Modulation of lipoprotein(a) atherogenicity by high density lipoprotein cholesterol levels in middle-aged men with symptomatic coronary artery disease and normal to moderately elevated serum cholesterol. Regression Growth Evaluation Statin Study (REGRESS) Study Group

Statin therapy and lipoprotein(a) levels: a systematic review and meta-analysis

AIMS 

Lipoprotein(a) [Lp(a)] is a causal and independent risk factor for cardiovascular disease (CVD). People with elevated Lp(a) are often prescribed statins as they also often show elevated low-density lipoprotein cholesterol (LDL-C) levels. While statins are well-established in lowering LDL-C, their effect on Lp(a) remains unclear. We evaluated the effect of statins compared to placebo on Lp(a) and the effects of different types and intensities of statin therapy on Lp(a).

METHODS AND RESULTS 

We conducted a systematic review and meta-analysis of randomized trials with a statin and placebo arm. Medline and EMBASE were searched until August 2019. Quality assessment of studies was done using Cochrane risk-of-bias tool (RoB 2). Mean difference of absolute and percentage changes of Lp(a) in the statin vs. the placebo arms were pooled using a random-effects meta-analysis. We compared effects of different types and intensities of statin therapy using subgroup- and network meta-analyses. Certainty of the evidence was determined using GRADE (Grading of Recommendations, Assessment, Development, and Evaluation). Overall, 39 studies (24 448 participants) were included. Mean differences (95% confidence interval) of absolute and percentage changes in the statin vs. the placebo arms were 1.1 mg/dL (0.5-1.6, P < 0.0001) and 0.1% (-3.6% to 4.0%, P = 0.95), respectively (moderate-certainty evidence). None of the types of statins changed Lp(a) significantly compared to placebo (very low- to high-certainty evidence), as well as intensities of statin therapy (low- to moderate-certainty evidence).

CONCLUSION 

Statin therapy does not lead to clinically important differences in Lp(a) compared to placebo in patients at risk for CVD. Our findings suggest that in these patients, statin therapy will not change Lp(a)-associated CVD risk.

Cardiovascular Risk Assessment and Therapeutic Implications in Rheumatoid Arthritis

Patients with rheumatoid arthritis (RA) suffer from a magnitude of excess cardiovascular risk. A paradoxical lipid pattern has been observed in rheumatoid arthritis patients where low levels of total cholesterol and low-density lipoprotein are associated with a higher risk of cardiovascular disease. This paper aims to break down the evidence explaining why patients with low to normal LDL, and total cholesterol have such excess cardiovascular risk. A component of the enhanced cardiovascular risk is systemic inflammation and the subsequent pro-atherogenic dyslipidemia patterns. Due to this "lipid paradox," current risk algorithms and guidelines designed for the general population may underestimate cardiovascular risk in patients with rheumatoid arthritis. The purpose of this paper is to critically evaluate some of the discrepancies and layers of cardiovascular risk in RA patients, the role RA medication may have in mitigating or increasing cardiovascular risk, and the possible role of statin therapy.

Are non-high-density lipoprotein fractions associated with pediatric metabolic syndrome? The CASPIAN-V study

BACKGROUND

Non-high-density lipoprotein cholesterol (non-HDL-C) is considered as a valuable predictor for dyslipidemia and subclinical atherosclerosis which can be an appropriate index for identifying individuals with metabolic syndrome (MetS).

OBJECTIVE

To evaluate the association between non-HDL-C MetS and determine the optimal cut-points of non-HDL-C fractions for identifying MetS in Iranian children and adolescents.

METHODS

This nationwide study was conducted in the framework of the fifth survey of a national school-based surveillance program on children and adolescents aged 7-18 years. MetS was defined by the Adult Treatment Panel III (ATP III) criteria modified for the pediatric age group. The analysis of receiver operating characteristic (ROC) curve was applied to determine the optimal cut-points of non-HDL-C, difference between non-HDL-C and LDL-C (Diff-C) and triglycerides (TG) to HDL-C ratio (TG/HDL-C) for the prediction of MetS.

RESULTS

Overall, the study participants consisted of 3843 students (52.3% boys) with mean (±SD) age of 12.28 (3.1) years. The odds of high LDL-C, low HDL-C and MetS were increased in subjects with higher non-HDL-C, Diff-C and TG/HDL-C (P < 0.05). Non-HDL-C, Diff-C and TG/HDL-C cut-off points for predicting MetS were 120.5 mg/dl (sensitivity: 44%, specificity: 73%), 19.9 mg/dl (sensitivity: 85%, specificity: 75%) and 2.53 (sensitivity: 82%, specificity: 79%), respectively.

CONCLUSIONS

This study revealed a strong association between surrogates for serum lipid profile including non-HDL-C, TG/HDL-C and Diff-C and pediatric MetS. Our findings suggest that age- and gender-specific reference values of these markers were appropriate for both risk classification and long-term control of cardiovascular events in clinical assessments.

Paraoxonase-1 is a better indicator than HDL of Atherosclerosis - A pilot study in North Indian population

OBJECTIVES

The present study aims to evaluate the levels of HDL and Paraoxonase-1 (PON1) and their correlation in atherosclerotic patients with and without diabetic mellitus (DM) as well as in control subjects in Northern Indian population.

