0.042 ), but this was not duplicated in the Anglo-Scandinavian Cardiac Outcomes Trial-Lipid Lowering Arm. A small clinical trial of 6 patients (11 eyes) demonstrated improved retinal hard exudates with pravastatin treatment in patients with diabetic retinopathy. In a cross-sectional analysis, age-related macular degeneration was found to be less common among statin users than nonusers (4% [ 1/27 ] vs 22% [ 76/352 ]; P=0.02. Multiple small clinical trials of 19 to 56 patients with diabetic and nondiabetic nephropathy at various stages generated inconsistent results for an association between statin use and decreased albumin excretion rate and decreased rate of decline in glomerular filtration.

CONCLUSION

Data of variable quantity and quality support the use of statins as adjuncts in the treatment of nonmacrovascular diseases.

Long-Term Treatment with Probucol Improves Endothelial Function in Patients with Coronary Artery Disease

Recent studies have shown that endothelial function is impaired in patients with coronary artery disease (CAD). Probucol has been recognized to have antioxidant properties as well as lipid-lowering effects, and may improve endothelial function. The aim of this study was to evaluate the effects of probucol on endothelial function in patients with CAD. We evaluated endothelial function, based on flow-mediated vasodilation during reactive hyperemia (FMD), and the intima-media thickness (IMT) of the common carotid artery using high resolution ultrasonography in patients either with (CAD group, n=26) or without CAD (Control group, n=12). We measured the serum cholesterol concentration, including the low-density lipoprotein cholesterol (LDL-cholesterol) concentration, and the plasma concentrations of homocyst(e)ine and asymmetric dimethylarginine (ADMA). Measurements of FMD and serum cholesterol were repeated after 3 months of probucol (500 mg/day, n=9) or placebo (n=9) treatment in patients with CAD. The IMT was significantly greater (p < 0.001) and FMD was significantly lower (p < 0.001) in the CAD group than in the Control group. While the serum cholesterol concentration and plasma ADMA were similar in the two groups, the plasma homocyst(e)ine concentrations were higher in the CAD group than in the Control group (p < 0.01). After probucol therapy, FMD was significantly improved in the CAD group (p < 0.05). The serum LDL-cholesterol concentration did not significantly decrease after probucol treatment. Placebo treatment did not alter FMD or the serum cholesterol concentration. Our findings suggest that long-term treatment with probucol improves endothelial function in patients with CAD, an outcome independent of the LDL-cholesterol-lowering effects of probucol, and that homocyst(e)ine may be a better predictor of atherosclerosis than ADMA.

Effect of atorvastatin 80 mg on endothelial cell function (forearm blood flow) in patients with pretreatment serum low-density lipoprotein cholesterol levels <130 mg/dl

The effect of 6-week treatment with 80 mg/day atorvastatin on vascular function in the forearm was investigated in 18 patients with mean pretreatment serum low-density lipoprotein cholesterol concentrations of 112 +/- 4 mg/dl in a double-blind, placebo-controlled, randomized study. Statin treatment improved hyperemic forearm blood flow and decreased serum markers of oxidative stress and inflammation.

Effect of atorvastatin on exercise-induced myocardial ischemia in patients with stable angina pectoris

To investigate whether marked and sustained lipid-lowering in subjects with stable angina pectoris and dyslipidemia reduces exercise-induced myocardial ischemia, 17 subjects were treated with dose-adjusted atorvastatin over 1 year and underwent serial evaluation of exercise electrocardiographic ischemic parameters, serum biomarkers, and brachial artery endothelial function. Endothelial function improved progressively and C-reactive protein, P-selectin, and tissue plasminogen activator inhibitor levels decreased, but there was no decrease in exercise electrocardiographic ischemia.

Erectile dysfunction in the cardiac patient

Erectile dysfunction (ED) often is caused by endothelial dysfunction and may be a sign that a patient has vascular disease elsewhere in the body. Risk factors for coronary artery disease such as lipid abnormalities, smoking, diabetes, and hypertension also are risk factors for ED. Oral therapy for ED, such as sildenafil, inhibits phosphodiesterase-5 (PDE-5) and the breakdown of cyclic guanosine monophosphate. PDE-5 inhibitors have been shown to be safe and effective for the therapy for ED, but remain contraindicated in patients receiving organic nitrates. These agents are mild vasodilators and are being investigated for their treatment potential for patients with pulmonary hypertension, heart failure, and endothelial dysfunction.

The clinical implications of endothelial dysfunction

Defining new approaches for the prevention and treatment of atherosclerosis is an important priority. Recently, measurement of endothelial function in patients has emerged as a useful tool for atherosclerosis research. Risk factors are associated with impaired endothelial function, and clinical syndromes relate, in part, to a loss of endothelial control of vascular homeostasis. Recent studies have shown that the severity of endothelial dysfunction relates to cardiovascular risk. A growing number of interventions known to reduce cardiovascular risk have been shown to improve endothelial function. This work suggests that studies of endothelial function could be used in the care of patients and as a surrogate marker for the evaluation of new therapeutic strategies. This article will review this growing literature in an effort to evaluate the current clinical utility of endothelial dysfunction.

Rapid effect of 3-hydroxy-3-methylglutaryl coenzyme a reductase inhibition on coronary endothelial function

Treatment with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) decreases cardiovascular event rates in hypercholesterolemic patients. Whether statins exert effects within 24 hours on the coronary vasculature in patients with endothelial dysfunction has not been elucidated. Twenty-seven patients with stable angina pectoris and average low-density lipoprotein cholesterol concentrations of 138+/-9 mg/dL at baseline were allocated to treatment with placebo (14 patients) or 40 mg/d pravastatin (13 patients) in a randomized, double-blind, prospective trial. Coronary endothelial function was assessed before and 24 hours after single treatment by quantitative coronary angiography during intracoronary infusion of nitroglycerin or increasing concentrations of acetylcholine (0.01, 0.1, and 1 micromol/L). Coronary blood flow reserve was measured by Doppler velocimetry during adenosine infusion. Intracoronary acetylcholine infusion induced abnormal vasoconstriction in both groups before treatment, indicating coronary endothelial dysfunction. Treatment with a single oral 40-mg dose of pravastatin significantly attenuated acetylcholine-mediated vasoconstriction after 24 hours (mean+/-SE decrease in luminal diameter before and after treatment: 0.01 micromol/L, 6.1+/-2.2% versus 3.0+/-1.2%; 0.1 micromol/L, 15.6+/-2.6% versus 7.4+/-1.8%; P<0.05; 1 micromol/L, 22.9+/-2.9% versus 13.2+/-2.6%; P<0.05). There was no significant difference in the response to acetylcholine in the placebo group (8.1+/-2.4% versus 9.7+/-2.4%, 16.1+/-2.9% versus 16.8+/-3.2%, and 21.4+/-3.9% versus 23.3+/-4.2%). The response to nitroglycerin infusion was not altered in both groups. Increase in coronary blood flow in response to adenosine and coronary flow reserve remained unchanged during placebo and statin treatment. Serum concentrations of blood lipids and high-sensitive C-reactive protein were not significantly altered after 24 hours in response to placebo or pravastatin therapy. Statin treatment improves endothelium-dependent coronary vasomotion within 24 hours in the absence of significant cholesterol reduction. The full text of this article is available online at http://www.circresaha.org.

