Prevention of progression of coronary atherosclerosis by treatment of hyperlipidaemia: a seven year prospective angiographic study

Distinct kinetic and spatial patterns of protein kinase C (PKC)- and epidermal growth factor receptor (EGFR)-dependent activation of extracellular signal-regulated kinases 1 and 2 by human nicotinic acid receptor GPR109A

Nicotinic acid (niacin) has been widely used as a lipid-lowering drug for several decades, and recently, orphan G protein-coupled receptor GPR109A has been identified as a receptor for niacin. Mechanistic investigations have shown that, upon niacin activation, GPR109A couples to a G(i) protein and inhibits adenylate cyclase activity, leading to inhibition of liberation of free fatty acid. However, the underlying molecular mechanisms for GPR109A signaling remain largely unknown. Using CHO-K1 cells stably expressing GPR109A and A431 cells, which are a human epidermoid cell line with high levels of endogenous expression of functional GPR109A receptors, we found that activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) by niacin was rapid, peaking at 5 min, and was significantly blocked by pertussis toxin. Furthermore, time course experiments with different kinase inhibitors demonstrated that GPR109A induced ERK1/2 activation via the matrix metalloproteinase/epidermal growth factor receptor transactivation pathway at both early and later time points (2-5 min); this pathway was distinct from the PKC pathway-mediated ERK1/2 phosphorylation that occurs at early time points (≤2 min) in response to niacin. Overexpression of Gβγ subunit scavengers βARK1-CT and the Gα subunit of transducin led to a significant reduction of ERK1/2 phosphorylation, suggesting a critical role for βγ subunits in GPR109A-activated ERK1/2 phosphorylation. Using arrestin-2/3-specific siRNA and an internalization-deficient GPR109A mutant, we found that arrestin-2 and arrestin-3 were not involved in GPR109A-mediated ERK1/2 activation. In conclusion, our findings demonstrate that upon binding to niacin GPR109A receptors initially activate G(i), leading to dissociation of the Gβγ subunit from activated G(i), and subsequently induce ERK1/2 activation via two distinct pathways, one PKC-dependent pathway occurring at a peak time of ≤2 min and the other matrix metalloproteinase-dependent growth factor receptor transactivation occurring at both early and later time points (2-5 min).

Discovery of a biaryl cyclohexene carboxylic acid (MK-6892): a potent and selective high affinity niacin receptor full agonist with reduced flushing profiles in animals as a preclinical candidate

Biaryl cyclohexene carboxylic acids were discovered as full and potent niacin receptor (GPR109A) agonists. Compound 1e (MK-6892) displayed excellent receptor activity, good PK across species, remarkably clean off-target profiles, good ancillary pharmacology, and superior therapeutic window over niacin regarding the FFA reduction versus vasodilation in rats and dogs.

Discovery of pyrazolyl propionyl cyclohexenamide derivatives as full agonists for the high affinity niacin receptor GPR109A

A series of pyrazolyl propionyl cyclohexenamides were discovered as full agonists for the high affinity niacin receptor GPR109A. The structure-activity relationship (SAR) studies were aimed to improve activity on GPR109A, reduce Cytochrome P450 2C8 (CYP2C8) and Cytochrome P450 2C9 (CYP2C9) inhibition, reduce serum shift and improve pharmacokinetic (PK) profiles.

Acyl hydroxypyrazoles as novel agonists for high-affinity nicotinic acid receptor GPR109A: WO2008051403

BACKGROUND

Acyl hydroxypyrazoles were discovered and claimed by Merck as novel agonists for the high-affinity nicotinic acid receptor, G-protein coupled receptor 109A (GPR109A). The fused bicyclic core contains a hydroxypyrazole that mimics the anthranilide moiety described in their earlier patents and patent publications.

OBJECTIVE

This article evaluates new GPR109A receptor agonists disclosed by Merck in the recent patent WO2008051403.

CONCLUSION

The aim of this invention was to provide potential therapy to reduce free fatty acids (FFA), low-density lipoprotein cholesterol (LDL-C), total cholesterol, and serum triglycerides (TG), and to raise high-density lipoprotein cholesterol (HDL-C). Thus, these agonists could - potentially - be used to treat dyslipidemia, atherosclerosis, and metabolic syndromes such as diabetes.

Novel patent publications on high-affinity nicotinic acid receptor agonists

BACKGROUND

Nicotinic acid (NA) has been used as a drug to treat dyslipidemia for > 50 years. In outcome clinical trials, NA displayed remarkable efficacy in patients with cardiovascular diseases by modifying lipid profiles that results in reduced morbidity and mortality. On the other hand, NA induces vasodilation (flushing) that undermines treatment compliance. In addition, high-dose treatment is required presumably owing to the poor pharmacokinetic properties of NA. The identification of the high-affinity NA receptor, namely G-protein coupled receptor 109A (GPR109A), led to further understanding of the pharmacological effects of NA and discovery of compounds that are potentially superior in efficacy yet devoid of NA's adverse effects.

OBJECTIVE/METHOD

This review focuses on the endeavors of several pharmaceutical companies to discover and develop GPR109A agonists. Representative compounds of each series in patent literature since 2005 are highlighted.

CONCLUSION

Highly potent GPR109A agonists with minimal flushing effects and robust free fatty acid reduction have been identified. Despite the failure of the partial agonist MK-0354 to achieve efficacy in a Phase II clinical trial, at least three other GPR109A agonists have been evaluated in clinical trials. The upcoming clinical data would be critical to validate the therapeutic utility of this receptor.