MATERIALS AND METHODS

We analyzed lipid profiles and Serum PON1 levels by automated analyzer and ELISA, respectively. Study subjects (N = 150) were divided in three groups; Group I: Atherosclerotic patients without DM (N = 50), Group II: Atherosclerotic patients with DM (N = 50); Group III: Controls (N = 50).

RESULTS

We found a significantly (p < 0.0001) low levels of HDL-C in Group I (32.2 ± 7.3) and Group II (36.9 ± 11.5) as compared to Group III (41.0 ± 7.1). PON-1 levels were also significantly lower in Group I (60.1 ± 10.5) and Group II (50.0 ± 13.9) when compared to Group III (95.0 ± 12.0). We observed a significant correlation (r = 0.59, p < 0.001) between the levels of PON1 and HDL-C in study subjects.

CONCLUSIONS

The reduced levels of HDL and PON-1 and their significant correlation in CAD patients may be associated with the pathogenesis of this disease. Considering HDL as a dependent variable, Paraoxonase-1 is the most important parameter contributing to the total variation in HDL in CAD.

Non-high-density lipoprotein fractions are strongly associated with the presence of metabolic syndrome independent of obesity and diabetes: a population-based study among Iranian adults

BACKGROUND

Non-HDL-C as a valuable predictor of premature atherosclerosis, coronary events like first Myocardial infarction and cardiovascular mortality has a high accuracy of measurement both in fasting and non-fasting individuals. Metabolic syndrome (MetS) can promote the development of diabetes mellitus, endothelial dysfunction and atherosclerosis. A common pathway for cross linking of metabolic abnormalities and non-HDL-C has been suggested. In this study we aimed to describe the potential association between non-HDL cholesterol fractions and metabolic syndrome.

METHODS

Data of third national surveillance of the risk factors of non-communicable diseases (SuRFNCD-2007) were analyzed. We defined metabolic syndrome (MetS) according to the Adult Treatment Panel III (ATPIII) and International Diabetes Federation (IDF) criteria for 2125 subjects aging 25-64 years. The receiver operating characteristic (ROC) curves were used to determine the optimal cut-points for the diagnosis of MetS. The curves were depicted for non-high-density lipoprotein cholesterol (non-HDL-C) and difference of total non-HDL-C and LDL-C (Differential cholesterol or Diff-C) as predictors of MetS. Logistic regression was also performed in a complex sample analysis scheme.

RESULTS

The area under the curve (AUC) with 95% Confidence intervals of total non-HDL-C was computed. Values were 0.693 (0.670-0.715) for IDF-defined MetS and 0.719 (0.697-0.740) for ATPIII criteria. The optimal non-HDL-C cut-point we recommend for both criteria is 153.50 mg/dl (sensitivity: 75.7%, specificity: 57.2%, with ATPIII; sensitivity: 73.2%, specificity: 57.1%, with IDF). Using IDF criteria, the accuracy of predictors were greater in non-diabetic subjects. AUC of Diff-C in DM (-) vs. DM (+) were 0.786 (0.765-0.807) vs. 0.627(0.549-0.705). Adults with high non-HDL-C were 4.42 times more likely to have ATPIII-defined MetS (≥190 vs. < 190 mg/dL). Elevated Diff-C corresponded to increased risk of the MetS (ORs: 10.71 and 26.29 for IDF and ATP III criteria, respectively. All P-values <0.001).

CONCLUSIONS

A significant robust association exists between non-HDL-C and MetS whether applying conventional or new thresholds.

Genome-wide study for circulating metabolites identifies 62 loci and reveals novel systemic effects of LPA

Genome-wide association studies have identified numerous loci linked with complex diseases, for which the molecular mechanisms remain largely unclear. Comprehensive molecular profiling of circulating metabolites captures highly heritable traits, which can help to uncover metabolic pathophysiology underlying established disease variants. We conduct an extended genome-wide association study of genetic influences on 123 circulating metabolic traits quantified by nuclear magnetic resonance metabolomics from up to 24,925 individuals and identify eight novel loci for amino acids, pyruvate and fatty acids. The LPA locus link with cardiovascular risk exemplifies how detailed metabolic profiling may inform underlying aetiology via extensive associations with very-low-density lipoprotein and triglyceride metabolism. Genetic fine mapping and Mendelian randomization uncover wide-spread causal effects of lipoprotein(a) on overall lipoprotein metabolism and we assess potential pleiotropic consequences of genetically elevated lipoprotein(a) on diverse morbidities via electronic health-care records. Our findings strengthen the argument for safe LPA-targeted intervention to reduce cardiovascular risk.

Circulating metabolites reflect human health and disease. Here, Kettunen et al. perform a genome-wide association study on 123 circulating metabolic traits and identify novel genetic loci influencing systemic metabolism. They also link new molecular pathways with a known cardiovascular risk factor Lp(a).

