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

Modulatory role of lipoprotein oxidation on platelet-vessel wall interactions

Oxidation of plasma lipoproteins may play an important role in atherogenesis, but there are also indications that that this process of oxidation may influence other facets of cardiovascular disease, namely blood flow and thrombosis. The evidence that oxidation of low-density lipoproteins may modulate the action of the native lipoproteins with respect to endothelium-dependent relaxation, platelet activation and tissue factor activity is reviewed.

[Conservative therapeutic approaches in terminal coronary heart disease. Chronic intermittent urokinase therapy]

Despite progress in the invasive revascularization procedures and even though conventional antianginal treatment has improved the quality of life in patients with symptomatic coronary artery disease considerably, an increasing number of patients suffers from end-stage coronary artery disease and refractory angina pectoris. For these refractory patients long-term intermittent urokinase therapy was developed as an antithrombotic intervention, which is based on its capacity to enhance thrombolysis and blood rheology, and may possibly lead to plaque regression. The coronary syndrome of refractory angina pectoris is characterized by a mismatch of severe coronary insufficiency and a relatively large amount of viable myocardium as indicated by an only moderately impaired left ventricular function. Prior to initiation of long-term intermittent urokinase therapy all potential measures to improve myocardial perfusion have to be considered in each patient. These supportive measures include rigorous reduction of LDL-cholesterol, which has proven antiischemic properties due to an improved endothelial function of epicardial conductance vessels possibly resulting in an antianginal effect. Apart from the proven antiischemic properties of long-term intermittent urokinase therapy in patients with refractory angina pectoris, objective signs of ischemic myocardial heart failure improve. Follow-up studies demonstrated a significant increase of left ventricular ejection fraction as evaluated with multi-gated blood pool analysis. Furthermore, left ventricular diastolic function normalized after a treatment period of 12 weeks. As the clinical effects last well beyond the actual treatment period and as they are accompanied by a remarkable increase in the quality of life, a complex approach as this one is justified in this highly symptomatic patient group.

Hypertension, aging, and atherosclerosis. The endothelial interface

Hypertension, atherosclerosis, and aging are considered major independent risk factors for cardiovascular morbidity and mortality. Although independent as risk factors, the three entities are closely related and often operate simultaneously to affect the cardiovascular system adversely, resulting in damage to various organs. This article evaluates the evidence that endothelial damage may be the underlying pathophysiologic mechanism that connects the three entities.

Dietary L-arginine reduces the progression of atherosclerosis in cholesterol-fed rabbits: comparison with lovastatin

BACKGROUND

We investigated whether L-arginine induces regression of preexisting atheromatous lesions and reversal of endothelial dysfunction in hypercholesterolemic rabbits, whether similar effects can be obtained by cholesterol-lowering therapy with lovastatin, and which mechanism leads to these effects.

METHODS AND RESULTS

Rabbits were fed 1% cholesterol for 4 weeks and 0.5% cholesterol for an additional 12 weeks. Two groups of cholesterol-fed rabbits were treated with L-arginine (2.0% in drinking water) or lovastatin (10 mg/d) during weeks 5 through 16. Systemic nitric oxide (NO) formation was assessed as the urinary excretion rates of nitrate and cGMP in weekly intervals. Cholesterol feeding progressively reduced urinary nitrate excretion to approximately 40% of baseline (P<.05) and increased plasma concentrations of asymmetrical dimethylarginine (ADMA), an endogenous NO synthesis inhibitor. Dietary L-arginine reversed the reduction in plasma L-arginine/ADMA ratio and partly restored urinary excretion of nitrate and cGMP (each P<.05 vs cholesterol) but did not change plasma cholesterol levels. L-Arginine completely blocked the progression of carotid intimal plaques, reduced aortic intimal thickening, and preserved endothelium-dependent vasodilator function. Lovastatin treatment reduced plasma cholesterol by 32% but did not improve urinary nitrate or cGMP excretion or endothelium-dependent vasodilation. Lovastatin had a weaker inhibitory effect on carotid plaque formation and aortic intimal thickening than L-arginine. L-Arginine inhibited but lovastatin potentiated superoxide radical generation in the atherosclerotic vascular wall.

CONCLUSIONS

Dietary L-arginine improves NO-dependent vasodilator function in cholesterol-fed rabbits and completely blocks the progression of plaques via restoration of NO synthase substrate availability and reduction of vascular oxidative stress. Lovastatin treatment has a weaker inhibitory effect on the progression of atherosclerosis and no effect on vascular NO elaboration, which may be due to its stimulatory effect on vascular superoxide radical generation.

Effects of nitric oxide and superoxide on relaxation in human artery and vein

Endothelium-derived relaxing and contracting factors play an important role in atherosclerosis, re-stenosis and graft survival. Internal thoracic artery (ITA) and saphenous vein (SV) are used as conduit vessels in coronary artery bypass graft surgery (CABG). The long-term graft patency rate is higher with ITA than SV. Effects of nitric oxide and superoxide on vascular relaxation in isolated rings of ITA and SV from patients undergoing CABG were investigated. NG-nitro-L-Argenine methylester (L-NAME) was used to block nitric oxide synthesis and superoxide dismutase (SOD) and tiron to scavenge superoxide. Responses to carbachol were taken as a measure of stimulated nitric oxide release and increased responses to phenylephrine after addition of L-NAME as a measure of basal nitric oxide release. Immunocytochemical demonstration of endothelial nitric oxide synthase was performed using anti-endothelial nitric oxide synthetase (anti-eNOS) NOS antibody. Stimulated nitric oxide release was observed in ITA and SV but basal release was reduced or absent in SV. Treatment with SOD and tiron potentiated carbachol stimulated relaxation in ITA and SV. Tiron treatment resulted in a significant increase in basal nitric oxide in veins. eNOS immunoreactivity was more intense in ITA than SV, compatible with reduced nitric oxide production in veins. This may contribute to the reduced patency of venous grafts.

The retardation of progression, stabilization, and regression of coronary and carotid atherosclerosis by low-density lipoprotein apheresis in patients with familial hypercholesterolemia

The long-term effects of low-density lipoprotein (LDL) apheresis (LA) on the progression and regression of atherosclerosis were evaluated by angiographic and pathological findings as well as ultrasonography based studies, and the clinical significance of the treatment was evaluated. We studied 11 patients with familial hypercholesterolemia (FH), 2 with homozygous FH and 9 with severe heterozygous FH who received combined LA and drug therapy for a mean of 7.7 years. During the treatment period, the mean time-averaged level of LDL cholesterol was 181+/-52 mg/dl. According to the coronary angiographic results, 3 patients showed regression, 6 patients showed progression, and 2 patients showed no change. Cardiac events occurred in 6 patients. We pathologically examined at autopsy the coronary arteries of 1 FH patient who had received long-term LA therapy before death. The results revealed the process of scarring of atheromatous plaque, suggesting pathological regression correlated with the angiographic regression shown in serial angiograms taken during LA treatment. It was further suggested that the formation of an eccentric thick end wall lesion rich in collagen fiber prevented atheromatous plaque from tearing off. However, the annual progression rate of the mean maximal intima-media thickness in the common carotid artery was 0.0002 mm/year in the LA group, which was significantly lower than the mean of 0.251 mm/year seen in the control group (drug therapy only group). In the patients with heterozygous FH (9 patients), the annual progression rate was lowered to 0.0023 mm/year, suggesting regression. The findings of the present study indicate that patients with severe FH refractory to drug treatment may benefit from more aggressive cholesterol lowering treatments such as LA combined with cholesterol lowering drug therapy. The progression of atherosclerosis may be prevented, plaque may be stabilized (regressed), and clinical events may be reduced as seen with patients with non-FH hypercholesterolemia.