Rapid effects of simvastatin on lipid profile and C-reactive protein in patients with hypercholesterolemia

BACKGROUND

Rapid lowering of low-density lipoprotein (LDL) cholesterol levels as well as C-reactive protein (CRP) by administration of drugs may produce early benefit to the coronary endothelium in patients with coronary heart disease and reduce angina and coronary events after revascularization. Limited information has been available in evaluating a potentially effective first 2-week therapeutic approach for the treatment of patients with hypercholesterolemia using a statin.

HYPOTHESIS

The study was undertaken to investigate whether a rapid LDL cholesterol and CRP reduction can be achieved by 2-week simvastatin therapy using a common lipid-lowering protocol in patients with hypercholesterolemia.

METHODS

Forty-two patients were randomly assigned to 20 or 40 mg/day of simvastatin. Blood samples were drawn at Day 0 and at Day 14 for measuring lipid profile, CRP levels, and hepatic enzymes in all patients.

RESULTS

The results showed that both doses of simvastatin (20 and 40 mg) induced significant reductions in total cholesterol (TC, 25 and 38%) and LDL cholesterol (31 and 46%) compared with baseline. However, the highest dose of simvastatin (40 mg) resulted in significantly greater reductions in TC and LDL cholesterol (p = 0.04, p = 0.02, respectively) compared with the group receiving 20 mg (p < 0.04, p < 0.02, respectively). A less significant reduction was observed in mean triglycerides (TG) level (16 and 25%) compared with TC and LDL cholesterol. There was no significant difference in mean high-density lipoprotein (HDL) cholesterol levels compared with baseline in either group. In addition, both doses of simvastatin induced significant reductions in mean CRP levels on Day 14 (22.3 and 23.1%) in a non dose-dependent manner (p < 0.001, respectively.

CONCLUSIONS

Our data suggest that a common daily dose of simvastatin, especially 40 mg, is an effective 2-week therapy for patients with hypercholesterolemia, and benefit to the vascular endothelium can be derived quickly by reduction of CRP levels.

Efficacy of fenofibrate and simvastatin on endothelial function and inflammatory markers in patients with combined hyperlipidemia: relations with baseline lipid profiles

Given that combination therapy with statin plus fibrate confers a risk of myopathy, it is worthwhile to determine whether statin or fibrate monotherapy is associated with greater clinical benefit in individuals with combined hyperlipidemia. In this randomized double-blind study, we compared the efficacy of simvastatin and fenofibrate on indexes of endothelial function (flow-mediated dilation (FMD) of the brachial artery) and inflammatory markers (plasma high-sensitivity C-reactive protein (CRP), interleukin-1 beta (IL-1 beta), soluble CD40, and soluble CD40 ligand (sCD40L) levels), as surrogate indicators of future coronary heart disease (CHD), in patients with combined hyperlipidemia. A total of 70 patients with plasma triglyceride levels between 200 and 500 mg/dl and total cholesterol levels of >200 mg/dl were randomly assigned to receive either simvastatin (20 mg/day) (n=35) or micronized fenofibrate (200 mg/day) (n=35) for 8 weeks. Treatment with simvastatin was associated with significantly greater reduction of total cholesterol and low-density lipoprotein cholesterol (LDL-C), while the decrease in triglycerides was significantly greater in patients receiving fenofibrate. Both fenofibrate and simvastatin markedly reduced plasma levels of high-sensitivity CRP, IL-1 beta, and sCD40L, and improved endothelium-dependent FMD without mutual differences. The changes in plasma inflammatory markers did not correlate with baseline clinical characteristics in both groups. However, the improvement in FMD with fenofibrate treatment correlated inversely with baseline high-density lipoprotein cholesterol (HDL-C) levels, whereas the improvement in FMD with simvastatin treatment was positively related to HDL-C levels. Accordingly, in the subgroup with a baseline HDL-C of < or =40 mg/dl, only fenofibrate significantly improved the endothelium-dependent FMD. On the other hand, in the subgroup with HDL-C >40 mg/dl, only treatment with simvastatin achieved significant improvement in FMD. The data here indicate that in patients with combined hyperlipidemia, both fenofibrate and simvastatin have comparative beneficial effects on various inflammatory markers and differential beneficial effects on endothelial function according to baseline HDL-C levels. These findings should be validated by additional prospective studies, in which patients are stratified by baseline HDL-C prior to randomization.

Interleukin-1B genotype modulates the improvement of coronary artery reactivity by lipid-lowering therapy with pravastatin

A polymorphism at position -511 of interleukin-1B (IL-1B) gene promoter regulates IL-1B levels, immune and inflammatory responses and possible atherogenesis. We used positron emission tomography (PET) to study whether coronary reactivity or its response to pravastatin is related to this IL-1B polymorphism. The study comprised a randomized, double-blind, placebo-controlled trial with two treatment groups: (i) pravastatin (40 mg/day, n=14) and (ii) placebo (n=20) for 6 months (baseline mean cholesterol 5.5 +/- 0.8 mmol/l; age 35 +/- 4 years). Myocardial blood flow was measured by PET at rest and during adenosine infusion using 15O-labelled water. PET studies, lipid, IL-1beta and C-reactive protein analyses were performed at baseline and after 6 months of therapy. IL-1B genotype was determined by polymerase chain reaction. There were no differences between IL-1B allele 2 carriers (A2+) and non-carriers (A2-) in basal or adenosine-stimulated myocardial flow (ASMF), at baseline. Regarding the change in ASMF and coronary flow reserve, there was a significant IL-1B genotype-by-treatment group interaction (analysis of covariance, P=0.028 and P=0.002, respectively) during follow-up. In the pravastatin group, the ASMF increased by 18.0% in subjects with IL-1B A2- (n=7), but decreased by 2% in subjects with IL-1B A2+ (n=7). There were no significant changes from the baseline values in placebo recipients. After treatment, both genotype groups showed a similar decrease in serum total and low density lipoprotein cholesterol (P<0.0001 for both). In conclusion, coronary function improves after 6 months of pravastatin therapy in subjects with the IL-1B A2- allele but not in those with the IL-1B A2+ allele.