Discovery of novel tricyclic full agonists for the G-protein-coupled niacin receptor 109A with minimized flushing in rats

Tricyclic analogues were rationally designed as the high affinity niacin receptor G-protein-coupled receptor 109A (GPR109A) agonists by overlapping three lead structures. Various tricyclic anthranilide and cycloalkene carboxylic acid full agonists were discovered with excellent in vitro activity. Compound 2g displayed a good therapeutic index regarding free fatty acids (FFA) reduction and vasodilation effects in rats, with very weak cytochrome P450 2C8 (CYP2C8) and cytochrome P450 2C9 (CYP2C9) inhibition, and a good mouse pharmacokinetics (PK) profile.

Reduction of mortality in the Stockholm Ischaemic Heart Disease Secondary Prevention Study by combined treatment with clofibrate and nicotinic acid

Consecutive survivors of a myocardial infarction from the Southern Hospital, below 70 years of age, were randomized into a Control group (n = 276) and a Treatment group (n = 279). The latter was openly prescribed the combination of clofibrate and nicotinic acid for serum lipid lowering. Each patient should remain in the study for 5 years and be seen regularly every 4 months at a special IHD outpatient clinic within the hospital. The concentration of serum cholesterol and triglyceride was lowered by 13% and 19%, respectively, in the Treatment group compared to the Control group. Total mortality was 82 cases in the Control group and 61 in the Treatment group, a 26% reduction (p less than 0.05). For patients above 60 years of age in the Treatment group the reduction in mortality was 28% (p less than 0.05). IHD mortality was reduced by 36% (p less than 0.01) in the Treatment group compared to the Control group. The beneficial effect of the serum lipid lowering treatment was related to the serum triglyceride concentration in two ways. First, it only occurred in patients with a triglyceride level greater than 1.5 mmol/l (n = 216). Secondly, it was most pronounced in the 44% of the treated patients who had a lowering of the serum triglyceride by 30% or more, and in this subgroup the reduction of IHD mortality was 60% (p less than 0.01). For serum cholesterol there were no such relations. The difference between serum triglycerides and cholesterol concerning these relations to the treatment outcome may be due to the fact that hypertriglyceridaemia was the most common hyperlipidaemia among our patients, occurring in 50%, while hypercholesterolaemia only occurred in 13%. Caution should be exercised in the interpretation of the results as the trial was not blind. However, the fact that the decrease in IHD deaths was directly related to the degree of serum triglyceride lowering indicates that it was the drug effect on serum lipids that was responsible for the beneficial effect of the treatment.

Discovery of pyrazolopyrimidines as the first class of allosteric agonists for the high affinity nicotinic acid receptor GPR109A

Pyrazolopyrimidines were discovered as the first class of allosteric agonists for the high affinity nicotinic acid receptor GPR109A. In addition to its intrinsic activity, compound 9n significantly enhances nicotinic acid binding to the receptor, thereby potentiating the functional efficacy of nicotinic acid.

Tetrahydro anthranilic acid as a surrogate for anthranilic acid: application to the discovery of potent niacin receptor agonists

The design, synthesis, and biological activity of a series of cycloalkene acid-based niacin receptor agonists are described. This led to the discovery that tetrahydro anthranilic acid is an excellent surrogate for anthranilic acid. Several compounds were identified that were potent against the niacin receptor, had enhanced cytochrome P450 selectivity against subtypes CYP2C8 and CYP2C9, and improved oral exposure in mice.

Discovery of biaryl anthranilides as full agonists for the high affinity niacin receptor

Biaryl anthranilides are reported as potent and selective full agonists for the high affinity niacin receptor GPR109A. The SAR presented outlines approaches to reduce serum shift and both CYPCYP2C8 and CYP2C9 liabilities, while improving PK and maintaining excellent receptor activity. Compound 2i exhibited good in vivo antilipolytic efficacy while providing a significantly improved therapeutic index over vasodilation (flushing) with respect to niacin in the mouse model.

Discovery of orally bioavailable and novel urea agonists of the high affinity niacin receptor GPR109A

A urea class of high affinity niacin receptor agonists was discovered. Compound 1a displayed good PK, better in vivo efficacy in reducing FFA in mouse than niacin, and no vasodilation in a mouse model. Compound 1q demonstrated equal affinity to GPR109A as niacin.

Triglyceride modulation by acifran analogs: activity towards the niacin high and low affinity G protein-coupled receptors HM74A and HM74

Niacin is known to exert profound beneficial effects on cholesterol levels in humans, although its use is somewhat hampered by the gram quantities necessary to exert effects and the prevalence of compliance-limiting skin flushing side effects that occur. Recently, two G protein-coupled receptors (GPCRs) for niacin were identified and characterized as high (HM74A; GPR109A) and low (HM74; GPR109B) affinity receptors based on the binding affinities of niacin. These receptors also bind acifran (AY-25,712), which is known to modulate lipid levels like niacin, with similar affinities. Twelve analogs of acifran were chemically synthesized. One analogue demonstrated a dose-dependent decrease in serum triglycerides in rats within 3h of oral administration. Next, the acifran analogs were assessed for their activity towards the high and low affinity niacin receptors expressed in CHO-K1 cells. Constructs expressing HM74A or HM74 were stably transfected into CHO-K1 cells and shown to elicit phosphorylation of p42 and p44 mitogen-activated protein kinase (ERK1/ERK2) phosphorylation upon addition of niacin or acifran. The presence of functionally coupled GPCRs was further confirmed using Pertussis toxin, which completely inhibited the ability of either niacin or acifran to elicit phospho-ERK1/ERK2. The EC(50) of p-ERK1/ERK2 for niacin for the high and low affinity receptors was 47nM and indeterminate (i.e., >100microM), respectively, while the EC(50) for acifran was 160 and 316nM, respectively. Two chemical analogs of acifran demonstrated robust phosphorylation of ERK1/ERK2. Collectively, these data suggest that the synthesis of acifran analogs may be a suitable path for developing improved HM74A agonists.

