Coronary disease in familial hypercholesterolemia

A Case of Premature Triple Vessel Coronary Artery Disease and Valvular Degeneration: A Rare Presentation of Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is one of the inherited causes of coronary artery disease (CAD) and causes calcific valvular degeneration in rare cases. A 13-year-old boy with multiple xanthomas presented with severe chest pain, shortness of breath, and sweating. He was diagnosed with premature CAD leading to non-ST-elevation myocardial infarction, secondary to early-onset FH [severely raised low-density lipoprotein (LDL) and triglycerides (TG) on lipid profile]. CT angiogram showed triple vessel disease, and echocardiogram revealed tight aortic stenosis. Percutaneous coronary angioplasty was done, and valvuloplasty was planned on the follow-up assessment. Early diagnosis and prompt management could have prevented these complications.

Why patients with familial hypercholesterolemia are at high cardiovascular risk? Beyond LDL-C levels

Familial hypercholesterolemia (FH) is a common genetic cause of elevated low-density lipoprotein cholesterol (LDL-C) due to defective clearance of circulating LDL particles. All FH patients are at high risk for premature cardiovascular disease (CVD) events due to their genetically determined lifelong exposure to high LDL-C levels. However, different rates of CVD events have been reported in FH patients, even among those with the same genetic mutations and comparable LDL-C levels. Hence, additional CVD risk modifiers, beyond LDL-C, may contribute to increase CVD risk in the FH population. In this review, we discuss the overall CVD risk burden of the FH population. Additionally, we revise the prognostic impact of several traditional and emerging predictors of CVD risk and we provide an overview of the role of specific tools to stratify CVD risk in FH patients in order to ensure them a more personalized treatment approach.

The Role of Emerging Risk Factors in Cardiovascular Outcomes

PURPOSE OF REVIEW

This review discusses the recent evidence for a selection of blood-based emerging risk factors, with particular reference to their relation with coronary heart disease and stroke.

RECENT FINDINGS

For lipid-related emerging risk factors, recent findings indicate that increasing high-density lipoprotein cholesterol is unlikely to reduce cardiovascular risk, whereas reducing triglyceride-rich lipoproteins and lipoprotein(a) may be beneficial. For inflammatory and hemostatic biomarkers, genetic studies suggest that IL-6 (a pro-inflammatory cytokine) and several coagulation factors are causal for cardiovascular disease, but such studies do not support a causal role for C-reactive protein and fibrinogen. Patients with chronic kidney disease are at high cardiovascular risk with some of this risk not mediated by blood pressure. Randomized evidence (trials or Mendelian) suggests homocysteine and uric acid are unlikely to be key causal mediators of chronic kidney disease-associated risk and sufficiently large trials of interventions which modify mineral bone disease biomarkers are unavailable. Despite not being causally related to cardiovascular disease, there is some evidence that cardiac biomarkers (e.g. troponin) may usefully improve cardiovascular risk scores. Many blood-based factors are strongly associated with cardiovascular risk. Evidence is accumulating, mainly from genetic studies and clinical trials, on which of these associations are causal. Non-causal risk factors may still have value, however, when added to cardiovascular risk scores. Although much of the burden of vascular disease can be explained by 'classic' risk factors (e.g. smoking and blood pressure), studies of blood-based emerging factors have contributed importantly to our understanding of pathophysiological mechanisms of vascular disease, and new targets for potential therapies have been identified.

Enhanced status of inflammation and endothelial activation in subjects with familial hypercholesterolaemia and their related unaffected family members: a case control study

Background

Familial hypercholesterolaemia (FH) leads to premature coronary artery diseases (CAD) which pathophysiologically can be measured by inflammation, endothelial activation and oxidative stress status. However, the status of these biomarkers among related unaffected relatives of FH cases and whether FH is an independent predictor of these biomarkers have not been well established. Thus, this study aims to (1) compare the biomarkers of inflammation, endothelial activation and oxidative stress between patients with FH, their related unaffected relatives (RUC) and normolipaemic subjects (NC) (2)determine whether FH is an independent predictor of these biomarkers.

