Intron 4 VNTR polymorphism of eNOS gene is protective for cardiac syndrome X.

Microvascular abnormalities caused by endothelial dysfunction seem to be responsible for the myocardial ischemia in patients with cardiac syndrome X (CSX). Nitric oxide is a key mediator of endothelial function and is synthesized by endothelial nitric oxide synthase (eNOS). We investigated if the 3 potential polymorphisms of the eNOS gene (VNTR in intron 4, T786C polymorphism in the promoter region, and G894T polymorphism in exon 7) are independent risk factors for CSX. Sixty-nine patients with CSX and 73 healthy controls were studied. Genotypes were determined through polymerase chain reaction with or without restriction endonuclease digestions. Genotype distribution was significantly different between patients with CSX and controls for intron 4aa (allele for 4 repeats of 27 bp), intron 4aa genotype frequency being 3.2% and 6.8%, respectively. The presence of intron 4a is 3.2 (odds ratio) times protective (95% confidence interval, 1.5-6.8) for the risk of CSX disease. The protective effect of intron 4a polymorphism also holds after adjustment for age and sex and when the study group is limited to those without hypertension and hyperlipidemia. No significant difference was observed in genotype distribution of G894T and T786C polymorphism between patients with CSX and controls. In conclusion, intron 4aa genotype of eNOS gene is protective for CSX. No association was found between promoter and exon 7 polymorphisms of eNOS gene and CSX.

Rho-kinase inhibition with intracoronary fasudil prevents myocardial ischemia in patients with coronary microvascular spasm.

OBJECTIVES: We sought to determine whether a potent Rho-kinase inhibitor fasudil prevents the occurrence of myocardial ischemia in patients with microvascular angina attributable to coronary microvascular spasm. BACKGROUND: Effective treatment of patients with angina who have normal coronary arteriograms (microvascular angina) has not yet been established. Rho-kinase-mediated calcium sensitization of the myosin light chain in smooth muscle cells has been implicated as substantially contributing to vascular hyperconstriction. METHODS: We studied consecutive 18 patients with angina and normal epicardial coronaries in whom intracoronary acetylcholine (ACh) induced myocardial ischemia (ischemic electrocardiographic changes, myocardial lactate production, or both) without angiographically demonstrable epicardial coronary vasospasm. All patients underwent a second ACh challenge test after pretreatment with either saline (n = 5) or fasudil (4.5 mg intracoronarily, n = 13). RESULTS: Myocardial ischemia was reproducibly induced by ACh in the saline group. In contrast, 11 of the 13 patients pretreated with fasudil had no evidence of myocardial ischemia during the second infusion of ACh (p < 0.01). The lactate extraction ratio (median value [interquartile range]) during ACh infusion was improved by fasudil pretreatment, from -0.16 (-0.25 to 0.04) to 0.09 (0.05 to 0.18) (p = 0.0125). CONCLUSIONS: Fasudil ameliorated myocardial ischemia in patients who were most likely having coronary microvascular spasm. The inhibition of Rho-kinase may be a novel therapeutic strategy for this group of patients with microvascular angina.

Reducing cardiovascular risk in diabetes. Which factors to modify first?

Up to 80% of diabetic patients die of macrovascular complications, including CAD, stroke, and peripheral vascular disease. Because of the growing numbers of diabetic patients and the increased mortality after their first cardiovascular event, it is critical to identify and treat risk factors early and aggressively in these patients. Numerous studies in patients with type 2 diabetes have shown the benefits of aggressive treatment of blood pressure and lipids to levels that 10 years ago would have seemed abnormally low. The downward changes in "normal" limits can be frustrating to primary care physicians, but advances in treatment are redefining "normal" levels required to avoid complications in this high-risk population.

Effect of orlistat-assisted weight loss in decreasing coronary heart disease risk in patients with syndrome X.