South Asian Ethnicity and Cardiovascular Risk

South Asians (SAs), in their countries or after migration, are at high risk of coronary artery disease (CAD) and mortality compared to other ethnic groups. It has been shown that >90% of CAD global risk could be attributed to 9 modifiable risk factors (RFs) worldwide. However, these conventional RFs may not fully explain this high risk of CAD among SAs. Therefore, attention has been directed toward nonconventional RFs. In this narrative review, we evaluate the conventional and emerging cardiovascular RFs characterizing SAs. These factors may explain the high morbidity and mortality among SAs. Further prospective studies are urgently needed to set algorithms for the optimal management of these RFs in high-risk populations like SAs.

Lipoprotein(a) and cardiovascular disease in diabetic patients

Lipoprotein(a) (Lp[a]) is a LDL-like particle consisting of an ApoA moiety linked to one molecule of ApoB(100). Recent data from large-scale prospective studies and genetic association studies provide highly suggestive evidence for a potentially causal role of Lp(a) in affecting risk of cardiovascular disease (CVD) in general populations. Patients with Type 2 diabetes display clustered metabolic abnormalities and elevated risk of CVD. Lower plasma Lp(a) levels were observed in diabetic patients in several recent studies. Epidemiology studies of Lp(a) and CVD risk in diabetic patients generated inconsistent results. We recently found that Lp(a)-related genetic markers did not predict CVD in two diabetic cohorts. The current data suggest that Lp(a) may differentially affect cardiovascular risk in diabetic patients and in the general population. More prospective studies, Mendelian randomization analysis and functional studies are needed to clarify the causal relationship of Lp(a) and CVD in diabetic patients.

Lipoprotein(a): more interesting than ever after 50 years

PURPOSE OF REVIEW

Lipoprotein(a) [Lp(a)] is a risk factor for cardiovascular disease; we highlight the most recent research initiatives that have sought to define Lp(a)-dependent pathogenicity as well as pharmacologic approaches to lowering Lp(a).

RECENT FINDINGS

Recent large-scale meta-analyses have confirmed elevated Lp(a) concentrations to be a moderate but consistent prospective coronary heart disease (CHD) risk factor. The Mendelian randomization approach has also associated LPA variants with Lp(a) concentration and CHD risk. Discoveries linking Lp(a) to oxidized phospholipid burden have implicated a proinflammatory role for Lp(a) hinting at a new mechanism underlying the association with CHD risk, which adds to previous atherogenic and thrombogenic mechanisms. Most existing Lp(a)-lowering drug treatments almost always show simultaneous effects on other lipoproteins, making it difficult to assign any clinical outcome specifically to the effects of Lp(a) lowering. Early experiments with antisense oligonucleotides targeting apolipoprotein(a) mRNA seem to indicate the pleiotropic effects of Lp(a) reduction on LDL and HDL in mice. The mechanism linking Lp(a) concentration with concentrations of other blood lipids remains unknown but may provide an insight into Lp(a) metabolism.

SUMMARY

Despite the wealth of epidemiologic evidence supporting Lp(a) concentration as a CHD risk factor, the lack of a definitive functional mechanism involving an Lp(a)-dependent pathway in CHD pathogenesis has limited the potential clinical connotation of Lp(a). However, the application of novel technologies to the long-standing mysteries of Lp(a) biology seems to provide the opportunity for expanding our understanding of Lp(a) and its complex role in cardiovascular health.

Lipid and low-density-lipoprotein apheresis. Effects on plasma inflammatory profile and on cytokine pattern in patients with severe dyslipidemia

Available evidence on the effects of therapeutic plasmapheresis (TP) techniques and in particular lipid- and LDL-apheresis (LDL-a) on plasmatic inflammatory mediators including cytokines were reviewed. Studies on this issue are not numerous. However, the review of existing evidence clearly suggests an active role of apheresis on the profile of inflammatory molecules and on cytokine pattern in plasma. These non-lipid-lowering effects can be defined to some extent pleiotropic or pleiotropic-equivalent. Although further studies are desirable, the data reported in this review confirm that lipid- and LDL-a not only show acute lipid-lowering and cholesterol-lowering effects, but also efficacy in reducing several proinflammatory peptides, including cytokines. This effect was not related apparently to lipids and lipoproteins reduction. Thus, TP (lipid- and LDL-a), commonly utilized in the treatment of severe genetically determined lipid disorders, unresponsive to hypolipidemic drugs, offers new possibilities of interpretation of its role in the mechanisms leading to the blockade of atherosclerotic lesion development and progression. The ability of TP on short-term to induce such a profound change in the plasmatic metabolic and inflammatory profiles must be kept in mind in the treatment of acute coronary syndromes, before and after interventions of coronary revascularization, and in the acute phase of cerebrovascular ischemia, at least in patients with severe dyslipidemia. Further studies are needed, in particular aimed at assessing if circulating cytokines may be downregulated by TP not only by direct removal, but through indirect effects on both gene translation and transcription perhaps via the cytokine receptor function.

Discovery and validation of new molecular targets in treating dyslipidemia: the role of human genetics

Several high-profile failures of lipid-related therapeutics in clinical trials have led to intense interest in improved discovery and preclinical prioritization of potential targets. The careful study of patients with rare monogenic disorders has played a key role in establishing the causal role of cholesterol in atherosclerosis and highlighting viable drug targets. Systematic efforts to extend the association of common variants linked with lipid levels to coronary disease enable assessment of the vascular consequences of lifelong differences in lipids due to variation in specific molecules. This application of genetic epidemiology, termed Mendelian randomization, may prove useful in informing ongoing drug development efforts.