Methods

One hundred thirty-one FH patients, 68 RUC and 214 matched NC were recruited. Fasting lipid profile, biomarkers of inflammation (hsCRP), endothelial activation (sICAM-1 and E-selectin) and oxidative stress [oxidized LDL (oxLDL), malondialdehyde (MDA) and F2-isoprostanes (ISP)] were analyzed and independent predictor was determined using binary logistic regression analysis.

Results

hsCRP was higher in FH and RUC compared to NC (mean ± SD = 1.53 ± 1.24 mg/L and mean ± SD = 2.54 ± 2.30 vs 1.10 ± 0.89 mg/L, p < 0.05). sICAM-1 and E-selectin were higher in FH compared to NC (mean ± SD = 947 ± 742 vs 655 ± 191 ng/mL, p < 0.001 and 175 ± 131 vs 21.6 ± 10.7 ng/mL, p < 0.001 respectively) while sICAM-1 concentration was higher in RUC compared to NC (mean ± SD = 945 ± 379 vs 655 ± 191 ng/mL, p < 0.01). Biomarkers of oxidation (ox-LDL, MDA and ISP) were elevated in FH compared to NC [mean ± SD = (48.2 ± 26.8 vs 27.3 ± 13.2 mU/L, p < 0.001), (2.57 ± 1.3 vs 1.20 ± 0.30 nmol/mL, p < 0.001) and (645 ± 396 vs 398 ± 20.5 pg/L, p < 0.001) respectively], but no significant differences were observed between RUC and NC (p > 0.05). FH was an independent predictor for sICAM-1 (p = 0.007), ox-LDL (p < 0.001) and MDA (p < 0.001) while RUC independently predicted for sICAM-1 (p < 0.001).

Conclusion

The screening for FH is vital as all biomarkers associated with atherogenesis are higher in these subjects and FH also independently predict biomarkers of endothelial activation and oxidative stress. Furthermore, despite not fulfilling the diagnostic criteria for FH, related unaffected family members that may not phenotypically express the mutation may still be at risk of developing CAD as reflected from the enhanced inflammatory and endothelial activation status observed in this group. This highlights the need to not only conduct family tracing in indexed FH cases, but also assess the coronary risk among family members that do not fulfil the FH diagnostic criteria.

Long-Term Risk of Atherosclerotic Cardiovascular Disease in US Adults With the Familial Hypercholesterolemia Phenotype

BACKGROUND

Heterozygous familial hypercholesterolemia (FH) affects up to 1 in 200 individuals in the United States, but atherosclerotic cardiovascular disease (ASCVD) outcomes of FH in the general US population have not been described. We therefore sought to evaluate long-term coronary heart disease (CHD) and total ASCVD risks in US adults with an FH phenotype.

METHODS

Using individual pooled data from 6 large US epidemiological cohorts, we stratified participants by low-density lipoprotein cholesterol level at index ages from 20 to 79 years. For the primary analysis, low-density lipoprotein cholesterol levels ≥190 and <130 mg/dL defined the FH phenotype and referent, respectively. Sensitivity analyses evaluated the effects of varying the FH phenotype definition. We used Cox regression models to assess covariate-adjusted associations of the FH phenotype with 30-year hazards for CHD (CHD death or nonfatal myocardial infarction) and total ASCVD (CHD or stroke).