Endothelial dysfunction: does it matter? Is it reversible?

Until recently, the endothelium was regarded as a relatively inert cell layer. However, over the past 20 years, research has revealed an extraordinary array of endothelial functions, including control over coagulation, fibrinolysis, arterial tone and vascular growth. Importantly, endothelial dysfunction has been implicated as a key event in the pathogenesis of atherosclerosis, coronary vasoconstriction and, probably, myocardial ischemia. The recent demonstration that endothelial dysfunction may be reversible raises the possibility of slowing the progression of atherosclerosis or modifying arterial function, or both, to decrease the risk of acute cardiovascular events.

Functional evaluation of lipid-lowering therapy by pravastatin in the Regression Growth Evaluation Statin Study (REGRESS)

BACKGROUND

Lipid-lowering therapy during 2 years in the Regression Growth Evaluation Statin Study (REGRESS) was associated with less progression of coronary atherosclerosis in the pravastatin group compared with the placebo group. The effect of lipid-lowering therapy on the functional state of the coronary circulation is less well known. The purpose of this study was to evaluate this effect.

METHODS AND RESULTS

In a substudy of REGRESS, 69 patients were randomized to pravastatin or placebo. Thirty-seven of these patients were allocated to the medical management stratum. Quantitative coronary angiography, regional myocardial perfusion, exercise testing, and classification of angina pectoris were assessed at baseline and after 2 years of therapy. Regional myocardial perfusion was assessed by digital subtraction angiography after intracoronary papaverine with video-densitometric calculation of the hyperemic mean transit time (HMTT) of contrast. In the medical management stratum, regional myocardial perfusion was assessed in 31 regions in the pravastatin group and 25 regions in the placebo group. The change in HMTT in the pravastatin group was -0.18 seconds (-5%) and in the placebo group +0.52 seconds (+18%), a difference of 0.70 seconds (P=.004). The mean difference in change in classification of angina pectoris (scale, 1 to 4) between pravastatin and placebo was 0.7 (P=.03) in favor of the pravastatin-treated patients. The change in HMTT was correlated with the change in exercise time (r=-.65, P=.002).

CONCLUSIONS

In patients with symptomatic coronary artery disease, treatment with the HMG-coenzyme A reductase inhibitor pravastatin during 2 years resulted in a preserved regional myocardial perfusion, whereas patients on placebo deteriorated. The classification of angina pectoris improved only in patients receiving pravastatin. In lipid-lowering therapy, the evaluation of myocardial perfusion by assessment of the HMTT reveals a combined measure of functional and structural changes in the coronary circulation.

Relation of pacing-induced coronary resistance vessel dilation to total serum cholesterol and heart rate-blood pressure product

Coronary risk factors adversely affect coronary resistance vessel dilation to acetylcholine, but little is known about the effect of risk factors on coronary blood flow (CBF) responses to physiologic stimuli. CBF was derived from Doppler flow velocity (0.018-inch Doppler wire) and coronary diameter (quantitative angiography) in response to rapid atrial pacing in 50 patients (mean age 52 +/- 12 years). Patients were prospectively divided into 3 groups based on their angiograms: group 1 (n = 17), normal coronary arteries; group 2 (n = 18), 1-vessel coronary artery disease (CAD) with a smooth study artery; group 3 (n = 15), 1-vessel CAD and an irregular study artery (<20% stenosis). Pacing produced a significant increase in CBF compared with baseline in groups 1 and 2 (34 +/- 40%, 42 +/- 35%, p < 0.0001), respectively, but not in group 3 (21 +/- 33%), but there was no difference in the pacing response among the 3 groups. The increase in CBF to pacing was inversely related to serum cholesterol (p = 0.01) and triglycerides (p = 0.06) and directly related to the increase in heart rate-blood pressure product (p = 0.007). By multivariate analysis, total cholesterol and the increase in double product were the only factors related to the increase in CBF. Increases in CBF to atrial pacing are inversely related to serum total cholesterol and are not related to the angiographic presence of atherosclerosis in patients with mild CAD.

Role of endothelial dysfunction in coronary artery disease

The vascular endothelium plays an essential role in regulating blood flow and other functions of the coronary arteries. Under normal conditions, the endothelium releases a number of factors that regulate arterial vasomotion. One of these factors, endothelial-derived relaxing factor (EDRF), is a vasorelaxant that is identical to, or closely related to, nitric oxide (NO). Endothelial function may be compromised in coronary artery disease (CAD) or in the presence of risk factors for CAD. In this setting, EDRF-NO activity is inhibited, which may lead to vasoconstriction, platelet aggregation, vasospasm, and thrombosis. The relation between endothelial function, arterial vasomotion, and myocardial ischemia is discussed, with particular emphasis on the role of EDRF-NO, and the therapeutic interventions that may be useful in treating the clinical consequences of endothelial dysfunction.

Management of patients with chronic stable angina at low risk for serious cardiac events

Successful management of the patient with chronic stable angina requires correct stratification by assessing the risk of future coronary events. Patients at low risk for such events have a relatively good prognosis; revascularization procedures (balloon angioplasty or surgery) offer no benefit over medical management. Such patients should be offered medical therapy as their first option. The goals in management of chronic stable angina are (1) treatment of other conditions that may worsen angina; (2) treatment with aspirin and modification of risk factors for coronary artery disease (CAD) to improve outcome; and (3) effective relief of anginal symptoms. Most patients with stable angina will have CAD. It is well established that treatment with aspirin and modification of risk factors for CAD are beneficial in reducing cardiovascular mortality and morbidity. Blood pressure reduction, lowering of blood cholesterol level, and smoking cessation are interventions of proven value and appear to correct defects (at least partially) in the endothelial function of the coronary blood vessels. Other interventions that are helpful are estrogen replacement treatment in postmenopausal women, and low-dose aspirin therapy-which is recommended for all patients who can tolerate it. For controlling symptoms and improving angina-free walking time, nitrates, beta blockers, and calcium channel antagonists are efficacious as first-line monotherapy for chronic stable angina in this group of patients. Nitrates may be of special use in patients with impaired left ventricular function, overt congestive heart failure, intermittent coronary vasoconstriction, or coronary artery spasm. In patients with concomitant hypertension or supraventricular tachycardia, beta blockers are helpful. Calcium channel antagonists may be useful in patients with chronic obstructive pulmonary disease, peripheral vascular disease, or hypertension. When optimal monotherapy with a given class of drug fails to control symptoms, alternative monotherapy with a different class of agent should be tried before combination therapy. Combination therapy with 2 or 3 agents is not always superior to optimal monotherapy. Patients who fail to respond to adequate medical therapy should be considered for a revascularization procedure.

Results of recent large cholesterol-lowering trials and implications for clinical management

Three recent large clinical trials-the West of Scotland Coronary Prevention Study, the Scandinavian Simvastatin Survival Study, and the Cholesterol and Recurrent Events Trial-have all confirmed that cholesterol lowering with HMG-CoA reductase inhibitors is safe and effective therapy to prevent an initial or recurrent coronary event in patients at high risk for coronary heart disease. However, a number of questions related to the treatment of lipid disorders and risk reduction for coronary heart disease remain, including the cholesterol concentration at which treatment would best be initiated, the optimal cholesterol reduction or goal to be attained, and the mechanisms by which HMG-CoA reductase inhibitors reduce the risk for clinical events.

