Lipoprotein(a) and Cardiovascular Diseases - Revisited

Two decades ago, it was recognized that lipoprotein(a) (Lp(a)) concentrations were elevated in patients with cardiovascular disease (CVD). However, the importance of Lp(a) was not strongly established due to a lack of both Lp(a)-lowering therapy and evidence that reducing Lp(a) levels improves CVD risk. Recent advances in clinical and genetic research have revealed the crucial role of Lp(a) in the pathogenesis of CVD. Mendelian randomization studies have shown that Lp(a) concentrations are causal for different CVDs, including coronary artery disease, calcified aortic valve disease, stroke, and heart failure, despite optimal low-density lipoprotein cholesterol (LDL-C) management. Lp(a) consists of apolipoprotein (apo) B100 covalently bound to apoA. Thus, Lp(a) has atherothrombotic traits of both apoB (from LDL) and apoA (thrombo-inflammatory aspects). Although conventional pharmacological therapies, such as statin, niacin, and cholesteryl ester transfer protein, have failed to significantly reduce Lp(a) levels, emerging new therapeutic strategies using proprotein convertase subtilisin-kexin type 9 inhibitors or antisesnse oligonucleotide technology have shown promising results in effectively lowering Lp(a). In this review we discuss the revisited important role of L(a) and strategies to overcome residual risk in the statin era.

An elevated level of physical activity is associated with normal lipoprotein(a) levels in individuals from Maracaibo, Venezuela

Coronary artery disease is the main cause of death worldwide. Lipoprotein(a) [Lp(a)], is an independent risk factor for coronary artery disease in which concentrations are genetically regulated. Contradictory results have been published about physical activity influence on Lp(a) concentration. This research aimed to determine associations between different physical activity levels and Lp(a) concentration. A descriptive and cross-sectional study was made in 1340 randomly selected subjects (males = 598; females = 712) to whom a complete clinical history, the International Physical Activity Questionnaire, and Lp(a) level determination were made. Statistical analysis was carried out to assess qualitative variables relationship by chi2 and differences between means by one-way analysis of variance considering a P value <0.05 as statistically significant. Results are shown as absolute frequencies, percentages, and mean +/- standard deviation according to case. Physical activity levels were ordinal classified as follows: low activity with 24.3% (n = 318), moderate activity with 35.0% (n = 458), and high physical activity with 40.8% (n = 534). Lp(a) concentration in the studied sample was 26.28 +/- 12.64 (IC: 25.59-26.96) mg/dL. Lp(a) concentration according to low, moderate, and high physical activity levels were 29.22 +/- 13.74, 26.27 +/- 12.91, and 24.53 +/- 11.35 mg/dL, respectively, observing statistically significant differences between low and moderate level (P = 0.004) and low and high level (P < 0.001). A strong association (chi2 = 9.771; P = 0.002) was observed among a high physical activity level and a normal concentration of Lp(a) (less than 30 mg/dL). A lifestyle characterized by high physical activity is associated with normal Lp(a) levels.

Decrease of Lp(a) during weight reduction in obese children is modified by the apo(a) kringle-IV copy number variation

BACKGROUND

Lipoprotein(a) [Lp(a)] is considered an independent risk factor for cardiovascular disease. Its concentration is mainly determined by the kringle-IV repeat copy number variation (CNV) at the apolipoprotein(a) [apo(a)] locus.

OBJECTIVE

We aimed to investigate the immediate effect of weight reduction on plasma Lp(a) levels and its dependency on the apo(a) CNV in obese children.

DESIGN

We performed a prospective longitudinal intervention study of a low-fat hypocaloric diet conducted in a 3-week dietary camp for obese children. In all, 140 obese participants (54 boys and 86 girls) with a mean age of 12.5+/-1.6 years and a mean relative body mass index (BMI) before treatment of 165.6+/-24.7% were included. Body weight and plasma levels of Lp(a), lipids, apolipoproteins A-I and B, insulin, and C-reactive protein were determined before the onset and after the end of the intervention. In addition, the number of apo(a) kringle-IV repeats were determined using sodium dodecyl sulfate agarose gel electrophoresis.