Effect of nicotinic acid administration on hepatic very low density lipoprotein-triglyceride production

Our objective was to examine very low density lipoprotein-triglyceride (VLDL-TG) kinetics after chronic and acute administration of nicotinic acid (NA). Incorporation of [1,2,3,4-(13)C(4)]palmitate and [2-(13)C(1)]glycerol into VLDL-TG was measured in five healthy, normolipidemic women. Each subject was studied twice; the 4-day hospital stays were separated by 1 mo, during which time doses of NA were increased to 2 g/day (500 mg, 4 times/day). During posttreatment study, 500 mg of NA were administered acutely at 0800. Under baseline postabsorptive conditions, incorporation curves from (13)C-labeled free fatty acid (FFA) and (13)C-labeled glycerol were superimposable, and VLDL-TG kinetics were in agreement (t(1/2) = 1.4 +/- 0.3 and 1.3 +/- 0.3 h, and production rates = 27.2 +/- 6.1 and 28.5 +/- 5.3 g/day, respectively). In the postabsorptive state after chronic NA therapy, VLDL-TG concentrations and production rates were lower despite a trend toward elevated plasma FFA concentrations and fluxes. After the acute dose of NA, plasma FFA concentrations and flux fell dramatically, and there was a virtual halt to VLDL-TG production, which continued throughout the 6-h period after NA, despite a marked rebound overshoot in serum FFA concentrations and flux after hour 2. Plasma homocysteine concentrations increased 68% (P < 0.001) in the NA phase, consistent with chronic increased transmethylation demand. We conclude that 1) NA acutely and chronically decreases VLDL-TG production rate in normal women; 2) the acute effect on VLDL-TG production is associated with an initial suppression of lipolysis but persists for several hours after the antilipolytic action of NA has abated and is observed in the basal postabsorptive state, when lipolytic rates are not reduced; and 3) the effect of NA on VLDL-TG production, therefore, cannot be completely explained by its antilipolytic actions.

Treatment of hyperlipidemia by specialists versus generalists as secondary prevention of coronary artery disease

Patients with known coronary disease and low-density lipoprotein >130 mg/dl who are followed by cardiologists after myocardial infarction are more than twice as likely to receive a cholesterol-lowering agent than patients followed by general internists.

The secondary prevention of coronary artery disease

Randomized clinical trials demonstrate the efficacy of medical secondary prevention in coronary disease patients. The magnitude of risk reduction with exercise, diet, lipid modification, and smoking cessation is similar to other medical therapies for coronary disease such as aspirin, beta blockers, as well as coronary bypass surgery, (Table VI) In contrast to these therapies, however, secondary prevention stabilizes angiographic progression in about 50% of patients and induces regression in about 25% of patients. Both symptoms and perceived quality of life also are beneficially altered by secondary prevention programs, although possibly not by the magnitude reported for bypass surgery. These clinical trial results have led the American Heart Association, and the American College of Cardiology to strongly endorse secondary prevention. A reasonable projection based on these clinical trial data is that widespread use of these recommendations in the 12 million established coronary disease patients would significantly reduce coronary mortality and morbidity.

Long-term Treatment With Pravastatin Alone and in Combination With Gemfibrozil in Familial Type IIB Hyperlipoproteinemia or Combined Hyperlipidemia

BACKGROUND: Pravastatin inhibits 3-hydroxy-3-methylglutaryl-coenzyme A reductase. It prevents mevalonate synthesis, reducing endogenous cholesterol production, and reduces cholesterol content in the liver, thus resulting in a down-regulation of low-density lipoprotein receptor production. Gemfibrozil reduces very low-density lipoprotein production and low-density lipoprotein-cholesterol level and increases very low-density lipoprotein catabolism. Therefore, it was suggested that combination therapy with both drugs could effect greater reduction of cholesterol levels as compared to pravastatin alone. The present study was carried out to evaluate the efficacy and safety of pravastatin as a monotherapy or in combination with gemfibrozil in the treatment of patients with familial type IIb hyperlipoproteinemia or familial combined hyperlipidemia. METHODS AND RESULTS: Forty-one patients were included in the study. All patients initially followed 6 weeks of hypolipidemic diet; subsequently they were randomized and received either 20 mg once daily of pravastatin alone (n = 13) or 20 mg of pravastatin together with 600 mg of gemfibrozil twice daily (n = 14). As a control, 14 patients were treated with diet only. The treatment lasted 24 months and clinical evaluation and laboratory tests were done at given time points. Both groups of treated patients showed an early reduction (3 months) of total (about 30% P <.01 vs controls), low-density lipoprotein (about 35%, P <.01 vs controls) and very low-density lipoprotein cholesterol levels (about 18%, P = NS). In contrast, high-density lipoprotein cholesterol levels increased significantly in patients treated with pravastatin and gemfibrozil (about 20%, P <.05 vs controls). Pravastatin treatment alone reduced the level of serum triglycerides as efficiently as in combination with gemfibrozil. Data showed a sustained normalization of lipid profile until 24 months. However, this effect was achieved in patients that had rather low levels of triglycerides. During the treatment we did not observe any difference in the incidence of possible drug-related side effects. Severe myopathy or rhabdomyolysis was not observed at the doses of the drugs used in our study. CONCLUSIONS: Therapy with pravastatin and in combination with gemfibrozil resulted in significant and sustained normalization of lipid profile in high-risk patients with familial type IIb hyperlipoproteinemia or familial combined hyperlipidemia.

