Cardiovascular benefit of cholesterol-lowering therapy: does improved endothelial vasodilator function matter?

Novel Aspects Targeting Platelets in Atherosclerotic Cardiovascular Disease—A Translational Perspective

Platelets are important cellular targets in cardiovascular disease. Based on insights from basic science, translational approaches and clinical studies, a distinguished anti-platelet drug treatment regimen for cardiovascular patients could be established. Furthermore, platelets are increasingly considered as cells mediating effects “beyond thrombosis”, including vascular inflammation, tissue remodeling and healing of vascular and tissue lesions. This review has its focus on the functions and interactions of platelets with potential translational and clinical relevance. The role of platelets for the development of atherosclerosis and therapeutic modalities for primary and secondary prevention of atherosclerotic disease are addressed. Furthermore, novel therapeutic options for inhibiting platelet function and the use of platelets in regenerative medicine are considered.

Effect of mild endurance exercise training and pravastatin on peripheral vasodilatation of forearm resistance vessels in patients with coronary artery disease

Background Improved endothelial function may contribute to the beneficial effects of cholesterol lowering therapy in patients with coronary artery disease (CAD), but results of the effect of statin therapy on endothelial function are disparate in these patients. Exercise training has been reported to improve endothelial function of patients at risk of or with established CAD. The goal of the study was to compare the effect of mild exercise training or statin therapy on forearm endothelial function in CAD patients with average cholesterol levels.

Design and methods Twenty-eight sedentary male patients with angiographically documented CAD and average pretreatment total plasma cholesterol levels (5.1±0.9 mmol/l) aged 42–75 years were included. They were randomly assigned in a 2:1 order to either statin therapy (pravastatin, 40 mg daily) or exercise training therapy (mild endurance exercise three or more times a week). The effects of 10 weeks of either treatment on endothelium-dependent and independent vasodilation of forearm resistance vessels was assessed by plethysmography. Cardiopulmonary exercise testing was performed at baseline and after 10 weeks.

Results Ten weeks of pravastatin therapy significantly reduced low-density lipoprotein cholesterol (from 3.8±0.6 to 3.1±0.6 mmol/l at study end, P=0.04) and the ratio of total to high-density lipoprotein cholesterol (from 4.9±0.8 to 3.7±0.7 mmol/l, P=0.002). Exercise training did not significantly modify the lipid profile. Peak oxygen consumption, maximal achieved workload and exercise duration tended to improve in the exercise training group but remained unchanged in the pravastatin-treated group. Neither 10 weeks of pravastatin nor mild endurance exercise training improved endothelium-dependent or independent vasomotor function in forearm resistance vessels.

Conclusions In patients with CAD and average cholesterol levels, 10 weeks of treatment with mild endurance exercise training or with pravastatin failed to improve endothelium-dependent or independent vasomotor function in forearm resistance vessels.

Prognostic role of brachial reactivity in patients with ST myocardial infarction after percutaneous coronary intervention

OBJECTIVE

We hypothesized that flow-mediated vasodilation (FMD) in the brachial artery as a noninvasive method is of value in providing further predictive insights in a cohort of patients with ST-segment elevation acute myocardial infarction (STEMI) after percutaneous coronary intervention (PCI).

METHODS AND RESULTS

One hundred and one patients (62.43+/-9.06, 67 men) with STEMI, undergoing successful primary and rescue PCI, were included in this study. FMDs of all patients were determined using ultrasound after PCI. Patients were tracked for subsequent cardiovascular events. Twenty-nine patients had an event during 12.1+/-2.6 months of follow-up. Multivariate Cox proportional hazard analysis identified a diagnosis of diabetes [hazard ratio (HR): 2.934, 95% confidence interval (CI): 1.314-6.548, P=0.0086], ejection fraction (HR: 0.900, 95% CI: 0.832-0.973, P=0.0082), and FMD (HR: 0.705, 95% CI: 0.573-0.868, P=0.0010) after adjustment of all entered baseline variables. ROC analysis showed that FMD (ROC area: 0.689, P=0.0012; optimal threshold: 5.5% or less) had predictive value with sensitivity of 64%, specificity of 61%, positive predictive value of 40%, and negative predictive value of 81%.

CONCLUSION

In patients with STEMI, early evaluation of endothelial function after PCI could help to shed light on the mechanisms that increase the risk of new events. FMD could be used as a surrogate marker of events.

ORIGINAL RESEARCH—ED PHARMACOTHERAPY: Can Atorvastatin Improve the Response to Sildenafil in Men with Erectile Dysfunction Not Initially Responsive to Sildenafil? Hypothesis and Pilot Trial Results

BACKGROUND

Erectile dysfunction (ED) may be one manifestation of a generalized vascular disorder characterized by endothelial dysfunction. Statin drugs may improve endothelial function, even before altering the lipid profile.