Effects of atorvastatin on in-stent stenosis in normo- and hypercholesterolemic rabbits

BACKGROUND

In-stent stenosis is characterized by a prolonged proliferation and inflammatory reactions around the stent struts. Potentially the antiproliferative and lipid-lowering effects of atorvastatin can synergistically limit neointima formation after stenting.

METHODS

Palmaz-Schatz stents were placed in the iliac arteries of white New Zealand rabbits. One half of the animals was fed an 0.5% hypercholesterolemic diet, the other half was normocholesterolemic. Both groups received either atorvastatin (3 mg/kg bodyweight) daily or placebo (n=10 each in the four groups). After 28 days the segments were excised.

RESULTS

Injury scores as a result of vessel trauma induced by stent-overstretch injury differed significantly between the four groups (median 1.0-1.9) and the stent-induced injury outweighed the beneficial effects of statin therapy on neointima formation by far. Smooth-muscle-cell proliferation was significantly increased in both hypercholesterolemic groups. Intimal and medial proliferation as well as inflammatory infiltrates around the stent strut were reduced by 20-40% in animals that received statin therapy although the injury score in both statin groups was 19 and 60% higher than in control animals.

CONCLUSION

Thus, the data of this study indicate that smooth muscle cell proliferation and inflammation in stented vessels can be reduced by atorvastatin both in hypercholesterolemic rabbits and in animals with normal lipid levels.

Prospective serial evaluation of myocardial perfusion and lipids during the first six months of pravastatin therapy: coronary artery disease regression single photon emission computed tomography monitoring trial

OBJECTIVES

This study was designed to assess prospectively changes in serum lipid profile and myocardial perfusion with serial radionuclide single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) during the first six months of pravastatin therapy.

BACKGROUND

Morbid coronary events occur despite statin therapy and lipid-lowering in patients with coronary artery disease (CAD). A reliable strategy to identify responders with effective treatment from nonresponders on statin therapy before clinical events is needed.

METHODS

Rest and stress SPECT MPI and lipids were assessed serially in 25 patients (36% women) with CAD and dyslipidemia during the first six months of pravastatin therapy.

RESULTS

Total cholesterol, low-density lipoprotein cholesterol, and triglycerides declined (26%, 32%, and 30%, respectively) by six weeks and remained reduced at six months. Mean stress perfusion defect (summed stress score [SSS]) was severe (13.3 +/- 6.0) at baseline, showed no change at six weeks, and improved significantly at six months (10.3 +/- 7.3, p < 0.01). The six-month study SSS improved in 11 (48%) patients, was unchanged in 10 (43%) patients, and worsened in 2 (9%) patients. Changes in lipid levels did not reliably predict changes in myocardial perfusion at six weeks or six months in this small pilot study.

CONCLUSIONS

Serial SPECT MPI demonstrated improved stress myocardial perfusion in 48% of patients treated for six months with pravastatin. Time course of improved myocardial perfusion during pravastatin therapy is delayed compared to lipids. Direction and magnitude of changes in the myocardial perfusion vary and do not correlate closely with improvements in lipids.

Effects of raloxifene on endothelium-dependent dilation, lipoproteins, and markers of vascular function in postmenopausal women with coronary artery disease

OBJECTIVES

We sought to assess the effects of raloxifene, a selective estrogen receptor modulator, on arterial physiology and biology in postmenopausal women with coronary artery disease (CAD).

BACKGROUND

Raloxifene improves endothelial function and markers of vascular health in vitro in experimental animals and in healthy postmenopausal women. In women whose arteries are affected by advanced atherosclerosis, however, the vascular effects of estrogen receptor modulation are unknown.

METHODS

We conducted a prospective, randomized, double-blinded, placebo-controlled, crossover trial of raloxifene, 60 mg/day for 8 weeks, in 33 consecutively eligible and consenting postmenopausal women age 50 to 75 years with known CAD. Parameters measured at the beginning and end of each treatment period included brachial artery flow-mediated dilation (FMD), the primary end point, as well as nitroglycerin-induced dilation, peripheral artery tonometry, serum lipoprotein levels, and markers of vascular function, including urinary prostaglandin, serum endothelin-1, and fibrinogen levels.

RESULTS

Baseline FMD was impaired in these women, as expected (2.84 +/- 0.60%), but there was no significant difference between the effect of raloxifene (0.26 +/- 0.66% increase) and placebo (0.01 +/- 0.63% decrease) on this marker of endothelial function (p = 0.82). No significant raloxifene-related effects were observed on derived aortic pressure, pulse pressure, augmentation index, total cholesterol or low- and high-density lipoprotein subfractions, markers of thrombosis, or vasoconstrictor or vasodilator substances.

CONCLUSIONS

In postmenopausal women with treated CAD, selective estrogen receptor modulation with raloxifene does not improve a comprehensive set of parameters examining vascular function and serum lipoprotein levels.

Short-term statin therapy improves cardiac function and symptoms in patients with idiopathic dilated cardiomyopathy

BACKGROUND

Chronic heart failure is associated with inflammation and neurohormonal imbalance. The 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors, or statins, exert anti-inflammatory and vascular protective effects. We hypothesized that short-term statin therapy may have beneficial effects in patients with nonischemic heart failure.