Lp(a) and risk of recurrent cardiac events in obese postinfarction patients

Studies of recurrent coronary events in obese postinfarction patients show mixed results despite potential importance of obesity-related pathophysiologic processes and associated markers in establishing and predicting risk. The study aim was to determine specific markers of recurrent risk in obese postinfarction patients. Nondiabetic patients of the Thrombogenic Factors and Recurrent Coronary Events (THROMBO) postinfarction study were classified according to BMI as normal weight (<25 kg/m(2)), overweight (25.0-29.9 kg/m(2)), and obese (> or = 30 kg/m(2)). Cox multivariable regression with adjustment for significant clinical covariates was performed in each group monitoring outcome (cardiac death, myocardial infarction (MI), or unstable angina with 26 months follow-up) as a function of 17 thrombogenic, inflammatory, and metabolic blood markers and 17 cardiovascular disease-associated genetic polymorphisms. Results revealed no statistically significant genetic or blood marker variables in normal or overweight patients. For obese postinfarction patients, elevated lipoprotein(a) (Lp(a))was found to be a highly significant risk marker with hazard ratio and 95% confidence interval of 3.94 (2.11-7.35), P = 0.000017 (upper tertile vs. lower two tertiles). Additionally, elevated Lp(a) was found to interact with the -75G>A polymorphism of the apolipoprotein A-I gene and the -250G>A polymorphism of the hepatic lipase gene in establishing risk. We conclude that interactions of elevated Lp(a) with polymorphisms of the apolipoprotein A-I and hepatic lipase genes, primarily reflective of altered lipoprotein metabolism, play an important role in the establishment of recurrent coronary event risk in obese, nondiabetic postinfarction patients. These findings suggest close monitoring and consideration of weight reduction for obese postinfarction patients with elevated Lp(a) levels.

Asymmetric development of peripheral atherosclerosis in patients with erectile dysfunction: An ultrasonographic study

Recent literature focused on erectile dysfunction (ED) as a reliable predictive parameter of cardiovascular diseases. ED patients have a higher prevalence of atherosclerotic lesions (increased intima-media thickness and plaques) at carotid site, but data on femoral site are still lacking. Nevertheless, there is accumulating evidence concerning a significant involvement of femoral atherosclerosis in other clinical conditions associated to ED, such as diabetes mellitus and coronary disease. Therefore, we investigated the prevalence of carotid and femoral atherosclerotic lesions and penile peak systolic velocity (PSV) in 238 ED patients by Eco-Colour Doppler ultrasonography (US). We found - irrespective of the presence of cardiovascular risk factors - a significant increase of atherosclerotic lesions in ED group with respect to 52 controls (66.4% versus 36.5%) and a higher prevalence of atherosclerosis at the femoral site (23.1% versus 5.7%), also with respect to the carotid site (8%). Moreover, PSV was significantly lower in ED patients with atherosclerosis compared to those without atherosclerotic lesions (41.9+/-15.3 cm/s versus 55.2+/-17.7 cm/s), and it was particularly low in those with combined carotid and femoral atherosclerosis (34.8+/-13.3 cm/s) and those with isolated carotid atherosclerosis (37.9+/-13.0 cm/s). These data confirm the strong relation between atherosclerosis and ED, an asymmetric development of atherosclerotic lesions in ED patients and suggest to perform an US study of both femoral and carotid district in these subjects.

The Role of Statin Drugs in the Management of the Peripheral Vascular Patient

The impact of statin therapy on established vascular conditions and recurrent disease is most relevant for long-term care. Patients receiving statin therapy have been shown to experience less recurrent stenosis following carotid endarterectomy and stent angioplasty, reduced cardiac events following cardiac and noncardiac vascular surgery, and reduction in aneurysm development. In patients with peripheral arterial disease, claudication distance is increased, as well as patency rates following infrainguinal arterial bypass grafting. Of note, statins drugs may also prove beneficial in the prevention of certain cancers, Alzheimer's disease, and osteoporosis (all diseases frequently seen concurrently in the patient with peripheral arterial disease). As such, it is becoming all the more necessary that vascular surgeons remain informed about clinical research initiatives related to statin use and lipid management in general. The following is a review of lipid metabolism as it applies to statins as well as a review of the beneficial effects of statins.

High-density lipoprotein subclass distribution in individuals of Asian Indian descent: the National Asian Indian Heart Disease Project

Individuals of Asian Indian descent have significantly higher cardiovascular event rates as compared with other ethnic groups. The authors investigated the prevalence of metabolic disorders linked to coronary artery disease in an Asian Indian male population compared with non-Asian Indian males. Standard lipid measurements did not discriminate between groups, and the Asian Indian group exhibited less of the high coronary artery disease risk small low-density lipoprotein trait. Despite less of the small low-density lipoprotein trait in the Asian Indian group and no difference in high-density lipoprotein cholesterol, the Asian Indian group had a significantly higher prevalence (p < 0.0002) of low high-density lipoprotein 2b, implying impaired reverse cholesterol transport. This observation remained significant in the subgroup of patients with high-density lipoprotein cholesterol over 40 mg/dL, a region felt not to reflect impaired reverse cholesterol transport. Low high-density lipoprotein 2b combined with the higher lipoprotein(a) in the Asian Indian group may help explain the high prevalence of coronary artery disease in this ethnic population.

