Familial hypercholesterolemia. What the zebra can teach us about the horse

Correlating corneal arcus with atherosclerosis in familial hypercholesterolemia

BACKGROUND

A relationship between corneal arcus and atherosclerosis has long been suspected but is controversial. The homozygous familial hypercholesterolemia patients in this study present a unique opportunity to assess this issue. They have both advanced atherosclerosis and corneal arcus.

METHODS

This is a cross-sectional study of 17 patients homozygous for familial hypercholesterolemia presenting to the Clinical Center of the National Institutes of Health. Plasma lipoproteins, circumferential extent of arcus, thoracic aorta and coronary calcific atherosclerosis score, and Achilles tendon width were measured at the National Institutes of Health.

RESULTS

Patients with corneal arcus had higher scores for calcific atherosclerosis (mean 2865 compared to 412), cholesterol-year score (mean 11830 mg-yr/dl compared to 5707 mg-yr/dl), and Achilles tendon width (mean 2.54 cm compared to 1.41 cm) than those without. Corneal arcus and Achilles tendon width were strongly correlated and predictive of each other. Although corneal arcus was correlated with calcific atherosclerosis (r = 0.67; p = 0.004), it was not as highly correlated as was the Achilles tendon width (r = 0.855; p < 0.001).

CONCLUSION

Corneal arcus reflects widespread tissue lipid deposition and is correlated with both calcific atherosclerosis and xanthomatosis in these patients. Patients with more severe arcus tend to have more severe calcific atherosclerosis. Corneal arcus is not as good an indicator of calcific atherosclerosis as Achilles tendon thickness, but its presence suggests increased atherosclerosis in these hypercholesterolemic patients.

Pharmacogenetics of HMG-CoA reductase inhibitors: exploring the potential for genotype-based individualization of coronary heart disease management

Despite the benefit of statin therapy in the prevention of coronary heart disease, a considerable inter-individual variation exists in its response. It is well recognized that genetic variation can contribute to differences in drug disposition and, consequently, clinical efficacy at the population level. Pharmacogenetics, exploring genetic polymorphisms that influence response to drug therapy, may one day allow the clinician to customize treatment strategies for patients in order to improve the success rate of drug therapies. To date, 41 studies have investigated the relationships between common genetic variants and response to statin therapy in terms of lipid effects and clinical outcomes; 16 candidate genes involved in lipoprotein metabolism and 3 in pharmacokinetics. APOE is the most extensively studied locus, and absolute difference in LDL cholesterol reduction across genotypes remained 3-6%. Moreover, none of the associations was striking enough to justify genetic analysis in clinical practice. Reported data have suggested that larger studies (>1000 participants) or combination analyses with >2 different polymorphisms would enable us to find clinically or biologically meaningful difference, which could be assumed as >10% absolute difference, and that genes influencing cholesterol biosynthesis in the liver, such as ABCG5/G8, CYP7A1, HMGCR, would be good candidates for future studies.

Cumulative effects of high cholesterol levels, high blood pressure, and cigarette smoking on carotid stenosis

BACKGROUND

Single measurements of cardiovascular risk factors may not accurately reflect a person's past exposure to those risk factors. We therefore studied the long-term associations of cardiovascular risk factors such as high serum cholesterol levels, high blood pressure, and cigarette smoking with the prevalence of carotid stenosis.

METHODS

We studied cross-sectional and longitudinal information from a sample of 429 men and 661 women in the Framingham Heart Study who underwent B-mode ultrasound measurements of the carotid artery. Their mean age was 75 years, and each had attended most of the biennial clinic examinations over the 34 years before the carotid ultrasound study. We used time-integrated measurements to assess the associations between various cardiovascular risk factors and the degree of carotid stenosis.

RESULTS

Moderate carotid stenosis (> or =25 percent) was present in 189 men and 226 women. We assessed the odds ratios for this degree of stenosis as compared with minimal stenosis (<25 percent) according to increases in risk factors. In the men, the odds ratio for moderate carotid stenosis associated with an increase of 20 mm Hg in systolic blood pressure was 2.11 (95 percent confidence interval, 1.51 to 2.97). The odds ratio for an increase of 10 mg per deciliter (0.26 mmol per liter) in the cholesterol level was 1.10 (95 percent confidence interval, 1.03 to 1.16), and for an increase of five pack-years of smoking it was 1.08 (95 percent confidence interval, 1.03 to 1.13). The results were similar in the women. Time-integrated measurements of diastolic blood pressure showed significant associations with carotid stenosis in men and insignificant associations in women.

CONCLUSIONS

Over the long term, high systolic blood pressure, high cholesterol levels, and smoking were associated with an increased risk of carotid stenosis in this elderly population.