METHODS AND RESULTS

Sixty-three patients with symptomatic, nonischemic, dilated cardiomyopathy were randomly divided into 2 groups. One group received simvastatin (n=24), and the other group received placebo (n=27). The initial dose of simvastatin was 5 mg/d, which was increased to 10 mg/d after 4 weeks. After 14 weeks, patients receiving simvastatin exhibited a modest reduction in serum cholesterol level compared with patients receiving placebo (130+/-13 versus 148+/-18, P<0.05). Patients treated with simvastatin had a lower New York Heart Association functional class compared with patients receiving placebo (2.04+/-0.06 versus 2.32+/-0.05, P<0.01). This corresponded to improved left ventricular ejection fraction in the simvastatin group (34+/-3 to 41+/-4%, P<0.05) but not in the placebo group. Furthermore, plasma concentrations of tumor necrosis factor-alpha, interleukin-6, and brain natriuretic peptide were significantly lower in the simvastatin group compared with the placebo group.

CONCLUSIONS

Short-term statin therapy improves cardiac function, neurohormonal imbalance, and symptoms associated with idiopathic dilated cardiomyopathy. These findings suggest that statins may have therapeutic benefits in patients with heart failure irrespective of serum cholesterol levels or atherosclerotic heart disease.

Atheroprotective effects of long-acting dihydropyridine-type calcium channel blockers: evidence from clinical trials and basic scientific research

Atherosclerosis is a systemic disease that can ultimately lead to ischaemia and infarction in the heart, brain and peripheral vasculature. According to the "response to injury" hypothesis, endothelial dysfunction is the early event that allows penetration of lipids and inflammatory cells into the arterial wall, contributing to the development of the atherosclerotic lesion. Endothelial dysfunction is causally related to a variety of risk factors for atherosclerosis, including hyperlipidaemia and hypertension. Agents that restore endothelial function and NO bioavailability have beneficial anti-atherogenic activities and can improve cardiovascular outcomes; this has been observed with angiotensin-converting enzyme (ACE) inhibitors, statins and certain dihydropyridine-type calcium channel blockers (CCBs). In the Prospective Randomised Evaluation of the Vascular Effects of Norvasc Trial (PREVENT), the CCB amlodipine provided significant clinical benefits compared with placebo, including a marked reduction in cardiovascular morbidity and a reduction in the progression of carotid atherosclerosis. As these beneficial effects of amlodipine have not been observed with other dihydropyridine-type CCBs, it has been proposed that this agent has distinct anti-atherosclerotic properties related to its strong lipophilicity and membrane location. Experimental support for this hypothesis has been obtained from various in vitro and in vivo models of atherosclerosis. These findings support a broader therapeutic role for third-generation dihydropyridine-type CCBs in the treatment of atherosclerosis.

Endothelial dysfunction: clinical strategies for treating oxidant stress

BACKGROUND

A growing body of evidence has demonstrated that oxidants play a critical role in the pathogenesis of endothelial dysfunction. Pathologic processes fundamental to development and progression of endothelial dysfunction such as the oxidation of LDL, the loss of bioavailable nitric oxide, and the vascular inflammatory response are all modulated by oxidant stress. Therapeutic strategies to reverse endothelial dysfunction have begun to focus on agents with the ability to ameliorate oxidant stress.

METHODS

Preclinical and clinical studies evaluating the actions of antioxidants as well as traditional cardiovascular therapies in ameliorating oxidative stress and endothelial dysfunction were reviewed through the use of a MEDLINE search of English language articles published between the years of 1992 and 2002.

RESULTS

Antioxidants appear to be an attractive candidate therapy, yet despite compelling preclinical evidence supporting their benefits, efforts to validate the use of vitamins C and E in a clinical setting have been conflicting. In contrast, conventional cardiovascular therapies such as ACE inhibitors, statins, insulin-sensitizing agents, and estrogens have been shown to alleviate endothelial dysfunction, often independent of their effects on systemic disease processes.

CONCLUSIONS

These agents restore endothelial function through their salutary effects on pathologic vascular oxidative processes.

Low-density lipoprotein apheresis in the prevention of recurrent coronary heart disease: a review

This article summarizes the clinical evidence for low-density lipoprotein (LDL) apheresis to improve prognosis of patients with coronary heart disease. Regarding clinical events or angiographic parameters, most trials have revealed favorable effects on coronary artery disease. In the studies with a clinical endpoint, approximately 50% reduction in incidence of major coronary events was achieved by LDL apheresis. Similarly, in the studies with a angiographic parameter, coronary atherosclerosis was suppressed or regressed by LDL apheresis. The mechanisms of these effects by LDL apheresis are attributed to improvement in coronary flow reserve, which is dependent upon increases in hemo-rheological factor, nitric oxide, vasoactive substances or decrease of oxidized LDL. These new insights into mechanisms will expand the indication of LDL apheresis to other pathophysiological conditions of coronary artery disease and other disorders.

Low-density lipoprotein apheresis: an overview

Atherosclerosis with myocardial infarction, stroke, and peripheral cellular disease still maintains its position at the top of morbidity and mortality statistics in industrialized nations. Established risk factors widely accepted are smoking, arterial hypertension, diabetes mellitus, and central obesity. Furthermore, there is a strong correlation between hyperlipidemia and atherosclerosis. The prognosis of patients suffering from severe hyperlipidemia, sometimes combined with elevated lipoprotein (a) (Lpa) levels, and coronary heart disease (CHD) refractory to diet and lipid-lowering drugs is poor. For such patients, regular treatment with low-density lipoprotein (LDL) apheresis is the therapeutic option. Today, there are four different LDL apheresis systems available: immunoadsorption, heparin-induced extracorporeal LDL/fibrinogen precipitation, dextran sulfate LDL adsorption and LDL hemoperfusion. Regarding the different LDL apheresis systems used, there is no significant difference with respect to the clinical outcome or concerning total cholesterol, LDL, high-density lipoprotein (HDL), or triglyceride concentrations. With respect to elevated Lpa levels, however, the immunoadsorption method seems to be the most effective. In 45 patients (25 women, 20 men) suffering from familial hypercholesterolemia resistant to diet and lipid lowering drugs, low-density lipoprotein (LDL) apheresis was performed over 95.6 +/- 44.7 months. Four different systems (Liposorber, 32 of 45, Kaneka, Osaka, Japan; Therasorb, 6 of 45, Baxter, Munich, Germany; Lipopak, 2 of 45, Pocard, Moscow, Russia; and Dali, 5 of 45, Fresenius, St. Wendel, Germany) were used. With all methods, average reductions of 57% for total cholesterol, 55.9% for LDL, 75.8% for lipoprotein a (Lpa), and 45.9% for triglycerides, and an average increase of 14.3% for HDL were reached. Severe side-effects such as shock or allergic reactions were very rare (0.3%) in all methods. In the course of treatment, an improvement in general well-being and increased performance were experienced by 44 of 45 patients. The present data demonstrate that treatment with LDL apheresis of patients suffering from familial hypercholesterolemia resistant to maximum conservative therapy is very effective and safe even in long-term application.