RESULTS

We included 68 565 baseline person-examinations; 3850 (5.6%) had the FH phenotype by the primary definition. Follow-up across index ages ranged from 78 985 to 308 378 person-years. After covariate adjustment, the FH phenotype was associated with substantially elevated 30-year CHD risk, with hazard ratios up to 5.0 (95% confidence interval, 1.1-21.7). Across index ages, CHD risk was accelerated in those with the FH phenotype by 10 to 20 years in men and 20 to 30 years in women. Similar patterns of results were found for total ASCVD risk, with hazard ratios up to 4.1 (95% confidence interval, 1.2-13.4). Alternative FH phenotype definitions incorporating family history, more stringent age-based low-density lipoprotein cholesterol thresholds, or alternative lipid fractions decreased the FH phenotype prevalence to as low as 0.2% to 0.4% without materially affecting CHD risk estimates (hazard ratios up to 8.0; 95% confidence interval, 1.0-61.6).

CONCLUSIONS

In the general US population, the long-term ASCVD burden related to phenotypic FH, defined by low-density lipoprotein cholesterol ≥190 mg/dL, is likely substantial. Our finding of CHD risk acceleration may aid efforts in risk communication.

The role of oxidative stress in alterations of hematological parameters and inflammatory markers induced by early hypercholesterolemia

AIMS

The investigation of the effects of a high cholesterol diet (HD) for a short-time period on hematological parameters and the potential role of oxidative stress and inflammation markers.

MAIN METHODS

Rabbits were fed either a control diet or a diet containing 1% cholesterol (HD) for 5-6 weeks. The plasma lipid levels, C reactive protein (CRP), total red blood cells (RBC), total white blood cells (WBC), platelet count, packed cell volume (PCV) and leukocyte formula were determined. Oxidative stress was evaluated by the thiobarbituric acid reactive substances (TBARS), total glutathione and GSH serum level measurements. The osmotic fragility and the membrane fluidity of erythrocytes were determined. The levels of total cholesterol and TBARS were also measured in the erythrocyte membrane suspension.

KEY FINDINGS

A decrease in the RBC and PCV was observed in rabbits fed on HD. The membrane rigidity and osmotic fragility were increased, and the morphological changes caused by the HD and TBARS levels in the erythrocyte membrane may account for this phenomenon. The inflammatory markers as the CRP levels, the platelet count, the WBC and the neutrophils were increased. The TBARS and GSH levels in the serum were increased and decreased, respectively.

SIGNIFICANCE

This study shows that feeding rabbits an HD for a short time induces hematological alterations, disturbances in the oxidant-antioxidant balance and an increase of inflammatory markers. These findings support the importance of the early correction or prevention of high cholesterol levels to disrupt the process leading to the development of cardiovascular diseases.

Multicenter study to determine the diagnosis criteria of heterozygous familial hypercholesterolemia in Japan

AIM

Heterozygous patients of familial hypercholesterolemia (FH) are known to have a high risk of coronary artery disease (CAD). Early diagnosis and prompt treatment are necessary to prevent their CAD. In this study we tried to amend the Japanese diagnostic criteria of FH for general practitioners by examining each component of the current criteria.

METHODS

A multicenter study was performed, which included 1356 dyslipidemic patients at 6 centers. Pretreatment demographic information including LDL-cholesterol (LDL-C), Achilles tendon thickness (ATT), family history of FH and premature CAD and the result of genetic analysis were analyzed.

RESULTS

Of 1356 patients, 419 were diagnosed with FH by criteria in 1988, which were used as a golden standard. We tried to define FH according to 3 conventional major items, i.e., 1) LDL-C, 2) ATT and/or cutaneous nodular xanthomas (CX), 3) family history of FH and/or family history of premature CAD. We then determined the cutoff of LDL-C using the new criteria. When we used 180 mg/dL as the cutoff of LDL-C, 94.3% of FH patients and 0.85% of non-FH satisfied 2 or more criteria. When we used 190 mg/dL, 92.1% of FH and 0.85% of non-FH satisfied 2 or more criteria; therefore, we chose 180 mg/dL for the cutoff of LDL-C in the new criteria and proposed that the diagnosis of definite FH can be made if 2 or more criteria are satisfied.

CONCLUSIONS

We examined each component for the diagnosis of heterozygous FH in a multicenter study in Japan.