Structural features of apolipoprotein B synthetic peptides that inhibit lipoprotein(a) assembly

Lipoprotein(a) [Lp(a)] is assembled via an initial noncovalent interaction between apolipoprotein B100 (apoB) and apolipoprotein(a) [apo(a)] that facilitates the formation of a disulfide bond between the two proteins. We previously reported that a lysine-rich, alpha-helical peptide spanning human apoB amino acids 4372-4392 was an effective inhibitor of Lp(a) assembly in vitro. To identify the important structural features required for inhibitory action, new variants of the apoB4372-4392 peptide were investigated. Introduction of a central leucine to proline substitution abolished the alpha-helical structure of the peptide and disrupted apo(a) binding and inhibition of Lp(a) formation. Substitution of hydrophobic residues in the apoB4372-4392 peptide disrupted apo(a) binding and inhibition of Lp(a) assembly without disrupting the alpha-helical structure. Substitution of all four lysine residues in the peptide with arginine decreased the IC50 from 40 microM to 5 microM . Complexing of the arginine-substituted peptide to dimyristoylphosphatidylcholine improved its activity further, yielding an IC50 of 1 microM. We conclude that the alpha-helical structure of apoB4372-4392, in combination with hydrophobic residues at the lipid/water interface, is crucial for its interaction with apo(a). Furthermore, the interaction of apoB4372-4392 with apo(a) is not lysine specific, because substitutions with arginine result in a more effective inhibitor.

Report of the National Heart, Lung, and Blood Institute Workshop on Lipoprotein(a) and Cardiovascular Disease: Recent Advances and Future Directions

It has been estimated that ∼37% of the US population judged to be at high risk for developing coronary artery disease (CAD), based on the National Cholesterol Education Program guidelines, have increased plasma lipoprotein(a) [Lp(a)], whereas Lp(a) is increased in only 14% of those judged to be at low risk. Therefore, the importance of establishing a better understanding of the relative contribution of Lp(a) to the risk burden for CAD and other forms of vascular disease, as well as the underlying mechanisms, is clearly evident. However, the structural complexity and size heterogeneity of Lp(a) have hindered the development of immunoassays to accurately measure Lp(a) concentrations in plasma. The large intermethod variation in Lp(a) values has made it difficult to compare data from different clinical studies and to achieve a uniform interpretation of clinical data. A workshop was recently convened by the National Heart, Lung, and Blood Institute (NHLBI) to evaluate our current understanding of Lp(a) as a risk factor for atherosclerotic disorders; to determine how future studies could be designed to more clearly define the extent to which, and mechanisms by which, Lp(a) participates in these processes; and to present the results of the NHLBI-supported program for the evaluation and standardization of Lp(a) immunoassays. This report includes the most recent data presented by the workshop participants and the resulting practical and research recommendations.

Predictors of adverse long-term outcome in acute myocardial infarction patients undergoing primary percutaneous transluminal coronary angioplasty: with special reference to the admission concentration of lipoprotein (a)

The predictive values for long-term outcome in 127 consecutive patients with acute myocardial infarction (AMI) after successful primary percutaneous transluminal coronary angioplasty (PTCA) were prospectively investigated in the present study. The primary endpoint was a composite of cardiac death, nonfatal AMI, and recurrent angina. Follow-up angiography was performed in 120 patients to assess restenosis. The primary endpoint occurred in 21 patients during a follow-up period of 35+/-24 months. These patients had a higher lipoprotein(a) [Lp(a)] concentration (p=0.0105) and more prevalence of multivessel disease (p=0.0028) than the other patients. The subjects were divided into 2 groups at the 75th percentile Lp(a) value: group A had an Lp(a) concentration >or=47 mg/dl and group B <47 mg/dl. Kaplan-Meier analysis showed a lower cardiac event-free survival rate in group A (p=0.0007) and in patients with multivessel disease (p=0.001). In Cox proportional hazards regression analysis, an Lp(a) level >or=47 mg/dl (relative risk[RR] 5.5, 95% confidence interval [CI] 2.0-15.0, p=0.0007) and multivessel disease (RR 5.3, 95% CI 2.0-13.7, p=0.0006) were independent predictors of the primary endpoint. An elevated Lp(a) concentration on admission and multivessel disease are significant predictors for long-term adverse outcome in AMI patients treated by primary PTCA.