Effects of simvastatin on endothelial function after chronic inhibition of nitric oxide synthase by L-NAME

Blood pressure, plasma NO(2) and NO(3) level, heart weight index, antioxidant enzyme activity, and vascular reactivity in rat intact aortic rings were assessed to investigate the effects of 8-week treatment with the hydroxy-methyl-glutaryl coenzyme A reductase inhibitor simvastatin (1 mg/kg per day) on endothelial dysfunction induced by chronic Nomega-nitro-l-arginine methyl ester (l-NAME 70 mg/kg per day). Results were compared with those obtained in rats receiving l-NAME, simvastatin or control animals. Coadministration of simvastatin did not restore l-NAME-increased blood pressure but normalized heart weight index (P < 0.05), endothelium-dependent relaxation to acetylcholine (P < 0.001), and plasma NO(2) and NO(3) concentration (P < 0.001) without affecting relaxation to sodium nitroprusside. Endothelium-dependent relaxation in these animals was abolished by acute incubation with l-NAME, unaffected by thromboxane synthetase inhibitor and TXA(2)/PGH(2) receptor antagonist, ridogrel, and decreased by indomethacin. Simvastatin treatment also increased plasma NO(2)+NO(3) without affecting endothelial function, heart weight index, and blood pressure of control rats. The presence of superoxide dismutase (SOD) and catalase improved endothelial relaxation only in l-NAME-treated rats, but O(2)- generated by hypoxanthine and xanthine oxidase inhibited the relaxant effect in both l-NAME and simvastatin plus l-NAME-treated rats. SOD activity was increased in all groups receiving simvastatin. Long-term treatment with simvastatin restored l-NAME-induced endothelial dysfunction, probably by preventing nitric oxide decrease. Other effects of simvastatin, including release of compensating vasodilatory cyclo-oxygenase products and increased SOD activity, could also be involved.

Soluble intercellular adhesion molecule-1 and interleukin-6 levels reflect endothelial dysfunction in patients with primary hypercholesterolaemia treated with atorvastatin

Adhesion molecules and cytokines are involved in the pathogenesis of intimal injury in atherosclerosis but their relationship with endothelial function remains unclear. The objectives of this study were to examine the effects of atorvastatin on soluble adhesion molecules, interleukin-6 (IL-6) and brachial artery endothelial-dependent flow mediated dilatation (FMD) in patients with familial (FH) and non-familial hypercholesterolaemia (NFH). A total of 74 patients (27 FH and 47 NFH) were recruited. Fasting lipid profiles, soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular-cellular adhesion molecule-1 (sVCAM-1), E-selectin, IL-6 and FMD were measured at baseline, 2 weeks, 3 and 9 months post-atorvastatin treatment (FH--80 mg/day, NFH--10 mg/day). In both groups, compared to baseline, sICAM-1 levels were significantly reduced at 2 weeks, further reduced at 3 months and maintained at 9 months (P<0.0001). The IL-6 levels were significantly reduced at 3 months and 9 months compared to baseline for FH (P<0.005) and NFH (P<0.0001). In both groups, the FMD at 2 weeks was higher than baseline (P<0.005), with progressive improvement up to 9 months. FMD was negatively correlated with sICAM-1 and IL-6. In conclusion, both low and high doses of atorvastatin lead to early progressive improvement in endothelial function in patients with primary hypercholesterolaemia. sICAM-1 and IL-6 levels reflect endothelial dysfunction in these patients.

Statin treatment and progression of atherosclerotic plaque burden

Atherosclerosis is a progressive systemic disorder that, in the initial stages, is often asymptomatic. The measurement of atherosclerotic burden using imaging techniques enables the clinical benefits of lipid-modifying therapies to be assessed in early atherosclerosis and facilitates more rapid evaluation of interventions in clinical trials compared with the measurement of clinical outcome. The effect of HMG-CoA reductase inhibitors, commonly referred to as 'statins', on disease progression has been assessed in a number of imaging studies both in patients with established coronary heart disease (CHD) and in those with subclinical atherosclerosis. Statins slow plaque progression and, in early atherosclerosis, they have been demonstrated to promote regression of atherosclerotic lesions. The benefits of statin therapy on soft atherosclerotic plaques that are still developing support the use of vascular measures to detect subclinical atherosclerosis, and the subsequent early intervention with statin therapy. Moreover, given that the effects of statins on atherosclerosis progression are evident even in normocholesterolaemic patients at increased risk of developing CHD, early intervention with statin therapy may be effective in preventing CHD, irrespective of lipid level.

Statins enhance postischemic hyperemia in the skin circulation of hypercholesterolemic patients: a monitoring test of endothelial dysfunction for clinical practice?

OBJECTIVES

The present study aims to investigate whether laser Doppler flowmetry can be used to monitor improvements in vascular function during statin therapy.

BACKGROUND

Endothelial dysfunction is an early feature of atherosclerosis in hypercholesterolemic patients and can be improved by statins. There are several methods to assess endothelial function in vivo, none of them being feasible in everyday practice.

METHODS

Skin perfusion, measured by laser Doppler flowmetry, was assessed at rest and during reactive hyperemia. Nineteen hypercholesterolemic patients (age 42 to 73 years, total cholesterol 5.4 to 9.6 mmol/l) were studied before and during statin therapy. To further investigate the mechanisms, postischemic skin hyperemia was measured before and after intradermal injection of the nitric oxide synthase inhibitor L-NAME and its inactive isoform D-NAME (0.5 micromol/10 microl each). On a separate day, the healthy volunteers were reexamined before and 2 h after 1,000 mg aspirin.

RESULTS

Postischemic skin blood flow was markedly reduced in hypercholesterolemic patients (45 +/- 11%) compared with healthy controls (238 +/- 20%, p < 0.0001) and improved after statin therapy (113 +/- 15%, p = 0.0005 vs. pre-treatment). In the healthy volunteers, the hyperemic responses were not significantly different after L-NAME and D-NAME. Aspirin reduced hyperemia from 274 +/- 49% to 197 +/- 40% (p = 0.025).