OBJECTIVE

We sought to determine whether the addition of a statin with sildenafil would improve ED in men who initially responded poorly to sildenafil.

METHODS

Men with moderate-to-severe ED despite an adequate sildenafil trial were enrolled in this randomized, double-blind, placebo-controlled pilot study. ED was defined using a validated self-administered questionnaire as a score of <or=16 on the International Index of Erectile Function (erectile function domain score range of 6-30). Improvement in ED score with sildenafil was reassessed at 6 and 12 weeks of treatment with atorvastatin (80 mg daily) or matching placebo.

RESULTS

Twelve men (mean age 58 +/- 13 years) with a mean domain score of 8.2 +/- 6.9 and a mean duration of ED of 3.7 years were enrolled in the study. Treatment with atorvastatin decreased mean low-density lipoprotein cholesterol by 43% and resulted in an improvement with sildenafil in domain score of 7.8 (P = 0.036); an effect was apparent by 6 weeks. The increase in domain score in placebo patients was not statistically significant.

CONCLUSIONS

Treatment with atorvastatin improved sexual function and the response to oral sildenafil in men who did not initially respond to treatment with sildenafil. The results of this pilot study support the hypothesis that vascular endothelial dysfunction contributes to ED in sildenafil nonresponders and deserves further testing in a large clinical trial.

Platelets, Inflammation, and Atherothrombotic Neurovascular Disease: The Role of Endothelial Dysfunction

The vascular endothelium is an indispensable organ in the regulation of tonicity and vascular homeostasis. Endothelial dysfunction is a marker of atherosclerosis and contributes to the atherogenic process and the development of atherothrombotic complications. Endothelial dysfunction is the common meeting point among factors for vascular risk and launches complex cellular and biochemical interactions that are characterized by oxidative stress and an intense inflammatory response. The strategic importance of the concept of endothelial dysfunction arises from the following facts: its diagnosis is simple, it allows the identification of asymptomatic arteriosclerotic subjects with a high risk of developing atherothrombotic complications, it is reversible, and it responds to various therapeutic strategies.

Endothelial Vasomotor Dysfunction in the Brachial Artery Is Associated With Late In-Stent Coronary Restenosis

OBJECTIVES

This study examined whether endothelial dysfunction in the brachial artery might be associated with late in-stent restenosis (ISR) after percutaneous coronary intervention (PCI).

BACKGROUND

Simple and noninvasive identification of late ISR might help to select patients who require further angiographic evaluation.

METHODS

Endothelium-dependent flow-mediated dilation (FMD) of the brachial artery was measured before (initial FMD) and at six months (follow-up FMD) after PCI in 141 consecutive patients who had elective and successful PCI with bare metal stents in de novo lesions of native coronary arteries for symptomatic coronary artery disease. Follow-up angiography was performed at six months after PCI in all patients.

RESULTS

With multivariate logistic regression analysis, the impairment (< or = 4.8% dilation from baseline diameter) of FMD at follow-up showed the strongest association with late ISR (defined as > 50% diameter stenosis, n = 46) independently of other clinical and angiographic variables known to be associated with ISR (odds ratio 7.4, 95% confidence interval 2.8 to 19.2, p < 0.001), whereas the initial FMD did not have the association. The sensitivity of impaired FMD at follow-up (69%) in detecting ISR was higher than chest pain during the follow-up period (45%), with comparable specificity. The impaired FMD in combination with the chest pain increased the sensitivity to 90%.

CONCLUSIONS

The impairment of FMD in the brachial artery at the time of follow-up was independently and closely associated with late ISR in native coronary arteries. The noninvasive assessment of FMD at the time of follow-up might be useful for identification of late ISR.

The effects of LDL reduction and HDL augmentation on physiologic and inflammatory markers

Cholesterol plays an important role in atherogenesis. Oxidized low-density lipoprotein cholesterol is harmful to arteries whereas high-density lipoprotein cholesterol appears to have beneficial properties on vascular function. There is increasing evidence that inflammation is also involved in the atherogenic process. Inflammation accelerates atherosclerosis and promotes thrombogenesis, and inflammatory biomarkers have been correlated with cardiovascular risk. There is now evidence that lowering low-density lipoprotein and raising high-density lipoprotein cholesterol have beneficial effects on inflammation that might contribute to the reduction in clinical cardiovascular events with currently available lipid-altering therapies. New therapeutic strategies are being designed to inhibit specific aspects of the inflammatory system that contribute to the initiation and progression of atherosclerosis.

Aggressive lipid lowering does not improve endothelial function in type 2 diabetes: the Diabetes Atorvastatin Lipid Intervention (DALI) Study: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

Endothelial dysfunction is considered an important early marker of atherosclerosis and cardiovascular risk and is currently used as a surrogate end point for cardiovascular risk in clinical trials. Type 2 diabetic patients show a characteristic dyslipidemia. Aggressive lipid lowering might be an effective method to improve endothelial function in these patients.