The combination of nebivolol plus pravastatin is associated with a more beneficial metabolic profile compared to that of atenolol plus pravastatin in hypertensive patients with dyslipidemia: a pilot study

Nebivolol, a selective beta1-lipophilic blocker, achieves blood pressure control by modulating nitric oxide release in addition to b-blockade. This dual mechanism of action could result in minimum interference with lipid metabolism compared to atenolol, a classic beta1-selective blocker. Hypertensive patients commonly exhibit lipid abnormalities and frequently require statins in combination with the anti-hypertensive therapy. We conducted this trial in order to clarify the effect on the metabolic profile of beta-blocker therapy with atenolol or nebivolol alone, or in conjunction with pravastatin. Thirty hypertensive hyperlipidemic men and women (total cholesterol >240 mg/dL [6.2 mmol/L], low-density lipoprotein cholesterol >190 mg/dL [4.9 mmol/L], triglycerides <500 mg/dL [5.6 mmol/L]) were separated in two groups. One group consisted of 15 subjects on atenolol therapy (50 mg daily), and the other group included 15 subjects on nebivolol therapy (5 mg daily). After 12 weeks of beta-blocker therapy, pravastatin (40 mg daily) was added in both groups for another 12 weeks. Atenolol significantly increased triglyceride levels by 19% (P=.05), while nebivolol showed a trend to increase high-density lipoprotein cholesterol by 8% (NS) and to decrease triglyceride levels by 5% (NS). Atenolol significantly increased lipoprotein(a) by 30% (P=.028). Fibrinogen levels were equally and not significantly decreased in both groups by 9% and 7%, respectively. Furthermore, atenolol and nebivolol decreased serum high-sensitivity C-reactive protein levels by 14% (P=.05) and 15% (P=.05), respectively. On the other hand, both atenolol and nebivolol showed a trend to increase homocysteine levels (NS) by 13% and 11%, respectively. Although uric acid levels remained the same, atenolol significantly increased the fractional excretion of uric acid by 33% (P=.03). Following nebivolol administration, glucose levels remained the same, while insulin levels were reduced by 10% and the HOMA index (fasting glucose levels multiplied by fasting insulin levels and divided by 22.5) was reduced by 20% (P=.05). There were no significant differences between the two patient groups in the measured parameters after the administration of beta-blockers, except for triglycerides (P<.05) and the HOMA index (P=.05). The addition of pravastatin to all patients (n=30) decreased total cholesterol by 21% (P<.001), low-density lipoprotein cholesterol by 28% (P<.001), apolipoprotein-B by 22% (P<.001), apolipoprotein-E by 15% (P=.014) and lipoprotein(a) levels by 12% (P=.023). Moreover, homocysteine levels and C-reactive protein were reduced by 17% (P=.05) and 43% (P=.05), respectively. We conclude that nebivolol seems to be a more appropriate therapy in hypertensive patients with hyperlipidemia and carbohydrate intolerance. Finally, the addition of pravastatin could further correct the well-established predictors of cardiovascular events.

Smallest LDL particles are most strongly related to coronary disease progression in men

OBJECTIVE

LDLs include particle subclasses that have different mobilities on polyacrylamide gradient gels: LDL-I (27.2 to 28.5 nm), LDL-IIa (26.5 to 27.2 nm), LDL-IIb (25.6 to 26.5 nm), LDL-IIIa (24.7 to 25.6 nm), LDL-IIIb (24.2 to 24.7 nm), LDL-IVa (23.3 to 24.2 nm), and LDL-IVb (22.0 to 23.3 nm in diameter). We hypothesized that the association between smaller LDL particles and coronary artery disease (CAD) risk might involve specific LDL subclasses.

METHODS AND RESULTS

Average 4-year onstudy lipoprotein measurements were compared with annualized rates of stenosis change from baseline to 4 years in 117 men with CAD. The percentages of total LDL and HDL occurring within individual subclasses were measured by gradient gel electrophoresis. Annual rate of stenosis change was related concordantly to onstudy averages of total cholesterol (P=0.04), triglycerides (P=0.05), VLDL mass (P=0.03), total/HDL cholesterol ratio (P=0.04), LDL-IVb (P=0.01), and HDL(3a) (P=0.02) and inversely to HDL(2)-mass (P=0.02) and HDL(2b) (P=0.03). The average annual rate in stenosis change was 6-fold more rapid in the fourth quartile of LDL-IVb (>or=5.2%) than in the first quartile (<2.5%, P=0.03). Stepwise multiple regression analysis showed that LDL-IVb was the single best predictor of stenosis change.

CONCLUSIONS

LDL-IVb was the single best lipoprotein predictor of increased stenosis, an unexpected result, given that LDL-IVb represents only a minor fraction of total LDL.

Lipoprotein abnormalities in hemodialysis and continuous ambulatory peritoneal dialysis patients

Lipid abnormalities are important variables in the development of vascular atherosclerotic lesions in ESRD patients while Lp(a) represents an independent risk factor. In order to evaluate lipid changes in HD and CAPD patients, serum cholesterol (TC), HDLc, LDLc, TG, apolipoproteins (AI,AII,B,E), Lp(a), and albumin levels were estimated in 109 ESRD dialyzed patients, 46 in HD and 63 in CAPD (mean duration 50 +/- 40 and 25 +/- 19 months, respectively), and 45 volunteers with high serum levels of C and TG, without renal insufficiency. Both HD and PD group revealed statistically significantly higher levels than controls for TC, TG, LDL-C, Apo-B,-E, while HDL-C levels were significantly lower. Except for the lower serum albumin levels in both dialyzed groups after six months lower ApoAI levels and higher ApoB levels were observed in HD and PD patients respectively. Lp(a) levels remained unchanged in HD group, while a statistically significant increase appeared in PD patients that was negative correlated with the decreased serum albumin levels. These results indicate that renal replacement modalities result in a different effect in lipoprotein metabolism that may play an important role in atherosclerotic vascular disease of dialyzed ESRD patients.