Assessing the independent effect of dietary counseling and hypolipidemic medications on serum lipids

Determination of changes in total cholesterol (TC) and triglyceride (TG) levels has focused primarily on hypolipidemic drug effects. Changes resulting from dietary effect alone versus diet and drug effect have not yet been fully established. Seventy subjects were enrolled into four treatment groups to determine the impact of diet and drug effect upon TC and TG. Group 1 (n = 28) served as the control group and received no dietary counseling or drug therapy. Group 2 (n = 22) received dietary counseling. Group 3 (n = 7) underwent dietary counseling for six months and drug therapy for eighteen months. Subjects in groups 1-3 were monitored for eighteen months. Patients in group 4 (n = 13) were followed up for thirty-six months. No intervention occurred during the first eighteen months, and hypolipidemic medications were used during the second eighteen-month period. Subjects in groups 1 and 4 received no specific dietary counseling and demonstrated no significant improvement over the course of the study. Patients in groups 2 and 3 showed significant reductions in both TC and TG. The improvement in TC seen for patients in group 3 was reduced after dietary counseling ceased. Dietary intervention is necessary if patients are to statistically significantly reduce TC and TG levels. Drug therapy demonstrated the expected reductions in both TC and TG but did not statistically significantly lower lipid levels without concomitant dietary counseling. When dietary counseling and hypolipidemic medications are used together, reductions in TC and TG values are even greater than those seen with dietary effect alone. Diet control alone appears to significantly reduce TC and TG levels, resulting in reduced need for antianginal medications.

Age-related changes affecting atherosclerotic risk. Potential for pharmacological intervention

The incidence of cardiovascular diseases that are related to the atherosclerotic process increases exponentially with age. Organ lesions, the clinical manifestation of atherosclerotic disease, are late events due to complications in the plaque (ulceration, thrombosis, calcification) which are the result of an increased vulnerability to disruption of a previously stable plaque. The higher incidence of age-related clinical events could be explained by a rising sensitivity of plaques to destabilising factors, both parietal and humoral. The increased probability that a plaque in an elderly patient will became vulnerable could be related to those destabilising factors that significantly increase with aging, such as advanced glycation end-products. For these reasons, it seems most important that the analysis of these age-related destabilising factors, rather than those factors that promote the development of early atherosclerotic plaques, should be undertaken. Taking the point of view of a pharmacological intervention, this should eventually lead to a more complete understanding of this process.

Treating hyperlipidemia in the elderly

BACKGROUND

Determination of the effects of dietary modification and hyperlipidemic medications in the elderly (> sixty-five years of age) patient has not been significantly investigated to date despite knowledge that elevated cholesterol (TC) and triglyceride (TG) levels increase the risk of coronary artery disease (CAD).

METHODS

Twenty-seven individuals were placed into one of three treatment groups and longitudinally followed up to examine the effects of diet and hyperlipidemic medications on TC and TG levels. Group 1 (n = 14) received neither dietary nor drug therapy. Group 2 (n = 9) received dietary counseling without concomitant hyperlipidemic medications. Subjects in group 3 (n = 4) underwent dietary instruction for six months and hyperlipidemic medication(s) for eighteen months.

RESULTS

Subjects in group 1 demonstrated a statistical increase in TC (P < or = 0.001) during the study. Patients in groups 2 (P < or = 0.001) and 3 (P < or = 0.05) demonstrated statistical improvement in TC reduction during dietary counseling. The effect on TC was blunted in group 3 after dietary counseling was discontinued. Reductions in TG levels were significant (P < or = 0.001) only for patients in group 2.

CONCLUSION

Elderly individuals were able to significantly reduce both TC and TG levels by dietary modification alone. Minimal improvement was seen with the addition of hyperlipidemic medications.

High-density lipoprotein cholesterol level and smoking modify the prognosis of patients with coronary vasospasm

A cardiovascular event analysis was performed in a subset of 80 consecutive patients with vasospastic coronary artery disease. During the follow-up period (30 +/- 2 months, mean +/- SD), 9 patients had vascular accidents, including acute myocardial infarction, unstable angina, and stroke (Group A), while the remaining 71 patients were eventfree (Group B). Serum total-cholesterol, low-density lipoprotein cholesterol, and triglyceride levels were not different between the two groups at the baseline as well as after follow-up. However, the HDL-C level at baseline was significantly lower in Group A (33.5 +/- 2.6 mg/dl) than in Group B (41.9 +/- 1.7 mg/dl, p < 0.05). The HDL-C level increased significantly during the follow-up in Group B (delta HDL-C: 6.2 +/- 1.2 mg/dl, p < 0.01), but not in Group A (delta HDL-C: -3.2 +/- 2.7 mg/dl). The HDL-C level after follow-up was significantly lower in Group A (30.3 +/- 2.9 mg/dl) than in Group B (48.1 +/- 1.5 mg/dl, p < 0.01). Current smokers at the end of the follow-up period were more prevalent in Group A (67%) than in Group B (11%, p < 0.01). Cardiovascular accidents occurred more often in current smokers (6/14, 43%) at the end of the follow-up than in current nonsmokers, including quitters (3/66, 5%; p < 0.05). The HDL-C level was increased significantly (delta HDL: 6.2 +/- 1.3 mg/dl, p < 0.01) in the latter patients, but not in the former (delta HDL: -0.4 +/- 2.9 mg/dl).(ABSTRACT TRUNCATED AT 250 WORDS)