RESULTS

The mean loss of body weight was 5.0+/-1.3 kg (-6.6%), resulting in a mean decrease of the relative BMI of 6.6%. Blood chemistry revealed significant changes in all parameters, especially in Lp(a), with a decrease from 24.4+/-30.6 to 17.9+/-22.6 mg per 100 ml or -19% (P<0.001). The decrease of Lp(a) levels was higher in the group with low compared with high molecular weight apo(a) phenotypes (-23.9 vs -16.6%).

CONCLUSIONS

Weight reduction in obese children is associated with significant changes in Lp(a) levels, especially in subjects with high pre-treatment Lp(a) concentrations. This effect is markedly influenced by the molecular phenotype at the copy-number variable apo(a) locus.

[Physical activity among aboriginals in Canada]

This paper summarizes available information on patterns of physical activity, their determinants and consequences, and the results of various interventions designed to increase the physical activity of Aboriginal peoples in Canada and the United States. There is a paucity of national data on this issue for Aboriginal peoples. The most recent data, from the First Nations Regional Longitudinal Health Survey of 2002-2003, indicate that 21% of adults (27% of men, 15% of women) were engaging in at least 30 min of moderate to vigorous physical activity on 4 d/week or more. The present paper highlights the unique challenges this group faces, underlining the need to integrate collective knowledge regarding how much physical activity is required for Aboriginal Canadians, and how this activity should be accomplished, to promote and maintain health. Efforts are currently underway to tailor Canada's physical activity guide for First Nations, Inuit, and Métis. Future research among Aboriginal groups should examine the minimal and optimal levels of physical activity required to achieve health benefits.

Relation of cardiorespiratory fitness to inflammatory markers, fibrinolytic factors, and lipoprotein(a) in patients with type 2 diabetes mellitus

Increased inflammation, fibrinolytic factors, and lipoprotein(a) (LP[a]) were associated with increased cardiovascular events in patients with type 2 diabetes, whereas higher levels of cardiorespiratory fitness (CRF) were associated with a lower incidence of cardiovascular mortality. Whether CRF is associated with inflammatory markers, fibrinolytic factors, and LP(a) in patients with type 2 diabetes was investigated. A total of 425 men with type 2 diabetes (mean age 55 +/- 8 years) who participated in a medical screening program were studied. CRF was measured using peak oxygen uptake with expired gas analysis during a symptom-limited exercise test. CRF inversely correlated with C-reactive protein (CRP; r = -0.27, p <0.05), white blood cell count (r = -0.13, p <0.05), fibrinogen (r = -0.28, p <0.05), LP(a) (r = -0.53, p <0.05), tissue plasminogen activator (t-PA) antigen (r = -0.65, p <0.05), and plasminogen activator inhibitor-1 activity (r = -0.17, p <0.05). Men in the highest tertile of CRF had significantly lower CRP, white blood cell count, fibrinogen, LP(a), and t-PA than men in the lowest tertile of CRF (all p <0.05). In separate multivariable linear regression models that adjusted for age, body mass index, smoking, lipid profiles, glucose, and systolic blood pressure, CRP (beta = -0.23, p <0.05), white blood cell count (beta = -0.16, p <0.05), fibrinogen (beta = -0.24, p <0.05), LP(a) (beta = -0.28, p <0.05), and t-PA (beta = -0.69, p <0.05) were each inversely associated with CRF. Each MET increment higher peak oxygen uptake was associated with a lower odds ratio of having abnormal LP(a) (odds ratio 0.43, 95% confidence interval 0.20 to 0.91) in a multivariate logistic regression model. In conclusion, CRF was inversely associated with inflammatory markers, fibrinolytic factors, and LP(a) in men with type 2 diabetes.