Lipids and risk assessment

Because a standard lipid panel can misrepresent lipoprotein abnormalities that contribute to atherosclerosis, more detailed laboratory analysis should be considered in a patient whose level of risk is unclear. This is especially important for patients who have a family history of premature coronary heart disease of uncertain etiology. Such testing is analogous to performing a more advanced imaging procedure when a plain x-ray lacks the sensitivity to define an anatomic derangement. In selected situations, measuring apolipoprotein B, lipoprotein (a), low-density lipoprotein, or high-density lipoprotein subfractions, or homocysteine can markedly clarify cardiovascular risk. This review describes seven men, themselves cardiologists, who had misinterpreted their own risk based on conventional lipid tests. With further evaluation, one of these men was reassured that he had lower risk than he had feared. Six of the men had greater risk than previously recognized.

Triglyceride and lipoprotein (a) are markers of coronary artery disease severity among postmenopausal women

OBJECTIVE

After menopause, some women manifest coronary artery disease (CAD) with highly variable angiographic severity. For these women, postmenopausal appearing of some CAD risk factors may have differently influenced the CAD risk and severity. In this study, we attempt to unravel differences in the frequency or intensity of CAD risk factors among postmenopausal women with different angiographic severity.

METHODS

We studied 182 postmenopausal women (64+/-6 years) who underwent coronary angiography to investigate thoracic pain. Subjects with no detectable coronary lesions at angiography were recruited to the non-obstructive group and patients with CAD were grouped in one-vessel or multi-vessel groups. We compared clinical variables as the body mass index (BMI), age at menopause, age, hypertension, diabetes and cigarette smoking, and lipid measurements as plasma levels of total cholesterol, triglyceride, low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, apolipoprotein (apo) A1, apo B and lipoprotein(a) (Lp(a)).

RESULTS

Comparing to the non-obstructive group, Lp(a) was twofold higher in the one-vessel group and threefold higher in the multi-vessel group and triglycerides were 34% higher in the one-vessel group and 50% higher in the multi-vessel group. No further difference was found among the three groups. After multivariate logistic regression analysis, triglyceride (odds ratio: 1.01; P=0.0013) and Lp(a) (odds ratio: 1.006; P<0.0001) were independently indicative of the presence of obstructive CAD.

CONCLUSIONS

We found that both Lp(a) and triglycerides constitute useful markers of CAD severity among postmenopausal women.

Risk factors that discriminate 'high- risk' from 'low-risk' Japanese patients with coronary artery disease

Although various risk factors have been implicated in the progression of coronary artery disease (CAD), coronary risk factors specifically related to the long-term prognosis for high-risk CAD have not been determined. The study enrolled 311 consecutive Japanese patients with CAD who underwent diagnostic coronary arteriography and divided them into 2 groups: (i) 135 high-risk patients with either impaired left ventricular function (ejection fraction <50%) or multivessel disease and (ii) 176 low-risk patients with normal left ventricular function and 0- or 1-vessel disease. The prevalence of risk factors including age, gender, smoking, hypertension, diabetes mellitus (DM), obesity and lipid variables were compared between the 2 groups. The prevalence of DM, a serum high-density lipoprotein (HDL)-cholesterol level below 35 mg/dl and a serum lipoprotein (Lp) (a) level above 25 mg/dl was significantly higher in the high-risk group as compared with the low-risk group. Multiple logistic regression analysis demonstrated that DM (odds ratio (OR): 1.72, 95% confidence intervals (CI): 1.02-2.92, p<0.05), a low HDL-cholesterol level (OR: 2.49, 95% CI: 1.49-4.17, p<0.001) and a high Lp(a) level (OR: 1.68, 95% CI: 1.02-2.76, p<0.05) were all independent risk factors for high-risk CAD. However, if the patients with 0-vessel disease were excluded from the low-risk group, a low HDL-cholesterol level was found to be the only independent predictor for high-risk CAD (OR: 2.07, 95% CI: 1.15-3.70, p<0.05). Among both men and smokers in this population, a higher Lp(a) level was found to be a significant predictor for high-risk CAD. A low serum level of HDL-cholesterol, a high serum level of Lp(a) and DM were significant predictors of high-risk in patients with CAD. Among patients with a significant coronary stenosis or left ventricular dysfunction, a low serum level of HDL-cholesterol was the only significant predictor for high-risk CAD.

Lipoprotein(a) is a risk factor for occurrence of acute myocardial infarction in patients with coronary vasospasm

OBJECTIVES

The purpose of this study is to determine whether lipoprotein(a) (Lp[a]) is an independent risk factor for coronary spasm and occurrence of acute myocardial infarction (AMI) in patients with coronary spasm.

BACKGROUND

Although elevated serum Lp(a) levels are known to be associated with coronary atherosclerosis and AMI, the association between the elevated level of this lipoprotein and coronary spasm remains to be elucidated.