This study describes the changes in risk factors for coronary heart disease in obese persons with syndrome X after orlistat-assisted weight loss. Data were available for 1,700 patients who completed 52 weeks of weight loss; 128 were defined as having syndrome X by being in the quintile with the highest plasma triglyceride levels (>2.2 mM/L) and the lowest high-density lipoprotein cholesterol (HDL, <1.0 mM/L) concentrations. Initial characteristics of those with syndrome X were similar to the 119 subjects (non-syndrome X) in the lowest quintile of plasma triglyceride (<0.975 mM/L) and highest quintile of HDL cholesterol (>1.5 mM/L). Subjects were placed on a calorie-restricted diet, and randomized to receive orlistat or placebo. Initial values were higher in those with syndrome X for diastolic blood pressure (p = 0.03), plasma insulin (p = 0.0001), triglyceride (p = 0.0001) concentrations, and ratio of low-density lipoprotein cholesterol to HDL cholesterol (p = 0.0001), and were lower for HDL cholesterol (p = 0.001) concentrations. Weight loss was greater in both groups of orlistat-treated patients (p = 0.026); in those with syndrome X, it was associated with a significant reduction in plasma insulin (p = 0.019) and triglyceride (p = 0.0001) concentrations, an increase in HDL cholesterol concentration, and a decrease in low-density lipoprotein/HDL cholesterol ratio (p = 0.0001). There were no significant changes in plasma insulin, triglycerides, or HDL cholesterol concentration in the non-syndrome X group. In conclusion, weight loss attenuates coronary heart disease risk factors in obese persons with syndrome X, and the risk factor reduction is enhanced with administration of orlistat.

Prenatal high-dose pyridoxine may prevent hypertension and syndrome X in-utero by protecting the fetus from excess glucocorticoid activity.

The increased risk for hypertension, insulin resistance syndrome, and coronary events associated with small-for-gestational-age birth, has plausibly been attributed to excessive prenatal exposure to glucocorticoids; this may up-regulate glucocorticoid activity throughout life by permanently decreasing expression of hippocampal glucocorticoid receptors crucial for feedback control of cortisol secretion. Since pyridoxal phosphate is a safe physiological antagonist of glucocorticoid activity, it is proposed that prenatal supplementation with high-dose pyridoxine may counteract the adverse impact of glucocorticoids on fetal growth, as well as on subsequent cardiovascular risk.

Insulin resistance syndrome: options for treatment.

BACKGROUND: Insulin resistance is characterized by impaired responsiveness to endogenous or exogenous insulin. Loss of responsiveness is associated with a "clustering" of cardiovascular risk factors that includes abdominal obesity, hypertension, dyslipidemia, glucose intolerance, and hyperinsulinemia; this association is referred to as the insulin resistance syndrome (IRS). METHODS: We searched MEDLINE, using the term insulin resistance, and reviewed relevant publications. RESULTS: We review the mechanisms and clinical consequences attributed to IRS, along with patient assessment and treatment options. CONCLUSIONS: It is possible to improve insulin sensitivity by caloric restriction, weight loss, exercise, and drug therapy. Metformin and troglitazone, approved for use in the treatment of type 2 diabetes mellitus (DM), improve insulin sensitivity and lower plasma glucose concentrations. Several other medications that may improve insulin sensitivity are currently under clinical investigation. Studies are needed to determine the effect of these medications on morbidity and mortality of patients with insulin resistance and type 2 DM.

Reducing the incidence of coronary heart disease by managing hypertension: implications of syndrome X.

Syndrome X is a constellation of abnormalities; it appears to be strongly linked to insulin resistance and the risk of atherosclerosis. It consists of hypertension, glucose intolerance, obesity, dyslipidemia and, observed more recently, coagulation abnormalities. It is possible that treating blood pressure levels alone while ignoring or worsening other strongly associated risk factors has resulted in minimal effects on the incidence of coronary heart disease (CHD). Syndrome X has raised the awareness of these associated risk factors and has further led to the consideration of hypertension as a metabolic disease. The epidemiologic evidence in support of the link between insulin resistance and hypertension is reviewed, and the public health implications of these data are outlined.