CONCLUSIONS

Reactive hyperemia of the skin microcirculation can be easily and reproducibly assessed by laser Doppler flowmetry. Vasodilator prostaglandins are the major mediators of postischemic skin hyperemia, which is impaired in hypercholesterolemic patients and can be enhanced by cholesterol-lowering therapy. Thus, laser Doppler flowmetry may represent a tool to assess and monitor vascular function during therapy in everyday practice.

Effect of atorvastatin on postcardiac transplant increase in low-density lipoprotein cholesterol reduces development of intimal hyperplasia and progression of endothelial dysfunction

Following cardiac transplantation, accelerated coronary disease limits long-term survival. Because statins may reduce the progression of the disease in part by their anti-inflammatory effects, this study was designed to assess if atorvastatin prevented neointimal hyperplasia and endothelial dysfunction independently of baseline cholesterol levels. Patients were randomized to usual therapy (n = 13) or to 10 to 20 mg of atorvastatin (n = 12). Control subjects received niacin when their low-density lipoprotein (LDL) cholesterol levels were >130 mg/dl (n = 4). Neointimal hyperplasia by intracoronary ultrasonography, endothelial dependent vascular reactivity, and coronary flow reserve were measured at baseline and 1 year. Control group total cholesterol (203 +/- 11 to 200 +/- 13 mg/dl) and LDL (116 +/- 10 to 119 +/- 11 mg/dl) remained stable, whereas there was a nonsignificant reduction at 12 months in the atorvastatin group (total cholesterol 216 +/- 28 to 178 +/- 21 mg/dl; LDL 126 +/- 17 to 100 +/- 18 mg/dl). At 2 to 3 months there was a significant increase in total cholesterol and LDL cholesterol that was reduced with atorvastatin. At 1 year, patients taking atorvastatin showed a decrease in new or progressing lesions (2.5 +/- 1.7 vs 4.2 +/- 1.8 lesions/patient, p = 0.02), progression of maximal intimal thickness (0.12 +/- 0.07 vs 0.52 +/- 0.17 mm, p = 0.04), and percent area stenosis (5.9 +/- 2.2% vs 19.0 +/- 5.5%, p = 0.04). Atorvastatin ameliorated progressive endothelial dysfunction, whereas coronary flow reserve was unchanged in both groups. Atorvastatin administered to patients with normal or mild hypercholesterolemia in the initial year after transplant reduced the initial increase in LDL cholesterol, and, by doing so, prevented the development and progression of coronary artery lesions and endothelial dysfunction with only mild long-term decreases in cholesterol levels.

The lipid and non-lipid effects of statins

The 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-CoA) reductase inhibitors, more commonly known as statins, are a class of drug widely used for the treatment of hypercholesterolaemia in patients with established cardiovascular disease as well as those at high risk of developing atherosclerosis. Their predominant action is to reduce circulating levels of low-density lipoprotein (LDL) cholesterol; to a smaller degree, they also increase high-density lipoprotein (HDL) cholesterol and reduce triglyceride concentrations. In recent years, however, there has been an increasing body of evidence that their effects on lipid profile cannot fully account for their cardiovascular protective actions: their beneficial effects are too rapid to be easily explained by their relatively slow effects on atherogenesis and too large to be accounted for by their relatively small effects on plaque regression. Experimental models have revealed that statins exert a variety of other cardiovascular effects, which would be predicted to be of clinical benefit: they possess anti-inflammatory properties, as evidenced by their ability to reduce the accumulation of inflammatory cells in atherosclerotic plaques; they inhibit vascular smooth muscle cell proliferation, a key event in atherogenesis; they inhibit platelet function, thereby limiting both atherosclerosis and superadded thrombosis; and they improve vascular endothelial function, largely through augmentation of nitric oxide (NO) generation. The relative importance of the lipid- and non-lipid-related effects of the statins in the clinical situation remains the subject of much continuing research.

Statin therapy for the treatment of diabetic dyslipidemia

The increasing prevalence of type 2 diabetes is a major problem for healthcare providers globally, since it is associated with serious microvascular and macrovascular complications. Although microvascular complications can be largely reduced with strict glycemic control, prevention of macrovascular disease involves a multifaceted approach that addresses all major risk factors, including dyslipidemia, hypertension, and insulin insensitivity. In particular, the treatment of diabetic dyslipidemia is a major challenge for diabetologists and cardiologists, as it is characterized by an array of lipid abnormalities. The management of diabetic dyslipidemia should initially include lifestyle approaches such as improved nutrition and weight reduction; however, the majority of patients require the addition of pharmacotherapy. Whilst insulin and/or oral hypoglycemic drugs are generally prescribed for the treatment of hyperglycemia, the addition of lipid-lowering drugs may be necessary for the control of diabetic dyslipidemia. The American Diabetes Association guidelines recommend lowering of low-density lipoprotein cholesterol (LDL-C) as a first priority. Hydroxy-methylglutaryl coenzyme A reductase inhibitors (statins) are recommended for first-line therapy in diabetic patients, since these agents are effective at reducing LDL-C levels. Whilst statins provide effective control of dyslipidemia in the majority of patients, more efficacious treatment regimens would provide greater benefit to more patients. Combination therapies may provide one solution to obtaining maximal lipid profile modifications, although the introduction of new, more efficacious agents for use as monotherapy may provide a more acceptable option, as drug combinations are often associated with poor tolerability and patient compliance.