Lipid lowering and plaque regression. New insights into prevention of plaque disruption and clinical events in coronary disease

The consensus of evidence from angiographic trials demonstrates both coronary artery and clinical benefits from lowering of lipids by a variety of regimens. The findings of reduced arterial disease progression and increased regression have been convincing but, at best, modest in their magnitude. For example, among those treated intensively in FATS, the mean improvement in proximal stenosis severity per patient was < 1% stenosis, and only 12% of all lesions showed convincing regression. In view of these modest arterial benefits, the associated reductions in cardiovascular events have been surprisingly great. For example, coronary events were reduced 75% in FATS; this was entirely a result of a 93% reduction in the likelihood that a mildly or moderately diseased arterial segment would experience substantial progression to a severe lesion at the time of a clinical event. We believe that the magnitude of the clinical benefit is best explained in terms of this observation, according to the following lines of reasoning. Clinical events most commonly spring from lesions that are initially of mild or moderate severity and then abruptly undergo a disruptive transformation to a severe culprit lesion. The process of plaque fissuring, leading to plaque disruption and thrombosis, triggers most clinical coronary events. Fissuring is predicted by a large accumulation of core lipid in the plaque and by a high density of lipid-laden macrophages in its thinned fibrous cap. Lesions with these characteristics constitute only 10-20% of the overall lesion population but account for 80-90% of the acute clinical events. In the experimental setting, normalization of an atherogenic lipid profile substantially decreases the number of lipid-laden intimal macrophages (foam cells) and depletes cholesterol from the core lipid pool. In the clinical setting, intensive lipid lowering virtually halts the progression of mild and moderate lesions to clinical events. Thus, the reduction in clinical events observed in these trials appears to be best explained by the relation of the lipid and foam cell content of the plaque to its likelihood of fissuring and by the effects of lipid-lowering therapy on these "high-risk" features of plaque morphology. The composite of data presented here supports the hypothesis that lipid-lowering therapy selectively depletes (regresses) that relatively small but dangerous subgroup of fatty lesions containing a large lipid core and dense clusters of intimal macrophages. By doing so, these lesions are effectively stabilized and clinical event rate is accordingly decreased.

Efficacy of gemfibrozil in dyslipidaemic subjects with suspected heart disease. An ancillary study in the Helsinki Heart Study frame population

During screening in the Helsinki Heart Study (HHS), a 5-year coronary primary prevention trial with gemfibrozil, some 600 dyslipidaemic individuals were detected who exhibited symptoms and signs of possible coronary heart disease (CHD). These subjects were excluded from the primary study. To secure successful conduct in the HSS, an ancillary protocol was developed for the treatment of these individuals. Three-hundred and eleven subjects were randomized to receive gemfibrozil 600 mg twice daily and 317 subjects to receive a matching placebo over 5 years in a double-blind fashion. The end-point rate, consisting of fatal and non-fatal myocardial infarction and cardiac death, did not differ significantly between the placebo and gemfibrozil groups. The same was true for total mortality. Missing key prognostic factors, e.g. true prevalence of CHD, extent of coronary artery obstructions, degree of left ventricular dysfunction, and their distribution in the groups render the results less reliable and hence the data cannot be used to refute the thesis that treatment of dyslipidaemia in manifest CHD in successful.

Regular physical exercise and low-fat diet. Effects on progression of coronary artery disease

BACKGROUND

Significant regression of coronary and femoral atherosclerotic lesions has been documented by angiographic studies using aggressive lipid-lowering treatment. This study tested the applicability and effects of intensive physical exercise and low-fat diet on coronary morphology and myocardial perfusion in nonselected patients with stable angina pectoris.

METHODS AND RESULTS

Patients were recruited after routine coronary angiography for stable angina pectoris; they were randomized to an intervention group (n = 56) and a control group on "usual care" (n = 57). Treatment comprised intensive physical exercise in group training sessions (minimum, 2 hr/wk), daily home exercise periods (20 min/d), and low-fat, low-cholesterol diet (American Heart Association recommendation, phase 3). No lipid-lowering agents were prescribed. After 12 months of participation, repeat coronary angiography was performed; relative and minimal diameter reductions of coronary lesions were measured by digital image processing. Change in myocardial perfusion was assessed by 201Tl scintigraphy. In patients participating in the intervention group, body weight decreased by 5% (p less than 0.001), total cholesterol by 10% (p less than 0.001), and triglycerides by 24% (p less than 0.001); high density lipoproteins increased by 3% (p = NS). Physical work capacity improved by 23% (p less than 0.0001), and myocardial oxygen consumption, as estimated from maximal rate-pressure product, by 10% (p less than 0.05). Stress-induced myocardial ischemia decreased concurrently, indicating improvement of myocardial perfusion. Based on minimal lesion diameter, progression of coronary lesions was noted in nine patients (23%), no change in 18 patients (45%), and regression in 13 patients (32%). In the control group, metabolic and hemodynamic variables remained essentially unchanged, whereas progression of coronary lesions was noted in 25 patients (48%), no change in 18 patients (35%), and regression in nine patients (17%). These changes were significantly different from the intervention group (p less than 0.05).