Should we treat hypercholesterolaemia in patients over 65?

Images

The physiology and pathophysiology of the nitric oxide/superoxide system

The endothelium modulates vascular tone by producing vasodilator vasoconstrictor substances. Of these, the most well characterized and potentially important are .NO and .02-. These small molecules exhibit opposing effects on vascular tone, and chemically react with each other in a fashion which negates their individual effects and leads to the production of potentially toxic substances. These dynamic interactions may likely have important implications, altering not only tissue perfusion but also contributing to the process of atherosclerosis. .NO is produced in endothelial cells by an enzyme termed nitric oxide synthase. The endothelial .NO-synthase is activated when the intracellular level of calcium is increased. This occurs in response to neurohormonal stimuli and in response to shear stress. Acetylcholine and substance P are examples of neurohumoral substances that are able to stimulate the release of nitric oxide and to assess endothelial regulation of vasomotor tone. Importantly, the vasodilator potency of nitric oxide released by the endothelium is abnormal in a variety of diseased states such as hypercholesterolemia, atherosclerosis and diabetes mellitus. This may be secondary to decreased synthesis of nitric oxide or increased degradation of nitric oxide due to superoxide anions. More recent experimental observations demonstrate increased production of superoxide in atherosclerosis, diabetes mellitus and high renin hypertension suggesting that endothelial dysfunction in these states is rather secondary to increased .NO metabolism rather than due to decreased synthesis of .NO. Superoxide rapidly reacts with nitric oxide to form the highly reactive intermediate peroxynitrite (ONOO-). Peroxynitrite can be protonated to form peroxynitrous acid which in turn can yield the hydroxyl radical (OH.). These reactive species can oxidize lipids, damage cell membranes, and oxidize thiol groups. .NO given locally, exerts potent antiatherosclerotic effects such as inhibition of platelet aggregation, inhibition of adhesion of leukocytes and the expression of leukocyte adhesion molecules. It is important to note, however, that in-vivo treatment with .NO (via organic nitrates) increases rather than decreases oxidant load within endothelial cells. It remains therefore questionable whether systemic treatment with .NO may have antiatherosclerotic properties or whether .NO may initiate or even accelerate the atherosclerotic process.

Angiotensinogen gene variation associated with variation in blood pressure in aboriginal Canadians

We measured blood pressure and related clinical phenotypes in 497 adult native Canadians from an isolated community in Northern Ontario. We analyzed their DNA for genotypes of angiotensinogen. We found that the frequency of the T235 variant of the angiotensinogen gene was 0.89 in this sample. This variant was associated with a significantly increased systolic pressure but not diastolic pressure. We also found that sex and body mass were each highly significantly associated with variation in both systolic and diastolic pressures. We found a significant association between age and variation in systolic pressure but not diastolic pressure. We also found a highly significant association between plasma apolipoprotein B concentration and variation in diastolic pressure but not systolic pressure. The high frequency of the angiotensinogen T235 variant suggests that subjects in this young, essentially normotensive population might be predisposed to hypertension, which may become more apparent in the presence of secondary factors.

Stroke, statins, and cholesterol. A meta-analysis of randomized, placebo-controlled, double-blind trials with HMG-CoA reductase inhibitors

BACKGROUND AND PURPOSE

To estimate the effect of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors ("statins") on stroke ris, we combined the data of the randomized, placebo-controlled, double-blind trials with HMG-CoA reductase inhibitors published so far.

METHODS

The studies were identified using the Medline CD+ and Current Contents databases from January 1980 through May 1996, inclusive. All studies were evaluated on the use of a placebo control, monotherapy, and double blindness. When the type of stroke or the occurrence of clinical events or adverse effects were incompletely or not reported, the investigators were contacted personally. For each trial, the number of strokes in the treatment arm was compared with the number of strokes expected on all observations under the assumption that drug treatment had no effect.

RESULTS

A total of 462 strokes among 20438 participants in 13 trials could be analyzed. A total of 181 strokes were observed in patients randomized to treatment with an HMG-CoA reductase inhibitor and 261 strokes in patients randomized to placebo. A lower than expected number of strokes was observed in the treatment groups of all but one trial (P = .001). Treatment with an HMG-CoA reductase inhibitor led to an overall risk reduction of 31% (odds ratio, 0.69; 95% confidence interval, 0.57 to 0.83).

CONCLUSIONS

The combined data suggest that treatment with HMG-CoA reductase inhibitors prevents stroke in middle-aged persons. Because stroke is especially common in older age, these data reinforce the need for clinical trials to evaluate the effect of HMG-CoA reductase inhibitors in preventing stroke in the elderly.

Coronary risk factors, endothelial function, and atherosclerosis: a review

The traditional risk factors for coronary heart disease, which include hypercholesterolemia, hypertension, cigarette smoking, diabetes mellitus, and high-fat diet, have all been associated with impairments in endothelial function. Impaired endothelium function may promote the development of atherosclerosis through its effects on vasoregulation, platelet and monocyte adhesion, vascular smooth muscle cell growth, and coagulation. Increased oxidative stress may be another mechanism by which endothelial dysfunction contributes to atherosclerosis, although controversy exists on this issue. Risk factor modification, particularly lowering elevated concentrations of low-density lipoprotein cholesterol, improves endothelial function. At least seven clinical studies have demonstrated improved endothelial function with cholesterol reductions in patients with markedly elevated or even borderline elevations in cholesterol concentrations, whether or not coronary heart disease is present. Other interventions that improve endothelial function include blood pressure reduction, smoking cessation, and administration of estrogen to postmenopausal women.

Coronary risk factors and plaque morphology in men with coronary disease who died suddenly

BACKGROUND

Cigarette smoking and abnormal serum cholesterol concentrations are risk factors for acute coronary syndromes, but the underlying mechanisms are poorly understood. We studied whether cigarette smoking and abnormal cholesterol values may precipitate acute coronary thrombosis and sudden death resulting from either rupture of vulnerable coronary plaques or erosion of plaques.

METHODS

We examined the hearts of 113 men with coronary disease who had died suddenly and also analyzed their coronary risk factors. We found an acute coronary thrombus in each of 59 men, and severe narrowing of the coronary artery by an atherosclerotic plaque without acute thrombosis (stable plaque) in 54. Cases of acute thrombosis were divided into two groups: 41 resulting from rupture of a vulnerable plaque (a thin fibrous cap overlying a lipid-rich core), and 18 resulting from the erosion of a fibrous plaque rich in smooth-muscle cells and proteoglycans. Vulnerable plaques that had not ruptured were counted in each heart.

RESULTS

Cigarette smoking was a risk factor in 44 (75 percent) of the men with acute thrombosis, as compared with 22 (41 percent) of the men with stable plaques (P<0.001). The mean (+/-SD) ratio of serum total cholesterol to high-density lipoprotein (HDL) cholesterol was markedly elevated in the men who died of acute thrombosis with plaque rupture (mean, 8.5+/-4.0) but only mildly elevated in the men without acute thrombosis (5.5+/-2.4; P<0.001) and in the men with thrombi overlying eroded plaques (5.0+/-1.8; P<0.001). Multivariate analysis showed an association between an elevated ratio of serum total cholesterol to HDL cholesterol and the presence of vulnerable plaques (P<0.001).