Physical activity of Aboriginal people in CanadaThis article is part of a supplement entitled Advancing physical activity measurement and guidelines in Canada: a scientific review and evidence-based foundation for the future of Canadian physical activity guidelines co-published by Applied Physiology, Nutrition, and Metabolism and the Canadian Journal of Public Health. It may be cited as Appl. Physiol. Nutr. Metab. 32(Suppl. 2E) or as Can. J. Public Health 98(Suppl. 2)

This paper summarizes available information on patterns of physical activity, their determinants and consequences, and the results of various interventions designed to increase the physical activity of Aboriginal peoples in Canada and the United States. There is a paucity of national data on this issue for Aboriginal peoples. The most recent data, from the First Nations Regional Longitudinal Health Survey of 2002–2003, indicate that 21% of adults (27% of men, 15% of women) were engaging in at least 30 min of moderate to vigorous physical activity on 4 d/week or more. The present paper highlights the unique challenges this group faces, underlining the need to integrate collective knowledge regarding how much physical activity is required for Aboriginal Canadians, and how this activity should be accomplished, to promote and maintain health. Efforts are currently underway to tailor Canada’s physical activity guide for First Nations, Inuit, and Métis. Future research among Aboriginal groups should examine the minimal and optimal levels of physical activity required to achieve health benefits.

Response of lipoprotein(a) levels to therapeutic life-style change in obese African-Americans

Lipoprotein(a) (Lp(a)) is regarded as an independent risk factor for Atherosclerotic cardiovascular disease. The objectives of this study were: to determine the effects of diet and exercise on Lp(a) and to evaluate the relation of Lp(a) with the lipid profile (total serum cholesterol (TC), triglycerides (TG), low density lipoprotein (LDL) and high density lipoprotein (HDL) cholesterol). Baseline Lp(a), body mass index (BMI) and the lipid profiles were measured in 343 Obese (BMI >30kg/m(2)) African-Americans. After a 3-month intervention of diet and exercise by 105 participants, their lipids were re-measured. Baseline Lp(a) levels ranged from 1.2 to 280mg/dl. Lp(a) was inversely associated with triglyceride (P<0.05). After the intervention, Lp(a) and HDL increased by a mean of 20 and 5%, respectively. Total cholesterol, triglycerides, LDL and BMI decreased by 7, 10, 11 and 8%, respectively. Women taking estrogen replacement had a negligible change in Lp(a) while participants taking HMG-CoA reductase inhibitors had an increase in Lp(a) levels by 30%.

Niacin as a component of combination therapy for dyslipidemia

Dyslipidemia is one of the most important modifiable risk factors for coronary disease. Despite the availability of highly effective lipid-modifying agents, many patients still do not reach lipid targets established by national guidelines. Niacin has been known to be an effective treatment of dyslipidemia for almost half a century. Niacin substantially increases high-density lipoprotein cholesterol (HDL-C) levels while lowering levels of low-density lipoprotein cholesterol (LDL-C), triglycerides, and lipoprotein(a). In addition, niacin converts small LDL particles into more buoyant, less atherogenic LDL particles. Combined with other agents, niacin offers an important treatment option for patients with dyslipidemia. In particular, niacin complements LDL-C-lowering drugs; it is the most effective agent available for increasing HDL-C levels while lowering levels of LDL-C and triglycerides and improving other lipid risk factors such as lipoprotein(a). Combining niacin with statins or bile acid sequestrant therapy is safe and effective for improving lipid levels and decreasing coronary risk. Differences in niacin formulations dictate tolerability profiles and should be considered when selecting niacin as part of lipid therapy. Furthermore, adverse effects on glucose and insulin sensitivity should be considered when selecting candidates for niacin therapy. Adding niacin to lipid-lowering regimens is a valuable option for physicians treating patients with dyslipidemia and should be considered in appropriate patients.

Lipids, lipoproteins, and exercise

PURPOSE

Dose-response relationships between exercise training volume and blood lipid changes suggest that exercise can favorably alter blood lipids at low training volumes, although the effects may not be observable until certain exercise thresholds are met.