CONCLUSIONS

In patients participating in regular physical exercise and low-fat diet, coronary artery disease progresses at a slower pace compared with a control group on usual care.

Improved stenosis geometry by quantitative coronary arteriography after vigorous risk factor modification

This study is a randomized, controlled, blinded, arteriographic trial to determine the effects of a low-cholesterol, low-fat, vegetarian diet, stress management and moderate aerobic exercise on geometric dimensions, shape and fluid dynamic characteristics of coronary artery stenoses in humans. Complex changes of different primary stenosis dimensions in opposite directions or to different degrees cause stenosis shape change with profound effects on fluid dynamic severity, not accounted for by simple percent narrowing. Accordingly, all stenosis dimensions were analyzed, including proximal, minimal, distal diameter, integrated length, exit angles and exit effects, determining stenosis shape and a single integrated measure of stenosis severity, stenosis flow reserve reflecting functional severity. In the control group, complex shape change and a stenosis-molding characteristic of statistically significant progressing severity occurred with worsening of stenosis flow reserve. In the treated group, complex shape change and stenosis molding characteristic of significant regressing severity was observed with improved stenosis flow reserve, thereby documenting the multidimensional characteristics of regressing coronary artery disease in humans.

Minimum heart rate and coronary atherosclerosis: independent relations to global severity and rate of progression of angiographic lesions in men with myocardial infarction at a young age

The relations of hemodynamic factors, plasma fibrinogen concentration, serum lipoprotein levels, and clinical risk indicators to coronary atherosclerosis were studied in 56 men who had survived a first myocardial infarction before the age of 45 years and who subsequently underwent two coronary angiographies with an intervening time interval of 4 to 7 years. Presence, severity, and rate of progression of both diffuse lesions and distinct stenoses were determined by means of separate classification systems in 15 proximal coronary arterial segments. High minimum heart rate measured during a 24-hour period in connection with the reangiography was associated with progression of both diffuse lesions and distinct stenoses. High minimum heart rate also correlated positively with angiographic scores of global severity of diffuse atherosclerosis and stenoses. Progression of disease was predicted independently by minimum heart rate and low-density lipoprotein/high-density lipoprotein ratio, whereas lipoprotein A, fibrinogen levels, hypertension, smoking, and beta-adrenergic receptor blockade treatment did not discriminate between patients with and without progression.

Lipoproteins and their genetic variation in subjects with and without angiographically verified coronary artery disease

To examine the concentration of serum lipoproteins and the association of their genetic variation with the occurrence of coronary artery disease (CAD), composite serum lipoprotein profiles including lipoprotein(a) (Lp[a]), apolipoprotein (apo) E phenotypes, and apo B Xba I genotypes were determined in patients with angiographically verified CAD (CAD+ group, n = 111) and in subjects with no angiographic evidence of CAD (CAD- group, n = 46). In addition, we determined the concentrations of serum lipids, lipoproteins, and apolipoproteins in 96 healthy controls. Both CAD- and CAD+ groups had lower concentrations of apos A-I and A-II but higher concentrations of serum total and very low density lipoprotein triglyceride and very low density lipoprotein cholesterol than did healthy controls. The mean concentrations of serum total and low density lipoprotein cholesterol and the median values of Lp(a) were similar in the CAD+ and CAD- groups, both having higher concentrations of low density lipoprotein cholesterol and apo B than the healthy controls. Irrespective of gender, patients with CAD had significantly lower serum high density lipoprotein cholesterol than did those without CAD (1.48 +/- 0.40 versus 1.16 +/- 0.29 mmol/l, p less than 0.001). In women, the mean serum total and very low density lipoprotein triglyceride concentration was also higher in the CAD+ than in the CAD- group. The frequency of the apo E4 allele (epsilon 4) was significantly higher in the CAD+ group (0.293) than in the CAD- group (0.174; p less than 0.001). The frequencies of the two apo B alleles, X1 (Xba I restriction site absent) and X2 (Xba I restriction site present), were similar in the two groups. Stepwise discriminant analysis revealed that in men, serum high density lipoprotein cholesterol had the highest power to discriminate for CAD. In addition, the concentration of plasma apo B levels and the occurrence of apo E phenotypes were independently associated with CAD in men. In women, the only independent factor associated with CAD after adjustment for beta-blocker and diuretics usage was the concentration of serum triglycerides.

Laboratory facilities for investigating lipid disorders in the United Kingdom: results of the British Hyperlipidaemia Association survey

AIMS

To determine the availability of facilities for the investigation of hyperlipidaemia in the United Kingdom.

METHODS

A questionnaire was sent to all health districts in the United Kingdom.

RESULTS

The response rate was 81%. All laboratories used enzymatic techniques to measure serum triglyceride and cholesterol concentrations, although there were differences in standardisation procedures. Reference ranges for serum lipids were quoted by 58% of laboratories while 50% quoted "desirable limits". Almost half specified that fasting blood samples were required. High density lipoprotein cholesterol concentrations were estimated by 75% and apolipoproteins AI and B by 14% of laboratories; there were differences in specimen type and considerable diversity in procedures used for measurement.