CONCLUSIONS

Among men with coronary disease who die suddenly, abnormal serum cholesterol concentrations - particularly elevated ratios of total cholesterol to HDL cholesterol - predispose patients to rupture of vulnerable plaques, whereas cigarette smoking predisposes patients to acute thrombosis.

Inhibition of proliferation of human smooth muscle cells by various HMG-CoA reductase inhibitors; comparison with other human cell types

The effects of 6 HMG-CoA reductase inhibitors: pravastatin, lovastatin, simvastatin, atorvastatin, fluvastatin and cerivastatin were analyzed in cultured human smooth muscle cells, fibroblasts, endothelial cells and myoblasts. In vascular smooth muscle cells, pravastatin was a much weaker inhibitor of cholesterol synthesis than the 5 other drugs which displayed equally strong inhibitory potency. The anti-proliferative effects of these 6 drugs were analyzed by measuring cell number and mitochondrial dehydrogenase activity (MTT assay) after 3 days of incubation. IC25 values for inhibition of proliferation were very similar among the 4 cell types and were in the following order of magnitude: pravastatin << lovastatin = simvastatin = atorvastatin = fluvastatin << cerivastatin. Only in the case of pravastatin was proliferation inhibited at lower concentration in smooth muscle cells than in the other cell types. Proliferation was also assessed by measuring DNA synthesis in these cells. A 3 day-incubation with 1 microM of pravastatin had no effect on this parameter in all 4 cell types. However, 1 microM of simvastatin or lovastatin caused either an inhibition (in smooth muscle cells and endothelial cells) or stimulation (in fibroblasts) of this process. The effects of simvastatin on cell number, mitochondrial dehydrogenase activity and DNA synthesis were counteracted by simultaneous mevalonate addition. Simvastatin treatment was also associated with a change in the post-translational modification of the ras protein in smooth muscle cells, probably by inhibition of its farnesylation. Moreover, simvastatin treatment blocked the PDGF and bFGF-induced DNA synthesis in synchronized smooth muscle cells, whereas it does not affect the fetal calf serum-induced DNA synthesis in synchronized fibroblasts, suggesting that simvastatin blocks various steps of the cell cycle and that this effect depends on the cell type and the growth signalling pathway activated.

The efficacy of lovastatin in lowering cholesterol in African Americans with primary hypercholesterolemia

PURPOSE

To evaluate the efficacy of lovastatin in African Americans (AA) diagnosed with primary hypercholesterolemia.

PATIENTS AND METHODS

Forty-seven AA patients from the King/Drew Medical Center in Los Angeles were recruited from the Hypertension, Family Practice, and General Medicine Clinics for a double-blinded, placebo-controlled trial. Forty-one patients completed the 10 week study. Eligibility for entrance into the study was determined by patient lipid profiles meeting the criteria for pharmacological intervention outlined by the National Cholesterol Education Program II guidelines. Patients were randomized into 2 groups: lovastatin 20 mg per day, or placebo. A registered dietitian counseled both groups on two visits during the study to ensure compliance with a low fat, low cholesterol diet. Lipid levels were compared at the first and last visit of the study.

RESULTS

The lovastatin-treated group demonstrated significant reductions in mean total cholesterol (TC) (14.7%, 95% confidence interval [CI]-6.6 to -22.8, P < 0.01) and low-density lipoprotein (LDL) cholesterol (20.0%, 95% CI-7.9 to -32.1, P < 0.01) from baseline. Plasma triglyceride (TG) levels decreased by 10.5% (95% CI-2.4 to -18.6) and total cholesterol/high density lipoprotein (HDL) ratio fell below five in the lovastatin group, but neither reduction reached statistical significance. Placebo administration was not associated with any significant changes in TC, LDL, or TG. There were no significant differences between baseline and post-treatment hepatic transaminase levels in either group.

CONCLUSIONS

The HMG-CoA (3-hydroxyl-3 methylglutary coenzyme A) reductase inhibitor lovastatin in a dose of 20 mg per day was effective in decreasing TC, LDL, and TG levels in an AA population. Considering that the AA population is at substantially increased risk for hypertension and cardiovascular morbidity, more aggressive and wider use of HMG-CoA reductase inhibitors should be employed in reducing elevated plasma cholesterol levels.

Effect of pravastatin (10 mg/day) on progression of coronary atherosclerosis in patients with serum total cholesterol levels from 160 to 220 mg/dl and angiographically documented coronary artery disease. Coronary Artery Regression Study (CARS) Group

To evaluate the effect of pravastatin on progression of coronary atherosclerosis in normocholesterolemic patients with coronary artery disease (CAD), 90 patients with CAD and serum cholesterol levels of 160 to 220 mg/dl were randomized into a pravastatin (10 mg/day) group (n = 45) and control group (n = 45) in a 2-year study. The proportions of patients with progression (an increase of > or = 15% in percent stenosis) and regression (a decrease of > or = 15% in percent stenosis) of coronary atherosclerosis were compared between the 2 groups. Of 90 patients, 80 (89%) had a final angiogram: the pravastatin (n = 39) and control group (n = 41). Percent changes in total cholesterol, low-density lipoprotein cholesterol, and apoprotein B levels were significantly greater in the pravastatin group than in the control group (total cholesterol -11 +/- 12% vs 3 +/- 15%, p < 0.01; low-density lipoprotein cholesterol -18 +/- 16% vs 4 +/- 21%, p < 0.01; apoprotein B -5 +/- 20% vs 6 +/- 20%, p < 0.05). The proportion of patients with progression of coronary atherosclerosis was significantly smaller in the pravastatin group than in the control group (21% vs 49%, p < 0.05). The proportion of patients with disease regression did not differ in the 2 groups (3% vs 2%, p = NS). In conclusion, this study indicates that cholesterol-lowering therapy with pravastatin can prevent the progression of coronary atherosclerosis even in normocholesterolemic patients with established CAD.

Ten-year follow-up results from the Goettingen Risk, Incidence and Prevalence Study (GRIPS). I. Risk factors for myocardial infarction in a cohort of 5790 men

Besides the accepted major risk factors for myocardial infarction (MI), cholesterol, hypertension and smoking, several other variables such as lipoproteins, apolipoproteins, fibrinogen and family history of MI, have been considered, but their usefulness as predictors of MI is controversially discussed. The Göttingen Risk Incidence and Prevalence Study (GRIPS) aimed to evaluate the independent impact of the latter in comparison to the established risk factors. GRIPS is a prospective cohort study, which included 5790 men, aged 40-59.9 years, without cardiovascular disease at baseline. Multivariate logistic regression models for the estimation of the MI risk based on the 10-year follow-up data from 97.4% of the study participants established LDL cholesterol as the strongest predictor of MI. It was followed by family history of MI, Lp(a), age, smoking, systolic blood pressure, HDL cholesterol (inversely related) and plasma glucose (P < 0.001). Apolipoprotein B as well as the ratios total/HDL cholesterol, LDL/HDL cholesterol and Apo B/AI were less effective predictors than LDL cholesterol and did not contribute independently to the estimation of MI risk. Similarly apoprotein AI was a weaker predictor of MI risk then HDL cholesterol. GRIPS is the first prospective cohort study which clearly justifies the key role of LDL cholesterol in preventive strategies. However, the data also give strong support for the additional consideration of other risk factors for a valid estimation of the MI risk for an individual subject.