Acute vasodilator effects of HMG-CoA reductase inhibitors: involvement of PI3-kinase/Akt pathway and Kv channels

3-hydroxy-3-methylglutaryl Coenzyme A (HMG-CoA) reductase inhibitors (statins) have several non-lipid-lowering actions; however, characteristics of their acute vasodilator effects remain to be elucidated. In this study, acute vasodilator effects of statins were examined in isolated rat blood vessels. After incubation with cerivastatin (1 microM) for 2 hours, acetylcholine-induced endothelium-dependent relaxations were enhanced in the rat aorta. This effect was abolished by a nitric oxide synthase (NOS) inhibitor, L-NNA, and by a PI3 kinase inhibitor, LY294002. Western blot analysis showed that the extent of phosphorylation of Akt, an active form of Akt, was increased by cerivastatin while it was reduced by LY294002, suggesting an involvement of PI3 kinase/Akt-dependent activation of endothelial NOS. At higher concentrations (1-300 microM), both cerivastatin and fluvastatin, but not pravastatin, directly relaxed the blood vessels, regardless of the presence or absence of the endothelium. These relaxations were abolished by KCl and were significantly inhibited by an inhibitor of Kv channel, 4-aminopyridine. These results indicate that multiple mechanisms are involved in the acute vasodilator effects of statins, including augmentation of nitric oxide-mediated endothelium-dependent relaxations through the PI3 kinase/Akt pathway and endothelium-independent relaxations via Kv channel-mediated smooth muscle hyperpolarizations. These acute vasodilator effects of statins may account, at least in part, for their beneficial effects on cardiovascular diseases associated with impaired organ blood flow.

Regular physical activity improves endothelial function in patients with coronary artery disease by increasing phosphorylation of endothelial nitric oxide synthase

BACKGROUND

In stable coronary artery disease (CAD), exercise training has well-documented positive effects on arterial endothelial function. NO derived from endothelial NO synthase (eNOS) is regarded as a protective factor against atherosclerosis. The aim of the present study was to investigate the effects of exercise training on the endothelial function in relation to the expression of eNOS and Akt-dependent eNOS phosphorylation in the left internal mammary artery (LIMA) of patients with stable CAD.

METHODS AND RESULTS

In 17 training patients (T) and 18 control patients (C), endothelium-dependent vasodilation and average peak flow velocity (APV) in response to acetylcholine were measured invasively at study beginning and after 4 weeks in the LIMA. In LIMA tissue sampled during bypass surgery, eNOS expression and content of pospho-eNOS-Ser1177, Akt, and phospho-Akt were determined by Western blot and quantitative reverse transcriptase-polymerase chain reaction. After exercise training, LIMA APV in response to acetylcholine was increased by 56+/-8% (from +48+/-8% at beginning to +104+/-11% after 4 weeks, P<0.001). Patients in T had a 2-fold higher eNOS protein expression (T 1.0+/-0.7 versus C 0.5+/-0.3 arbitrary units, P<0.05) and 4-fold higher eNOS Ser1177-phosphorylation levels in LIMA-endothelium (1.2+/-0.9 versus 0.3+/-0.2 arbitrary units, P<0.01). A linear correlation was confirmed between Akt phosphorylation and phospho-eNOS levels (R=0.80, P<0.05) and between phospho-eNOS and Delta APV (R=0.59, P<0.05).

CONCLUSIONS

Exercise training in stable CAD leads to an improved agonist-mediated endothelium-dependent vasodilatory capacity. The change in acetylcholine-induced vasodilatation was closely related to a shear stress-induced/Akt-dependent phosphorylation of eNOS on Ser1177.

Association between increased serum cholesterol and signs of depressive mood

Hypercholesterolemia is associated with an increased risk of atherosclerosis and coronary heart disease. Therefore, therapeutic lowering of cholesterol is an important preventive measure of cardiac morbidity and death. As one side effect, cholesterol-lowering drugs appear to increase the mortality due to suicides or violence, and low lipid concentrations were found to be associated with trait measures of depression. We compared serum cholesterol concentrations and the Beck Depression Rating Scale (Beck's score) in 604 otherwise healthy outpatients who visited the physician's office for a medical health check-up; 65.4% of individuals presented with serum cholesterol concentrations > or = 5.2 mmol/l (> 200 mg/dl) and 5.3% had elevated Beck's score (> 19), indicative for depression. Beck's score was higher in patients with cholesterol concentrations above the 75th percentile (= 6.2 mmol/l; U = 31221, p < 0.02, Mann-Whitney U-test), and Beck's score correlated with cholesterol concentrations and with age. Thus, in contrast to the widely accepted view, in our study, higher cholesterol concentrations were associated with signs of depressive mood. Hypercholesterolemia may not necessarily increase the risk of depressive mood, conversely, increased intake of fat and carbohydrates by individuals with depressive mood may increase cholesterol levels.

Nitric oxide synthase 3-dependent vascular remodeling and circulatory dysfunction in cirrhosis

Vascular remodeling is an active process that consists in important modifications in the vessel wall. Endothelium-derived nitric oxide (NO) plays a major role in this phenomenon. We assessed wall thickness (WT), total wall area (TWA), lumen diameter, and total nuclei number/cross-section (TN) in cirrhotic rats with ascites and in control rats. A second group of cirrhotic rats received the NO synthesis inhibitor, L-NAME, or vehicle daily for 11 weeks and systemic hemodynamics, arterial compliance, aortic NO synthase 3 (NOS3) protein expression, and vascular morphology were analyzed. Cirrhotic vessels showed a significant reduction in WT, TWA, and TN as compared to control vessels. Long-term inhibition of NOS activity in cirrhotic rats resulted in a significant increase in WT, TWA, and TN as compared to cirrhotic rats receiving vehicle. NOS3 protein abundance was higher in aortic vessels of nontreated cirrhotic animals than in controls. This difference was abolished by chronic treatment with L-NAME. NOS inhibition in cirrhotic rats resulted in higher arterial pressure and peripheral resistance and lower arterial compliance than cirrhotic rats receiving vehicle. Therefore, vascular remodeling in cirrhosis with ascites is a generalized process with significant functional consequences that can be negatively modulated by long-term inhibition of NOS activity.

Endothelium-dependent effects of statins

The vascular endothelium is a dynamic endocrine organ that regulates contractile, secretory, and mitogenic activities in the vessel wall and hemostatic processes within the vascular lumen. Risk factors for cardiovascular disease, such as cigarette smoking, hypertension, and elevated serum lipid levels, impair endothelial function and lead to the development of atherosclerotic vessels. Recent studies suggest that statins reduce cardiovascular events in part by improving endothelial function. Statins reduce plasma cholesterol levels, thereby decreasing the uptake of modified lipoproteins by vascular wall cells. There is increasing evidence, however, that statins may also exert effects beyond cholesterol lowering. Indeed, many of these cholesterol-independent or "pleiotropic" vascular effects of statins appear to involve restoring or improving endothelial function through increasing the bioavailability of nitric oxide, promoting re-endothelialization, reducing oxidative stress, and inhibiting inflammatory responses. Thus, the endothelium-dependent effects of statins are thought to contribute to many of the beneficial effects of statin therapy in cardiovascular disease.