CONCLUSIONS

Many laboratories were unaware of current recommendations for screening for hypercholesterolaemia in the community. The present survey indicated an urgent need for the introduction of better reference methods, standardisation, and quality assurance procedures before apolipoproteins become a routine part of coronary heart disease risk assessment.

Myocardial perfusion and regression of coronary artery disease in patients on a regimen of intensive physical exercise and low fat diet

This intervention program tested the applicability and effects of intensive physical exercise and a low fat diet on progression of coronary atherosclerotic lesions and stress-induced myocardial ischemia in patients with stable angina pectoris. Eighteen patients participated in this program for 1 year; they consumed a low fat, low cholesterol diet (less than 20 energy % fat, cholesterol less than 200 mg/day) and exercised for greater than 3 h/week. Change in coronary morphology was assessed by angiography and digital image processing; stress-induced myocardial ischemia was measured by thallium-201 scintigraphy. Results were compared with those in patients receiving "usual care." In the intervention group, significant regression of coronary atherosclerotic lesions was noted in 7 of the 18 patients; no change or progression was present in 11 patients. In patients receiving usual care, regression was detected in only 1, with no change or progression in 11 patients (different from intervention, p less than 0.05). There was a significant reduction in stress-induced myocardial ischemia, which was not limited to patients with regression of coronary atherosclerotic lesions. Thus, regular physical exercise and a low fat diet may retard progression of coronary artery disease; however, improvement of myocardial perfusion may be achieved independently from regression of stenotic lesions.

A multicenter double-blind study comparing lovastatin and gemfibrozil in the treatment of primary hypercholesterolemia

The efficacy and tolerability of lovastatin and gemfibrozil were compared in a randomized double-blind 12-week study including 182 patients with primary hypercholesterolemia, from 7 hospitals in Spain. Inclusion criteria were total-cholesterol of at least 250 mg/dl and triglycerides less than 350 mg/dl. Patients were stratified in two groups: group 1, cholesterol less than 300 mg/dl, and group II, cholesterol equal to or more than 300 mg/dl. Patients were randomized to gemfibrozil (600 mg b.i.d.) or lovastatin (20 mg q.p.m., group I and 40 mg q.p.m., group II). If after 6 weeks of treatment cholesterol remained above 200 mg/dl, lovastatin does were doubled. In group I, lovastatin decreased cholesterol by 20%, LDL-C by 28%, and triglycerides by 17%, and increased HDL-C by 8%. In group II the results were: -26%, -33%, -19% and +6% respectively. The corresponding results with gemfibrozil were: -8%, -9%, -28% and +14% (group I); and -13%, -14%, -33% and +9% (group II). In both groups, lovastatin was more effective in reducing cholesterol and LDL-C (P less than 0.001) and gemfibrozil in reducing triglycerides (P less than 0.05 group I and P less than 0.01 group II). Both drugs were well tolerated. Thus, lovastatin and gemfibrozil are effective lipid-lowering agents; lovastatin has more pronounced effects in patients with hypercholesterolemia.

Relationship of skeletal muscle fiber type to serum high density lipoprotein cholesterol and apolipoprotein A-I levels

We measured the percentage of slow-twitch (ST) muscle fibers in the lateral portion of the quadriceps femoris muscle in 41 healthy sedentary male controls, 35 active male joggers, and 26 male coronary heart disease (CHD) patients. We then compared these percentages with serum levels of total cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I (apo A-I) found in these 102 middle-aged men. The percentage of ST muscle fibers in all men correlated positively with serum HDL-C (r = 0.57, P less than 0.001) and with apo A-I (r = 0.60, P less than 0.001) and negatively with triglycerides (r = -0.43, P less than 0.001). The proportion of ST fibers in joggers (65%; 61-69%, 95% confidence interval) was higher (P less than 0.001) than in sedentary controls (48%; 44-52%) or in CHD patients (44%; 39-49%). Moreover, 89% of the joggers had a proportion of ST fibers higher than 50%, whilst in sedentary controls and in CHD patients these values were 46% and 38%, respectively. Positive correlations were found between the percentage of ST fibers and both HDL-C and apo A-I in controls (r = 0.33, P less than 0.05 and r = 0.34, P less than 0.05) and in joggers (r = 0.46, P less than 0.01, and r = 0.40, P less than 0.05), respectively. Negative correlations in controls (r = -0.34, P less than 0.05) and in CHD patients (r = -0.43, P less than 0.05) were also found between the percentage of ST fibers and serum TG.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors influencing the formation of new human coronary lesions: age, blood pressure, and blood cholesterol

BACKGROUND

The Cholesterol Lowering Atherosclerosis Study, a controlled angiographic trial, has reported that new native coronary artery lesions are significantly reduced by aggressive blood lipid lowering therapy with colestipol plus niacin. To study factors relevant to primary atherosclerosis prevention, we have conducted an epidemiologic analysis of new native coronary lesion formation in placebo-treated patients.

METHODS

Univariate and multivariate logistic regression procedures were used to examine age at entry into the study, number of years since bypass, body weight, diastolic and systolic blood pressure, plasma total cholesterol, triglycerides, HDL-cholesterol, LDL-cholesterol, non-HDL-cholesterol, and apolipoproteins A-I,B, and C-III.