RESEARCH DESIGN AND METHODS

A randomized, double-blind, placebo-controlled trial was completed to study the effect of 30 weeks' administration of atorvastatin 10 mg and 80 mg on endothelial function, as assessed by B-mode ultrasound of the brachial artery, in 133 patients with type 2 diabetes without a history of cardiovascular disease.

RESULTS

Patients with diabetes and diabetic dyslipidemia had considerable endothelium-dependent and endothelium-independent dysfunction; mean flow-mediated vasodilation (SD) was 3.16% (3.56), and mean response on sublingual nitroglycerin was 6.58% (6.04). Despite substantial lowering of all atherogenic lipid parameters, no improvement of endothelium-dependent vasodilatation was found (P > 0.8).

CONCLUSIONS

We observed considerable baseline endothelium-dependent and endothelium-independent dysfunction in patients with diabetes and diabetic dyslipidemia without a history of cardiovascular disease. Aggressive lipid lowering by administration of atorvastatin, resulting in substantial improvement of the lipid profile, did not reverse endothelial dysfunction.

Pleiotropic effects of statins: do they matter?

Treatment with the 3-hydroxy-3-methylglutaryl coenyzme A reductase inhibitors (or statins) reduces the risk for cardiovascular events across a broad spectrum of patient profiles, as evidenced by both primary prevention and secondary prevention trials. Improved survival by way of reduced deaths from coronary heart disease was also reported with these agents, which are primarily indicated for substantial reduction in LDL-cholesterol levels. However, the statins are extremely complex drugs and exhibit a wide variety of vascular effects that may or may not be dependent on their lipid-modifying properties. These so-called pleiotropic effects include alterations of endothelial function, inflammation, coagulation, and plaque stability. The relative contribution of the nonlipid effects of statin therapy to the well-documented clinical benefits is currently under intense investigation.

Pluripotential mechanisms of cardioprotection with HMG-CoA reductase inhibitor therapy

Treatment with hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors has been accompanied by a reduced risk of cardiovascular events. Rapid onset of clinical benefit and weak correlations between plasma low density lipoprotein-cholesterol levels and coronary lumen change or cardiovascular events indicates that nonlipid mechanisms are involved in this beneficial effects with HMG-CoA reductase inhibitors. Furthermore, more rapid onset of clinical benefit with HMG-CoA reductase inhibitors in patients with acute coronary syndromes or acute myocardial infarction than in those with stable coronary heart disease suggest that HMG-CoA reductase inhibitors facilitate repair of ruptured or ulcerated atherosclerotic plaque, facilitate plaque stabilization and/or reduce thrombus formation on ruptured plaques. Treatment with HMG-CoA reductase inhibitors improved endothelial dysfunction in patients with hypercholesterolemia and this improvement in endothelial function was not correlated with reduction in total serum cholesterol levels. Similarly, reduction in endothelial pre-proendothelin mRNA expression and endothelin synthesis and blood pressure lowering with HMG-CoA reductase inhibitors occurred independent of lipid-lowering. Finally, HMG-CoA reductase inhibitors increased endothelial nitric oxide levels i.e. upregulated endothelial nitric oxide synthetase expression via post-transcriptional mechanisms and prevented its down-regulation by oxidized LDL-C. HMG-CoA reductase inhibitors have been shown to modulate the immune response by inhibiting activation of immune-competent cells such as macrophages, and antigen presentation to macrophages by T cells. Treatment with HMG-CoA reductase inhibitors can reduce expression, production and circulating levels of chemokines (monocyte chemoattractant protein-1) and proinflammatory cytokines [tumor necrosis factoralpha, interleukin (IL)-6 and IL-1beta]. HMG-CoA reductase inhibitors reduced inflammation in human atheroma: significantly fewer macrophages and T cells, less oxidized LDL-C and higher collagen content. In addition, treatment with HMG-CoA reductase inhibitor led to decreased cell death within the atheroma. Treatment with these agents also reduced expression of inducible cellular adhesion molecules, decreased secretion of metalloproteinases by macrophages, reduced vascular smooth muscle cell apoptosis. Lastly, HMG-CoA reductase inhibitors appear to have important effects on the thrombogenesis: reduced expression of tissue factor production and activity; increased production of tissue factor package inhibitor; decreased platelet thrombus formation and improved fibrinolysis as a result of lowered plasminogen activator inhibitor-1 levels. As the pluripotential cardioprotective mechanisms of HMG-CoA reductase inhibitors are further elucidated, it is envisaged that treatment with HMG-CoA reductase inhibitors will be initiated earlier and more frequently in patients with hypercholesterolemia.