Improved endothelial function with angiotensin-converting enzyme inhibitors

Associations between coronary events and plasma renin activity, and between coronary risk reduction and angiotensin-converting enzyme (ACE) inhibitors, are now well recognized. Improvement in endothelial function may explain, in part, some of the effects of ACE inhibitors in reducing the rates of adverse cardiovascular outcomes observed in clinical trials. ACE inhibitors have been shown to restore the endothelium-mediated vascular relaxation response in animal models of severe atherosclerosis. Clinical trials are now under way to examine the effect of ACE inhibitors on surrogate outcomes that allow assessment of endothelial function in the progression of carotid and coronary atherosclerosis. The recently completed Trial on Reversing ENdothelial Dysfunction (TREND) demonstrated improved coronary endothelium-dependent vasomotor function after 6 months of treatment with quinapril. In addition, quinapril treatment was associated with a trend toward an increase in microvascular blood flow response. Other studies in progress will assess the effect of ACE inhibitors on clinical coronary risk and plaque progression.

Cell dysfunction in atherosclerosis and the ischemic manifestations of coronary artery disease

Many of the cellular mechanisms and dysfunctions that underlie atherosclerotic plaque formation have been identified, including adverse interactions between atherogenic lipids and the arterial endothelium, loss of endothelium-dependent dilation, accumulation of inflammatory cells and mediators of inflammation in the intima of the arteries, and a decline in anticoagulant defenses. Several studies have shown that these mechanisms, which appear to be active throughout the pathogenesis and progression of atherosclerosis, are reversible within days, weeks, or months with effective lipid-lowering therapy. In addition, the findings of large-scale trials of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors suggest that the rapid improvement observed in trial participants is attributable to a reversal of endothelial and vascular wall dysfunctions rather than to a reduction in plaque size. The accumulated evidence indicates that improved endothelial function can benefit patients who have angina pectoris and/or are at risk for myocardial infarction. Current understanding of the cellular mechanisms of atherogenesis also suggests avenues of future research to refine treatment approaches and further improve outcomes for patients with coronary artery disease.

The potential use of angiotensin-converting enzyme inhibitors in patients with hyperlipidemia

New evidence suggests an interaction between hyperlipidemia, activation of the renin-angiotensin system, and atherosclerotic disease. In patients with atherosclerosis and hyperlipidemia, coronary endothelial dysfunction is usually diffuse and affects vasomotor tone, platelet activity, thrombosis, fibrinolysis, and regulation of inflammatory cells. Angiotensin II, an important oxidant, alters the binding of low-density-lipoprotein (LDL) cholesterol to its receptors and increases endothelial uptake of LDL. Endothelial dysfunction is worsened by the suppression of nitric oxide production and/or release via angiotensin II-associated degradation of bradykinin and oxygen free radical production, resulting in inadequate vasorelaxation. Therapy with angiotensin-converting enzyme (ACE) inhibitors appears to eliminate these untoward effects and may ameliorate the tendency for myocardial infarction associated with elevated plasma levels of angiotensin II. Although the role of ACE inhibitors in the prevention and/or treatment of coronary artery disease in patients without left ventricular dysfunction remains to be established, the capacity of ACE inhibition to correct endothelial dysfunction offers promise. The ability of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors to improve endothelial function, prevent the progression of coronary atherosclerosis, reduce the incidence of ischemic events, and improve survival is well known. Potentially, ACE inhibitors may have an additive or synergistic effect on the development of atherosclerosis and the clinical consequences of this disease when used in combination therapy with lipid-lowering strategies.

Simvastatin, an HMG-coenzyme A reductase inhibitor, improves endothelial function within 1 month

BACKGROUND

Cholesterol-lowering therapy can improve cardiovascular morbidity and mortality in patients with atherosclerosis. Although the mechanisms responsible are unclear, these benefits precede macroscopic changes in the vasculature. Emerging evidence that improvement in endothelial function may occur requires substantiation; in particular, it is unclear how early any such improvement would be detectable after initiation of therapy.

METHODS AND RESULTS

This randomized, double-blind, placebo-controlled crossover study evaluated the effect of simvastatin (20 mg daily for 4 weeks) on endothelium-dependent and endothelium-independent vasodilation and on the response to the inhibitor of nitric oxide synthesis, NG-monomethyl-L-arginine (L-NMMA), in the forearm vasculature of subjects with moderate elevation of total serum cholesterol (6.0 to 10.0 mmol/L) by use of strain-gauge plethysmography. Studies were repeated after 3 more months of open therapy. When the results are expressed as percentage changes in flow in the infused arm relative to the noninfused arm, the vasodilator response to acetylcholine was significantly increased after 4 weeks of treatment with simvastatin (P < .0005), and this improvement was further enhanced after 3 months (P < .005). Concurrently, simvastatin augmented the vasoconstrictor response to L-NMMA, an effect that was maintained at 3 months (P < .0005). The response to the endothelium-independent vasodilator sodium nitroprusside was unaltered.

CONCLUSIONS

These observations indicate that within 1 month of treatment with simvastatin, both the stimulated and basal nitric oxide dilator functions of the endothelium are augmented, and the benefits of this HMG-coenzyme A reductase inhibitor persist with continued therapy.

Coronary vasomotor reactivity among normotensive African and white American subjects with chest pain

BACKGROUND AND OBJECTIVES

Excess cardiovascular morbidity and mortality among African (black) Americans is the subject of intensive investigation but the etiology remains speculative. One hypothesis proposes that inherent, or intrinsic, differences in coronary vascular reactivity and endothelial function predispose African Americans to enhanced vasoconstriction and/or depressed vasodilation, resulting in excess ischemia. The objective of this study was to establish whether coronary vasoreactivity differs among normotensive, nondiabetic African and white Americans with normal arteries referred for coronary arteriography because of chest pain.

PATIENTS AND METHODS

Eleven African American (8 female, 3 male) and 28 white American (9 female, 19 male) normotensive, euglycemic patients with normal coronary arteries were prospectively recruited for invasive testing of coronary artery and microvascular relaxation using the endothelium-dependent and -independent agents, acetylcholine and adenosine; a Doppler tipped intracoronary guidewire; and quantitative coronary angiography.

RESULTS

The study cohort consisted of 17 women (44%) and 22 men (56%) with a mean age of 46 +/- 10 yrs. Of 8 African American women, 6 were premenopausal and 2 were postmenopausal on estrogen replacement therapy. Of 9 white American women, 2 were premenopausal, 1 was 46-year old with a previous history of hysterectomy without ovariectomy, 2 were postmenopausal on estrogen replacement therapy, 2 were perimenopausal and 44- and 54-year old, and 2 were postmenopausal without estrogen replacement therapy. In response to maximal infusion of acetylcholine, epicardial coronary arteries and resistance vessels dilated similarly in black and white subjects. Dose-response curves revealed no significant racial differences during submaximal graded infusion of acetylcholine. In response to peak effect of adenosine, there were no racial differences in dilation of the microcirculation.

CONCLUSIONS

In the absence of hypertension, diabetes mellitus, and angiographic evidence of coronary artery disease, African American women demonstrate no evidence of intrinsic predisposition to enhanced coronary conduit vasoconstriction or depressed microcirculatory dilation in response to the endothelium-dependent and -independent vasodilator agonists-acetylcholine and adenosine-when compared with responses of similar white men and women. Because of low enrollment of black males, definitive conclusions cannot be drawn regarding this group.