RESULTS

Significant univariate protective factors were older age (P less than .006), reduction of total plasma cholesterol (P less than .040), and systolic (P less than .024) and diastolic (P less than .022) blood pressure. Significant multivariate protective factors were older age (P less than .005) and reduction in systotic blood pressure (P less than .021). Blood pressure effects were not associated with use of specific antihypertensive agents.

CONCLUSIONS

These data provide additional support for the control of hypertension and reduction of blood cholesterol level for primary and secondary ischemic heart disease prevention. They also indicate the existence of a population at high risk for early coronary lesion formation and the need for improved means to identify such individuals prior to the onset of clinical manifestations of ischemic heart disease.

Angiographic evolution of coronary atherosclerosis in patients receiving propranolol. A two-year follow-up

STUDY OBJECTIVE

To test whether propranolol may influence the progression of coronary atherosclerosis.

DESIGN

Repeat coronary angiography after two year treatment and evaluation of changes in coronary narrowings.

SETTING

Subjects with effort angina of recent onset requiring coronary angiography and medical treatment.

PATIENTS

80 untreated patients, with a greater than or equal to 50 percent focal narrowing on a major coronary branch associated or not with a less than 50 percent stenosis of other major branches. They were randomized to isosorbide dinitrate (40 mg bid) (group 1, control group) or to propranolol (80 mg qid) (group 2, treatment group).

RESULTS

At restudy, there were more diseased vessels and These narrowings per patient in both groups. Multivessel involvement and greater than or equal to 50 percent obstructions were also augmented. These changes were not statistically significant. Patients with progression of the stenotic tracts (both greater than or equal to 50 percent and less than 50 percent were 19 (48 percent) in group 1 and 28 (70 percent) in group 2 (p less than 0.05). Narrowings with progression were 25 in group 1 and 48 in group 2. Thirteen narrowings in group 1 and 15 in group 2 were newly detected at restudy. Eighteen patients (45 percent) in group 1 and nine (23 percent) in group 2 had a steady disease. Smoking, high blood pressure, family history of coronary disease, blood glucose values and lipid levels were considered; the only significant group differences were 31 percent rise of total triglyceride and 23 percent decrease of HDL cholesterol in patients who were treated with propranolol.

CONCLUSIONS

Propranolol showed an adverse influence on coronary atherosclerosis, regarding the evolution of both greater than or equal to 50 percent and less than 50 percent narrowings and not the formation of new stenoses. Changes in serum lipid values might have a role.

Report of the Canadian Cardiovascular Society's consensus conference on the Management of the Postmyocardial Infarction Patient

In October 1989, the Canadian Cardiovascular Society announced a program to achieve consensus on important issues in the care of patients with cardiovascular disease. This report on the management of the postmyocardial infarction patient represents the first in a series of these consensus conferences. The process for establishing consensus recommendations involved several steps. A primary panel of 11 experts from various fields was selected to review the available clinical evidence and to make a list of recommendations about management decisions in the postmyocardial infarction period. The initial report was distributed to a secondary panel of 16 reviewers* representing allied health care constituencies from across Canada. On the basis of the critical reviews and feedback from these reviewers, a revised report was distributed to all members (over 800) of the Canadian Cardiovascular Society for further review and feedback. This iterative approach resulted in a penultimate report that was presented at a plenary session of the annual scientific meeting of the Canadian Cardiovascular Society on Oct. 18, 1990, in Halifax, NS. On the basis of discussion and feedback from this symposium, the consensus review was completed.

Improvement in the regulation of cellular cholesterologenesis in diabetes: the effect of reduction in serum cholesterol by simvastatin

Cellular cholesterol homeostasis was examined in 11 hypercholesterolaemic Type 2 diabetic patients prior to and following reduction of serum cholesterol using simvastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase. Following 12 weeks of treatment with simvastatin (10-40 mg day-1), serum cholesterol decreased by 30 +/- 3% from 7.8 +/- 0.2 mmol l-1 to 5.5 +/- 0.2 mmol l-1 (p less than 0.001) and LDL-cholesterol by 35 +/- 4% from 5.7 +/- 0.2 to 3.6 +/- 0.1 mmol l-1 (p less than 0.001). The esterified/free cholesterol ratio in LDL also decreased from 2.75 +/- 0.18 to 1.94 +/- 0.10 (p less than 0.01) after treatment. Cellular cholesterol synthesis, measured by [14C] acetate incorporation into mononuclear leucocytes, decreased by 39 +/- 11% from 231 +/- 13 to 140 +/- 25 mumol g-protein-1 (p less than 0.01). The degree of suppression of [14C]acetate incorporation into cholesterol in normal mononuclear cells by diabetic patients' LDL increased from 32.1 +/- 4.0% to 48.8 +/- 2.5% (p less than 0.001) following simvastatin. The activity of acyl coenzyme A:cholesterol-0-acyltransferase (ACAT) increased significantly by 55 +/- 18% (p less than 0.05) after treatment. Cholesterol synthesis in patients' mononuclear cells correlated positively (r = 0.66, p less than 0.05) with the esterified/free cholesterol ratio of their LDL, while suppression of cholesterol synthesis by patients' LDL correlated negatively (r = -0.64, p less than 0.05) with the esterified/free cholesterol ratio of the LDL following treatment.(ABSTRACT TRUNCATED AT 250 WORDS)