METHODS AND RESULTS

Plasma triglyceride reductions are often observed after exercise training regimens requiring energy expenditures similar to those characterized to increase high-density lipoprotein cholesterol (HDL-C). Thresholds established from cross-sectional and longitudinal exercise training studies indicate that 15 to 20 miles/week of brisk walking or jogging, which elicit between 1,200 to 2,200 kcals of energy expenditure per week, is associated with triglyceride reductions of 5 to 38 mg/dL and HDL-C increases of 2 to 8 mg/dL. Exercise training seldom alters total cholesterol and low-density lipoprotein cholesterol (LDL-C) unless dietary fat intake is reduced and body weight loss is associated with the exercise training program, or both. Thus, for most individuals, the positive effects of regular exercise are exerted on blood lipids at low training volumes and accrue so that noticeable differences frequently occur with energy expenditures of 1,200 to 2,200 kcals/week.

CONCLUSIONS

It appears that weekly exercise caloric expenditures that meet or exceed the higher end of this range are more likely to produce the desired lipid changes. Regarding hyperlipidemic disorders, the primary means for intervention is pharmacologic, whereas diet modification, weight loss, and exercise, although important, are viewed as adjunctive therapies. Because much is known about the exercise training-induced plasma lipid and lipoprotein modifications as well as the mechanisms responsible for these changes, rehabilitation professionals can better develop a comprehensive medical management plan that optimizes pharmacologic, reduced dietary fat intake, weight loss, and exercise interventions.

Cardiorespiratory fitness and C-reactive protein among a tri-ethnic sample of women

BACKGROUND

Elevated C-reactive protein (CRP) is associated with increased coronary heart disease (CHD) risk. Cardiorespiratory fitness ("fitness") is related with lower CHD risk; however, its relationship with CRP is relatively unknown.

METHODS AND RESULTS

Cross-sectional associations between fitness and plasma CRP were examined among 135 African American (AA), Native American (NA), and Caucasian (CA) women (55+/-11 year; 28+/-6 kg/m2). Fitness was assessed with a maximal treadmill exercise test. Plasma CRP concentrations were determined with the Dade Behring high-sensitivity immunoassay. Geometric mean CRP levels were 0.43, 0.25, and 0.23 mg/dL, and average maximal MET levels of fitness were 7.2, 9.1, and 10 METs for AA, NA, and CA, respectively. CRP decreased across tertiles of fitness (P=0.002), increased across tertiles of BMI (P=0.0007), and varied by race (P=0.002). After adjustment for covariates, lower CRP (P<0.05) was observed across tertiles of fitness among NA and CA, but not AA. Among all women, after adjusting for race and covariates, the odds of high-risk CRP (>0.19 mg/dL) were 0.67 (95% CI=0.19 to 2.4) among fit (>6.5 METs) versus unfit women.

CONCLUSIONS

The health benefits from enhanced fitness may have an antiinflammatory mechanism.

Exercise in the treatment of lipid disorders

As a result of scientific evaluation, we know that exercise has a positive impact on the lipid and lipoprotein profile, and we have a greater understanding for the necessary amount of exercise needed to cause these changes. In the case of hyperlipidemic disorders, we know the primary means for intervention is pharmacological, and that diet, weight loss, and exercise are viewed as adjunctive therapies. Because much is known about the exercise training-induced plasma lipid and lipoprotein modifications as well as the lipoprotein enzyme changes, future research should continue to focus on the molecular basis for these changes. For example by knowing a person's apo E genotype, we gain better comprehension as to why some individuals respond to exercise, while others do not. Another area for further investigation is the assessment of drug and exercise interaction. Presently, little is known regarding the use of lipid-lowering drugs and the impact of exercise. Finally, these investigations could provide new insights for better understanding the exercise CAD protective effects. The future challenge is to better understand the impact that regular exercise participation has in optimizing the lipid and lipoprotein profile with individuals with special lipid disorders.