Peripheral vasoactivity in familial hypercholesterolemic subjects treated with heparin-induced extracorporeal LDL precipitation (HELP)

Hypercholesterolemia is associated with abnormalities in arterial vasoactivity which can be reversed with cholesterol-reducing therapies. Heparin-induced extracorporeal LDL precipitation (HELP), an invasive method for treating refractory hypercholesterolemia, causes regression of both xanthomas and atherosclerosis, but its effect on vasoactivity has not been investigated. We tested the effects of HELP on vasoactivity with an ultrasound system for continuous measurement of arterial flow velocity and end-diastolic diameter. We measured brachial artery vasoactivity before, during, and after a 5 min forearm vascular occlusion. Vasoactivity measurements were acquired from 6 subjects with familial hypercholesterolemia (FH) who had been treated chronically with HELP, immediately before and after each of 4 treatments, and from 12 age- and sex-matched normocholesterolemic subjects (2 matched with each HELP subject). Peak arterial dilation after cuff release, relative to the pre-occlusion diameter, was similar for the pre-treatment, post-treatment, and normocholesterolemic groups (0.29 mm pre-treatment, 0.30 mm post-treatment and 0.33 mm normocholesterolemic, P = NS). The slope of arterial diameter during occlusion was also similar for the three groups (-0.10 microm/s pre-treatment, 0.02 microm/s post-treatment, and 0.06 microm/s normocholesterolemic, P = NS). These two parameters are known to be decreased in hypercholesterolemic subjects to an extent which could be readily detected by the power of this study. Interestingly, one homozygous FH subject consistently demonstrated significant improvement in these two parameters immediately after HELP, suggesting an individual difference in arterial physiology. On average, FH patients treated chronically with HELP have similar vasoactivity to age- and sex-matched subjects with low risk for atherosclerosis. This result, in light of the many studies that have associated hypercholesterolemia with abnormal vasoactivity, suggests that chronic HELP therapy improves vasoactivity in patients with severe hypercholesterolemia.

LDL apheresis in clinical practice: long-term treatment of severe hyperlipidemia

Thirty patients (13 males, 17 females) suffering from familial hypercholesterolemia resistant to diet and lipid-lowering drugs were treated for 48.7 +/- 19.2 months (range, 2-87 months) with low density lipoprotein (LDL) apheresis. Three different systems (dextran sulfate adsorption for 27 of 30 [Kaneka, Liposorber, Japan], immunoadsorption system for 2 of 30 [Baxter, Therasorb, Germany], immunoadsorption system with special lipoprotein a [Lp(a)] columns for 1 of 30 patients [Lipopak, Pocard, Russia]) were applied. Before LDL apheresis 24 of 30 patients suffered from coronary heart disease (CHD) with angina symptoms. With LDL apheresis, reductions of 46% for total cholesterol, 49% for LDL, 30% for Lp(a), and 38% for triglycerides were reached. Severe side effects such as shock or allergic reactions were very rare (0.5%). In the course of treatment, an improvement in general well-being and increased performance were experienced in 27 of 30 patients. A 60 to 100% reduction of nitrate medication was observed in 17 of 24 patients. Regarding the different apheresis systems used, at the end of the trial there were no significant differences with respect to the clinical outcome experienced by the patients and concerning total cholesterol, LDL, high density lipoprotein, and triglyceride concentrations. But to reduce high Lp(a) levels, the immunoadsorption method with special Lp(a) columns seems to be the most effective (-57% versus 25% [Kaneka] and 23% [Baxter]). The present data clearly 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.

Effect of cholesterol reduction on myocardial ischemia in patients with coronary disease

BACKGROUND

Cholesterol lowering is associated with a reduction in cardiovascular morbidity and mortality. This study sought to determine whether cholesterol lowering also results in a reduction of myocardial ischemia during daily life.

METHODS AND RESULTS

We enrolled 40 patients with proven coronary artery disease, total serum cholesterol between 191 and 327 mg/dL, and at least one episode of ST-segment depression on ambulatory ECG monitoring. Twenty patients were randomized to an American Heart Association Step 1 diet plus placebo (placebo group) and 20 to the same diet plus lovastatin (treatment group). Serum cholesterol and LDL cholesterol levels and ambulatory monitoring were repeated after 4 to 6 months of therapy. The two groups were comparable with respect to baseline characteristics, number of episodes of ST-segment depression, and baseline serum cholesterol levels. The treatment group had lower mean total and LDL cholesterol levels at study end and experienced a significant reduction in the number of episodes of ST-segment depression compared with the placebo group. ST-segment depression was completely resolved in 13 of 20 patients (65%) in the treatment group versus 2 of 20 (10%) in the placebo group. The treatment group exhibited a highly significant reduction in ischemia (P < .001). By logistic regression, treatment with diet and lovastatin was an independent predictor of ischemia resolution.

CONCLUSIONS

Cholesterol lowering with lovastatin appears to be effective in eliminating myocardial ischemia during daily life in a significant proportion of patients.

Atherogenic lipids, vascular dysfunction, and clinical signs of ischemic heart disease

LDL is oxidized in vascular endothelial cells to a highly injurious product that results in characteristic cell dysfunction(s) in large arteries and resistance vessels. The characteristic dysfunctions (ie, loss of dilation, constriction, thrombosis, and inflammation) operate before and throughout the development of atherosclerosis and particularly during plaque rupture. Although oxidized LDL appears to induce these cell/vessel wall dysfunctions in a time- and concentration-dependent manner, Tamai and colleagues have shown that this interaction can be dynamic in that a reduction in lipids restores endothelium-dependent vasomotor function almost immediately. The same intervention (ie, lipid lowering) also appears to stabilize atheroma in the long term, improves endothelium-dependent vasomotion over months, and results in a reduction in clinical signs of risk in coronary heart disease (ie, ischemia and the need for revascularization). The above leads us to some important but unanswered questions. Can we rely on clinical measures of arterial vasomotor dysfunction to represent the other important cell dysfunctions (eg, inflammation, abnormal growth) while monitoring the response to therapeutic interventions? How can we effectively inhibit oxidation of LDL in the arterial wall, and is this useful in reversing the many cell dysfunctions and clinical sequelae of coronary atherosclerosis? What is the time course for restoration of endothelial dysfunction in the atherosclerotic epicardial coronary arteries in patients with effective lipid-lowering therapy? The intracellular responses to oxidized LDL are so numerous (loss of vasodilation, loss of anticoagulant mechanisms, abnormal inflammation, and growth) that targeting therapies to specific pathways may prove difficult. Parallel efforts in basic physiological and clinical research have resulted in remarkable progress that has improved outcomes in patients with coronary heart disease. We expect that many of the characteristic cell/vessel wall dysfunctions that result from adverse interactions with risk factors are dynamic and can be manipulated in a relatively short time frame. Treatment of atherogenic lipids with other risk factors must be further refined and may well become the cornerstone for effective management of angina, unstable syndromes, and ischemia in addition to the control of important outcomes such as myocardial infarction and coronary death.

