Hypertriglyceridemia: its etiology, effects and treatment.

Elevated plasma triglyceride concentration is a common biochemical finding, but the evidence for the benefit of treating this lipid disturbance remains less robust than that for treating elevated low-density lipoprotein-cholesterol. Part of the difficulty in the provision of specific recommendations has been the frequent coexistence of elevated triglycerides with other conditions that affect cardiovascular disease risk, such as depressed high-density lipoprotein-cholesterol, obesity, metabolic syndrome, proinflammatory and prothrombotic biomarkers, and type 2 diabetes. Recent investigations of outcomes of cardiovascular disease when medications are used to reduce triglyceride levels suggest that, although a net benefit probably exists, both relative and absolute risk reductions seem underwhelming when compared with the benefit of reducing low-density lipoprotein-cholesterol levels with treatment. However, the totality of evidence suggests that elevated triglyceride levels likely contribute independently to increased risk of cardiovascular disease, although there is no consensus about appropriate target levels. Furthermore, severe hypertriglyceridemia is associated with an increased risk of acute pancreatitis, irrespective of its effect on risk of cardiovascular disease. We review the causes and classification of elevated triglyceride levels, the clinical manifestations of primary hypertriglyceridemia and the management of patients with elevated triglyceride levels.

Relationship of the metabolic syndrome to carotid ultrasound traits.

BACKGROUND: The metabolic syndrome is associated with increased vascular disease risk. We evaluated two carotid ultrasound measurements, namely intima media thickness and total plaque volume, in a Canadian Oji-Cree population with a high metabolic syndrome prevalence rate. METHODS: As part of the Sandy Lake Complications Prevalence and Risk Factor Study, 166 Oji-Cree subjects (baseline metabolic syndrome prevalence, 44.0%, according to the National Cholesterol Education Program Adult Treatment Panel III guidelines) were examined using a high-resolution duplex ultrasound scanner. RESULTS: Image analysis showed that mean intima media thickness was elevated in subjects with the metabolic syndrome (818 +/- 18 vs 746 +/- 20 microm), as was total plaque volume (125 +/- 26 vs 77.3 +/- 17.0 mm3). However, after adjustment for age and sex, the differences were significant only for intima media thickness (P = 0.039). Furthermore, a significant trend towards increased intima media thickness was observed with increasing numbers of metabolic syndrome components: mean intima media thickness was highest among individuals with all five metabolic syndrome components compared to those with none (866 +/- 55 vs 619 +/- 23 microm, P = 0.0014). A similar, but non-significant trend was observed for total plaque volume. CONCLUSION: This is the first study of the relationship between the metabolic syndrome and two distinct carotid ultrasound traits measured in the same individuals. The results suggest that standard intima media thickness measurement shows a more consistent and stronger association with the metabolic syndrome than does total plaque volume.

Disparate associations of a functional promoter polymorphism in PCK1 with carotid wall ultrasound traits.

BACKGROUND AND PURPOSE: Cytosolic phosphoenolpyruvate carboxykinase (PEPCK; EC 4.1.1.32), encoded by PCK1, catalyzes the first committed step in gluconeogenesis. We previously showed that a -232C>G promoter polymorphism within a cis-acting element required for basal and cAMP-mediated PCK1 gene transcription results in loss of negative regulation by insulin, contributing to worsened metabolic control in the context of insulin resistance. We hypothesized that this polymorphism would be associated with carotid atherosclerosis in a sample of 150 aboriginal Canadians. METHODS: Dependent variables were 2 distinct carotid traits, namely intima-media thickness (IMT) assessed using B-mode ultrasound and total carotid plaque volume (TPV) assessed using 3D ultrasound. RESULTS: Multivariate analysis showed significant but opposite associations of PCK1 genotype with these traits. Specifically, subjects with the PCK1-232G/G genotype had more carotid IMT (0.80+/-0.02 versus 0.73+/-0.03 mm; P=0.007) but less TPV (0.10+/-0.09 versus 0.38+/-0.13; P=0.03) than subjects with other genotypes. CONCLUSIONS: The findings connect the key enzyme in gluconeogenesis with atherosclerosis. The meaning of the opposing associations of PCK1 genotype with IMT and TPV is unclear; more work is required to confirm whether these might be distinct quantitative traits with different biological determinants.

Genetic variation in PPARG encoding peroxisome proliferator-activated receptor gamma associated with carotid atherosclerosis.

BACKGROUND AND PURPOSE: Peroxisome proliferator-activated receptor gamma is a crucial molecule in atherogenesis because it is associated with metabolic risk factors such as obesity and diabetes and also plays a key role in subcellular metabolism of arterial wall macrophage foam cells. Genetic variation in PPARG has been associated with metabolic and cardiovascular end points. METHODS: We investigated the relationship between 2 common PPARG polymorphisms, namely P12A and c.1431C>T, and carotid atherosclerosis in a sample of 161 Canadian aboriginal people. Dependent variables were carotid intima media thickness (IMT), assessed using B-mode ultrasonography, and total carotid plaque volume (TPV), assessed using 3D ultrasound. RESULTS: Using multivariate analysis, we found that subjects with > or =1 PPARG A12 allele had less carotid IMT than others (0.72+/-0.03 versus 0.80+/-0.02 mm; P=0.0045), with no between-genotype difference in TPV. In contrast, subjects with the PPARG c.1431T allele had greater TPV than others (124+/-18.4 versus 65.1+/-23.7 mm3; P=0.0079), with no between-genotype difference in IMT. CONCLUSIONS: The findings show an association between PPARG genotypes and carotid arterial phenotypes, and further reflect the prevailing view that the PPARG A12 allele protects against deleterious phenotypes. Also, whereas IMT and TPV are somewhat correlated with each other, they might also represent distinct traits with discrete determinants representing different stages of atherogenesis.

Laminopathies and atherosclerosis.

Laminopathies are genetic diseases that encompass a wide spectrum of phenotypes with diverse tissue pathologies and result mainly from mutations in the LMNA gene encoding nuclear lamin A/C. Some laminopathies affect the cardiovascular system, and a few (namely, Dunnigan-type familial partial lipodystrophy [FPLD2] and Hutchinson-Gilford progeria syndrome [HGPS]) feature atherosclerosis as a key component. The premature atherosclerosis of FPLD2 is probably related to characteristic proatherogenic metabolic disturbances such as dyslipidemia, hyperinsulinemia, hypertension, and diabetes. In contrast, the premature atherosclerosis of HGPS occurs with less exposure to metabolic proatherogenic traits and probably reflects the generalized process of accelerated aging in HGPS. Although some common polymorphisms of LMNA have been associated with traits related to atherosclerosis, the monogenic diseases FPLD2 and HGPS are more likely to provide clues about new pathways for the general process of atherosclerosis. Dunnigan-type familial partial lipodystrophy and Hutchinson-Gilford progeria syndrome are laminopathies caused by mutation in LMNA that feature atherosclerosis, which is related to proatherogenic metabolic disturbances and to the generalized process of accelerated aging, respectively. These monogenic diseases may provide clues about new pathways for atherogenesis.