Effect of dietary intervention and lipid-lowering treatment on brachial vasoreactivity in patients with ischemic heart disease and hypercholesterolemia

BACKGROUND

The "Mediterranean" diet and statin treatment have both independently been shown to improve survival and reduce the risk of cardiovascular events in patients with ischemic heart disease (IHD), but no studies have evaluated the effect of this combination on endothelial function. We therefore sought to evaluate the effect of the combination dietary intervention and lipid-lowering treatment on brachial vasoreactivity.

METHODS

A total of 131 consecutive patients with documented IHD and a serum cholesterol level > or =5 mmol/L (193 mg/dL) were randomized to receive Mediterranean dietary advice (n = 68) or no specific dietary advice (n = 63). Endothelial function was assessed at baseline and after 12 months with noninvasive ultrasound scanning vessel-wall tracking of brachial artery flow-mediated vasodilatation (FMD). All patients started statin treatment with Fluvastatin (40 mg once daily) at baseline.

RESULTS

A total of 115 patients completed the study. At baseline, FMD was 4.30% +/- 4.89% in the control group versus 4.32% +/- 6.15% in the intervention group (P = not significant). After 12 months of follow-up, FMD was significantly higher in the intervention group (control group 5.72% +/- 4.87% vs intervention group 8.62% +/- 6.60%, P <.01). This was accompanied by a larger intake of fatty fish and a significant decrease in triglyceride levels. In multivariate analysis, randomization status was a significant predictor of FMD after adjustment for classic cardiovascular risk factors and vessel size (P =.02; beta = -2.66 [-4.91; -0.41]).

CONCLUSION

Dietary intervention with the Mediterranean diet and statin treatment improve FMD in the brachial artery in patients with IHD and hypercholesterolemia to a greater degree than statin treatment alone.

Smoking and endothelial function

The arterial endothelium is a vital homeostatic cell layer responsible for a variety of functions such as thromboresistance, control of vessel tone, and vessel growth. Recent evidence has indicated that both active and passive cigarette smoking are associated with dysfunction of normal endothelial physiology, in a dose dependent and potentially reversible way. Endothelial abnormalities may predispose to the atherogenic and thrombotic problems associated with cigarette smoking.

Comparison of forearm endothelial function between premenopausal and postmenopausal women with or without hypercholesterolemia

We sought to determine whether menopausal status or postmenopausal hypercholesterolemia affects forearm resistance artery endothelial function. We studied the forearm resistance artery endothelial function in 75 Japanese women: 25 premenopausal volunteers, 25 postmenopausal women with normal serum low-density lipoprotein (LDL) cholesterol concentrations, and 25 hypercholesterolemic postmenopausal women. Excluded from the study were patients with hypertriglyceridemia, hypertension, or diabetes, cigarette smokers. The forearm blood flow (FBF) during reactive hyperemia and after sublingual nitroglycerin (NTG) administration was measured by strain-gauge plethysmography. The serum concentrations of lipoprotein (a) [Lp(a)] were significantly higher in the hypercholesterolemic postmenopausal group than in the other two groups (P<0.01). These lipid parameters were similar between the premenopausal and postmenopausal women with normal cholesterol. The FBF responses to reactive hyperemia were significantly lower in the postmenopausal hypercholesterolemic women than in the other two groups (P<0.01). The reactive hyperemia also was impaired in the postmenopausal group with normal cholesterol as compared with the premenopausal group (P<0.01). Increases in FBF after NTG were similar between the three groups. By stepwise multivariate analysis, menopausal status and serum LDL cholesterol was the significant predictor of forearm endothelial function. These findings suggest that reactive hyperemia is impaired in forearm resistance arteries after menopause, especially in postmenopausal women with hypercholesterolemia.

A randomized trial of aggressive lipid reduction for improvement of myocardial ischemia, symptom status, and vascular function in patients with coronary artery disease not amenable to intervention

PURPOSE

To determine the effects of aggressive lipid lowering on markers of ischemia, resistance vessel function, atherosclerotic burden, and symptom status in patients with symptomatic coronary artery disease.

METHODS

Sixty consecutive patients with coronary artery disease that was unsuitable for revascularization were assigned randomly to either usual therapy of lipids for patients with a low-density lipoprotein (LDL) cholesterol target level <116 mg/dL, or to a more aggressive lipid-lowering strategy involving up to 80 mg/d of atorvastatin, with a target LDL cholesterol level <77 mg/dL. The extent and severity of inducible ischemia (by dobutamine echocardiography), vascular function (brachial artery reactivity), atheroma burden (carotid intima-media thickness), and symptom status were evaluated blindly at baseline and after 12 weeks of treatment.

RESULTS

After 12 weeks of treatment, patients in the aggressive therapy group had a significantly greater decrease in mean (+/- SD) LDL cholesterol level than those in the usual care group (29 +/- 38 mg/dL vs. 7 +/- 24 mg/dL, P = 0.03). Patients in the aggressive therapy group had a reduction in the number of ischemic wall segments (mean between-group difference of 1.3; 95% confidence interval: 0.1 to 2.0; P = 0.04), flow-mediated dilatation (mean between-group difference of 5.9%; 95% confidence interval: 2.5% to 9.4%; P = 0.001), and angina score after 12 weeks. There were no significant changes in atherosclerotic burden in either group.

CONCLUSION

Patients with symptomatic coronary artery disease who are treated with aggressive lipid lowering have improvement of symptom status and ischemia that appears to reflect improved vascular function but not atheroma burden.

Oxidative stress and endothelial nitric oxide bioactivity

The endothelium plays an important role in the maintenance of vascular homeostasis. Central to this role is the endothelial production of nitric oxide (NO), synthesized by the constitutively expressed endothelial isoform of nitric oxide synthase. Vascular diseases, including hypertension, diabetes, and atherosclerosis, are characterized by impaired endothelium-derived NO bioactivity that may contribute to clinical cardiovascular events. Growing evidence indicates that impaired endothelium-derived NO bioactivity is due, in part, to excess vascular oxidative stress. This review outlines how different forms of oxidative stress can impact on NO bioactivity and discusses strategies to prevent oxidative stress-induced endothelial dysfunction.