Antithrombotic treatment in stable coronary syndromes: long-term intermittent urokinase therapy in end-stage coronary artery disease and refractory angina pectoris

Interventions that modify lipid metabolism and blood coagulation have been shown to favourably influence the natural course of coronary artery disease in terms of the primary prevention and treatment of acute cardiovascular events. Various findings suggest that such interventions may also preserve and enhance myocardial perfusion in the chronic stage of the disease. Long-term intermittent urokinase therapy was developed for patients with end-stage coronary artery disease and refractory angina pectoris. A dose of 500,000 IU of urokinase given intravenously as a bolus three times a week for of 12 weeks reduced symptoms by 70% and was accompanied by objective improvements in myocardial perfusion and an increase of ergometric exercise capacity. The possible therapeutic mechanisms of long-term intermittent urokinase therapy-improvement of rheological blood properties mediated by fibrinogen reduction, thrombolysis of non-occlusive subclinical thrombi, and regression of atherosclerotic plaques-are discussed in the context of other antithrombotic approaches.

Influence of radiographic contrast agents on quantitative coronary angiography

PURPOSE

Quantitative angiographic studies on the vasomotility of epicardial coronary arteries are gaining increasing relevance. We investigated whether radiographic contrast agents might influence coronary vasomotor tone and thereby the results of such studies.

METHODS

Coronary angiograms were taken in 12 patients with coronary artery disease at intervals of 5, 3, 2, and 1 min with the low-osmolar, nonionic contrast agent iopamidol 300, and were repeated at identical intervals with the high-osmolar, ionic agent diatrizoate 76%.

RESULTS

Quantitative cine film analysis demonstrated no significant diameter changes in angiographically normal and stenotic coronary arteries with iopamidol. With diatrizoate, however, normal segments were dilated 2% +/- 2% (p < 0.01) after 2 min and 10% +/- 3% after the 1 min interval (p < 0.001). Stenoses showed no uniform responses to diatrizoate.

CONCLUSION

Low-osmolar, nonionic contrast agents should be preferred for quantitative angiographic studies on epicardial coronary vasomotility. When using ionic contrast agents, injection intervals of at least 3 min are required.

Effect of fluvastatin on lipids and fibrinolysis in coronary artery disease

This randomized, double-blind, placebo-controlled study shows that 20-week fluvastatin treatment induces beneficial changes in the lipid panel and a shift in the fibrinolytic pathway toward activation through a decrease in tissue plasminogen activator antigen. Fluvastatin treatment causes no variation in lipoprotein(a) circulating levels.

Prognostic role of cardiovascular risk factors for men with cardiomegaly (the Reykjavik Study)

The Reykjavik Study is a large population-based cohort study, starting in 1967. A total of 9,139 men, born in the years 1907 to 1934, have been followed for 4 to 24 years. Heart size was determined by chest roentgenogram in 2 planes and cardiomegaly, defined as a relative heart size exceeding 550 ml/m2, was detected in 517. Multivariate Cox regression analysis was used to estimate the independent contribution of variables measured at each participant's first visit to the risk of both all-cause and coronary artery disease (CAD) mortality. Cardiomegaly was detected in 3.7% of men aged < 40 years and in 21.2% of those > 75 years. One half of these men had hypertension, one third had manifestations of CAD, and 37% had neither. Among men with cardiomegaly, the presence of CAD had marked deleterious effect on prognosis. Serum total cholesterol and systolic blood pressure were significant independent risk factors of CAD mortality with risk ratio of 1.008 per mg/dl serum cholesterol (95% confidence interval 1.00 to 1.01; p = 0.004) and 1.015/mm Hg (95% confidence interval 1.000 to 1.300; p = 0.043), respectively. Smoking > 25 cigarettes/day carried a 2.3-fold risk (95% confidence interval 1.3 to 4.4; p = 0.008) of all-cause mortality. The traditional risk factors for CAD, serum cholesterol, high blood pressure, and smoking maintain their detrimental effect on prognosis among patients with cardiomegaly. These findings have implications for secondary prevention, signifying that in the presence of cardiomegaly, complacency is not justified in controlling major risk factors for CAD.

Renal hemodynamic effects of lovastatin in a renal ablation model

OBJECTIVES

Patients with renal mass reduction of more than 50% are at increased risk for progressive renal failure. Lipid-lowering agents have been shown to preserve renal function in various models of chronic renal failure. This study was performed to evaluate the hemodynamic effects of lovastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, in the remnant kidney model.

METHODS

Two groups of animals were studied. Group 1 (n = 9) served as controls and group 2 (n = 14) received lovastatin, 15 mg/kg/day orally, for 2 weeks after renal ablation. Glomerular filtration rate (GFR, inulin clearance), renal blood flow (RBF, ultrasonic flow probe), and 24-hour protein excretion were measured in anesthetized rats.

RESULTS

Two weeks after renal ablation, GFR was 0.28 +/- 0.09 mL/min/gkw (gram kidney weight) in group 1, whereas in group 2, lovastatin preserved GFR at 0.58 +/- 0.3 mL/min/gkw (P < 0.05). RBF in group 1 was 1.2 +/- 0.2 mL/min/gkw and increased to 2.1 +/- 0.4 mL/min/gkw in group 2 (P < 0.05), representing a 43% increase. Protein excretion decreased significantly to 13 +/- 1.7 mg/24 hr in group 2. The lovastatin-treated group had a lower serum cholesterol (59 +/- 3 mg/dL versus 71 +/- 2 mg/dL, P < 0.05), but serum triglyceride levels were not different between the two groups.

CONCLUSIONS

Lovastatin preserves renal function in a renal ablation model after 2 weeks of treatment. It specifically increased total RBF. Therefore, in addition to its known cholesterol lowering effect, lovastatin also has the direct renal hemodynamic effect of increasing RBF and maintaining GFR.

The Lipoprotein and Coronary Atherosclerosis Study (LCAS): design, methods, and baseline data of a trial of fluvastatin in patients without severe hypercholesterolemia

Few direct clinical data are available regarding whether cholesterol-lowering therapy should be extended to patients with coronary heart disease (CHD) and normal or only slightly elevated plasma cholesterol concentrations. The one published angiographic trial designed to examine this question found no benefit. Additional prospective data will be provided by the Lipoprotein and Coronary Atherosclerosis Study (LCAS), a randomized, double-blind, placebo-controlled trial of fluvastatin therapy (20 mg twice daily) monitored by both quantitative coronary angiography (QCA) and, in a subset of patients, positron-emission tomography (PET). Eligible subjects in LCAS were men and women 35-75 years of age with low-density lipoprotein (LDL) cholesterol of 115-190 mg/dL on stable dietary therapy and with angiographic evidence by caliper measurement of at least one coronary atherosclerotic lesion causing 30-75% diameter stenosis. Among the 429 patients randomized (mean age 58.8, 81% male), mean baseline LDL cholesterol was only 145.6 mg/dL. Any patient with mean prerandomization LDL cholesterol of 160 mg/dL or higher also received open-label adjunctive cholestyramine. The primary endpoint is within-patient per-lesion change in minimum lumen diameter (MLD) as measured by QCA at baseline and 2.5-year follow-up. All evaluable lesions had MLD at least 0.8mm less than the reference lumen diameter at either baseline or follow-up and MLD at least 25% of the reference lumen diameter at baseline. Data obtained on myocardial perfusion changes (99 patients underwent initial PET), special lipid particles, and coagulation factors may help define which patients with CHD and relatively low LDL cholesterol will benefit from lipid-lowering treatment.

Low density lipoprotein apheresis improves regional myocardial perfusion in patients with hypercholesterolemia and extensive coronary artery disease. LDL-Apheresis Atherosclerosis Regression Study (LAARS)

OBJECTIVES

In a randomized study we evaluated the effect of biweekly low density lipoprotein (LDL) apheresis plus simvastatin versus medication alone on regional myocardial perfusion.

BACKGROUND

In patients with severe hypercholesterolemia, diet and lipid-lowering drugs are often insufficient to achieve optimal LDL cholesterol values. Low density lipoprotein apheresis is a very effective lipid-lowering therapy. Assessment of regional myocardial perfusion enables evaluation of the functional state of the coronary circulation.

METHODS

We studied 42 patients with severe hypercholesterolemia and extensive coronary artery disease who were randomized to diet and simvastatin with or without biweekly LDL apheresis. Regional myocardial perfusion was assessed by digital subtraction angiography with videodensitometric calculation of hyperemic mean transit time (HMTT) of contrast medium at baseline and after 2 years of therapy.

RESULTS

Low density lipoprotein cholesterol decreased by 63% (to 3.0 mmol/liter) in the LDL apheresis group and by 47% (to 4.1 mmol/liter) in the medication group. Paired HMTT measurements were assessed in 43 regions in the LDL apheresis group and 35 regions in the medication group. In the LDL apheresis group, regional HMTT decreased over 2 years from 3.35 +/- 1.18 (mean +/- SD) to 2.87 +/- 0.82 s (-14%, p = 0.001), whereas no change in the medication group was observed: 2.95 +/- 1.06 to 2.96 +/- 0.90 s (p = NS). In the patient-based comparison, the mean change in HMTT was -0.45 s (-14%, p = 0.01) in the LDL apheresis group and -0.05 s (-2%, p = NS) in the medication group, respectively. Only exercise-induced ischemia improved in the LDL apheresis group.

CONCLUSIONS

Biweekly LDL apheresis plus simvastatin decreased time-averaged LDL cholesterol levels by an additional 31% (1.1 mmol/liter) compared with medication alone. After 2 years of therapy, regional myocardial perfusion improved in the LDL apheresis group and remained unchanged in the medication group. Thus, aggressive reduction of LDL cholesterol has a favorable effect on regional myocardial perfusion and alleviates ischemia.

Coronary flow reserve is impaired in young men with familial hypercholesterolemia

OBJECTIVES

We sought to investigate whether functional abnormalities in coronary vasomotion exist in young adults by studying 15 men (age 31 +/- 8 years [mean +/- SD]) with familial hypercholesterolemia (FH) and a matched group of 20 healthy control subjects.

BACKGROUND

Precursors of morphologic coronary artery disease are known to be present in adolescents and young adults with a high risk factor profile.

METHODS

Myocardial blood flow was measured at the basal state and during dipyridamole-induced hyperemia using positron emission tomography and oxygen-15-labeled water.

RESULTS

Serum total and low density lipoprotein cholesterol concentrations were higher in the patients than in the control subjects (mean +/- SD): 7.7 +/- 1.9 versus 5.3 +/- 1.5 mmol/liter (298 +/- 73 vs. 205 +/- 58 mg/dl) and 6.1 +/- 1.8 versus 3.5 +/- 1.4 mmol/liter (236 +/- 70 vs. 135 +/- 54 mg/dl), respectively (both p < 0.001). The baseline myocardial blood flow was similar in the patients and control subjects: 0.92 +/- 0.24 versus 0.83 +/- 0.13 ml/g per min, respectively (p = 0.21). A significant increase in flow was observed in both groups after dipyridamole infusion, but the flow at maximal vasodilation was 29% lower in the patients: 3.19 +/- 1.59 versus 4.49 +/- 1.27 ml/g per min (p = 0.011). Consequently, coronary flow reserve (the ratio of hyperemia flow to basal flow) was 35% lower in the patients than in the control subjects: 3.5 +/- 1.6 versus 5.4 +/- 1.5 (p = 0.0008). Total coronary resistance during hyperemia was higher in the patients than in the control subjects: 36 +/- 25 versus 21 +/- 10 mm Hg/min per g per ml (p = 0.045). Coronary flow reserve was inversely associated with serum total cholesterol concentration: r = -0.43 (p = 0.009).

CONCLUSIONS

Coronary flow reserve is reduced in young men with FH, and, consequently, coronary resistance during hyperemia is increased. The results demonstrate very early impairment of coronary vasomotion in hypercholesterolemic patients.

Endothelial nitric oxide pathway function in the peripheral vasculature of patients with heart failure

Many studies have investigated the pathophysiologic contributions of abnormalities in the endothelial nitric oxide pathway to the heightened vasoconstrictor tone that is characteristic of the clinical syndrome of heart failure. The most consistent abnormality is a reduced vasodilator response to muscarinic stimulation with either acetylcholine or methacholine, a finding which has been identified in several animal models of heart failure as well as in forearm and leg resistance vessels in patients with heart failure. More recent studies with desmopressin, a vasopressin 2 receptor agonist that stimulates nitric oxide production independent of the muscarinic receptor, have demonstrated that the abnormality in endothelium-dependent vasodilation was not limited to the muscarinic pathway. At present, the mechanisms of the defect in the endothelial nitric oxide pathway are unknown. But, they appear not to be directly related to sympathetic stimulation. Finally, studies using transplant recipients have demonstrated that this defect is reversible. In addition, a pilot study has demonstrated that supplemental oral L-arginine, the precursor for nitric oxide, has beneficial effects on forearm blood flow responses to exercise, arterial compliance nad functional status as assessed by increased distances during a 6-minute walk test and lower scores on the Living with Heart Failure Questionnaire. These studies suggest that the endothelial nitric oxide pathway may be a target for therapeutic interventions in heart failure.

Prevention and regression of atherosclerosis: effects of HMG-CoA reductase inhibitors

OBJECTIVE

To review the current literature on the effects of hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors in secondary prevention and regression of atherosclerosis.

DATA SOURCES

A MEDLINE and journal search of recent studies evaluating the effects of lipid lowering with HMG-CoA reductase inhibitors on serum cholesterol as well as progression and regression of atherosclerotic coronary or carotid disease in patients with established atherosclerotic disease was conducted. Articles addressing the pathophysiology of atherosclerotic disease were identified by using the same sources.

STUDY SELECTION

All available studies evaluating the use of HMG-CoA reductase inhibitors in the progression and regression of coronary and carotid atherosclerosis were reviewed.

DATA SYNTHESIS

Lowering of total serum cholesterol, low-density lipoprotein cholesterol, and triglycerides, as well as increasing high-density lipoprotein cholesterol can be achieved with HMG-CoA reductase inhibitors. Aggressive lipid lowering has been demonstrated to alter progression of established atherosclerotic disease and, in some patients, actually induce regression of the atheroma. An unexpected finding of several trials was the early and significant reduction in clinical cardiac events. Other mechanisms by which clinical event reduction may be explained include plaque stabilization and restoration of endothelium vasodilation.

CONCLUSIONS

Aggressive lipid-lowering therapy using HMG-CoA reductase inhibitors appears to alter the natural progression and promote regression of atherosclerosis in selected patients with established coronary or carotid atherosclerosis. However, it is unlikely that regression of atherosclerosis alone is responsible for the marked reduction in clinical cardiac events seen in these trials.

Atherosclerosis and restenosis: reflections on the Lovastatin Restenosis Trial and Scandinavian Simvastatin Survival Study

Atherosclerosis is related to serum lipids, whereas restenosis after coronary angioplasty is probably not, reflecting different pathophysiologies. Nonetheless, treatment of lipid disorders is appropriate after angioplasty.