METHODS

Serum Lp(a) levels were measured using a latex immunoassay in 77 patients with coronary spasm but without a significant (>75%) fixed coronary stenosis, including 16 with prior myocardial infarction (MI), in 177 patients with a fixed stenosis but without rest angina, including 114 with prior MI and in 81 control subjects without coronary artery disease.

RESULTS

The serum Lp(a) level in patients with coronary spasm (median; 17 mg/dl) was higher (p < 0.01) than in control subjects (12 mg/dl) but lower (p < 0.01) than in patients with a fixed stenosis (23 mg/dl). The incidence of subjects with higher (>25 mg/dl) serum Lp(a) levels was higher in patients with a fixed stenosis (46%, p < 0.01) but not in patients with coronary spasm (27%), compared with control subjects (21%). Among the patients with coronary spasm, the incidence of higher Lp(a) levels was higher in patients with than in those without a history of prior MI (56% vs. 21%, p < 0.05). The patients with higher Lp(a) levels had a higher incidence of prior MI than those without (41% vs. 13%, p < 0.05). The multivariate analysis confirmed that higher serum Lp(a) level is an independent determinant for prior MI in these patients (odds ratio, 4.19; 95%, confidence interval, 1.03 to 17.00).

CONCLUSIONS

Elevated serum level of Lp(a) was found to be associated with a history of prior MI in patients with coronary spasm, suggesting that Lp(a) may play an important role in the genesis of thrombotic coronary occlusion and the occurrence of AMI subsequent to coronary spasm.

Lipoprotein(a), homocysteine, and remnantlike particles: emerging risk factors

Although lipoprotein(a) [Lp(a)] was first described more than 35 years ago, adequate prospective data have only recently supported Lp(a) as an independent risk factor for coronary heart disease (CHD). In vitro studies suggest that Lp(a) contributes to atherogenesis directly by cholesterol uptake and indirectly by the inhibition of fibrinolysis. In patients with CHD or a significant risk for CHD, Lp(a) should be measured and treated with either niacin or estrogen if the patient has Lp(a) cholesterol levels of more than 10 mg/dL or an Lp(a) mass of more than 30 mg/dL. In addition, homocysteine and remnantlike lipoprotein cholesterol are strongly supported by prospective or population-based prevalence data as independent risk factors for CHD. Homocysteine levels of more than 14 mumol/L should be treated with vitamin supplements of folate, B6, and B12. Remnantlike lipoprotein cholesterol is the product of a novel immunoassay that separates the partially hydrolyzed triglyceride-rich remnant particles. The association of these particles with CHD risk in women may explain the small independent CHD risk that triglycerides have in women in the Framingham Heart Study. A clear therapeutic intervention has not been documented but may include diet, fibric acid derivatives, or hydroxymethylglutamyl coenzyme A reductase inhibitors.

Lipoprotein(a) concentrations in healthy subjects in the Dominican Republic. Comparison with Japanese

Previous studies have shown that serum concentrations of lipoprotein(a) [Lp(a)] are markedly different among different ethnic groups. We examined the serum levels of total cholesterol, high density lipoprotein (HDL) cholesterol and Lp(a) in apparently healthy subjects aged 20-69 years in Japan (n = 865) and the Dominican Republic (n = 1,893). Dominicans had significantly lower levels of total cholesterol and HDL cholesterol than Japanese. The distribution of Lp(a) concentrations were markedly skewed towards low levels in both Japanese and Dominicans. However, the mean Lp(a) concentration in Dominicans was approximately 2 times higher than in Japanese (21.7 +/- 23.7 vs 12.3 +/- 15.9 mg/dl, p < 0.001). This is possibly because the majority of Dominicans are of mixed Negroid and European blood.

Effect of HMG-CoA reductase inhibitors on coronary artery disease as assessed by electron-beam computed tomography

BACKGROUND

Angiographic studies of the regression of coronary artery disease are invasive and costly, and they permit only limited assessment of changes in the extent of atherosclerotic disease. Electron-beam computed tomography (CT) is noninvasive and inexpensive. The entire coronary-artery tree can be studied during a single imaging session, and the volume of coronary calcification as quantified with this technique correlates closely with the total burden of atherosclerotic plaque.

METHODS

We conducted a retrospective study of 149 patients (61 percent men and 39 percent women; age range, 32 to 75 years) with no history of coronary artery disease who were referred by their primary care physicians for screening electron-beam CT. All patients underwent base-line scanning and follow-up assessment after a minimum of 12 months (range, 12 to 15), and a volumetric calcium score was calculated as an estimate of the total burden of plaque. Treatment with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors was begun at the discretion of the referring physician. Serial measurements of low-density lipoprotein (LDL) cholesterol were obtained, and the change in the calcium-volume score was correlated with average LDL cholesterol levels.

RESULTS

One hundred five patients (70 percent) received treatment with HMG-CoA reductase inhibitors, and 44 patients (30 percent) did not. At follow-up, a net reduction in the calcium-volume score was observed only in the 65 treated patients whose final LDL cholesterol levels were less than 120 mg per deciliter (3.10 mmol per liter) (mean [+/-SD] change in the score, -7+/-23 percent; P=0.01). Untreated patients had an average LDL cholesterol level of at least 120 mg per deciliter and at the time of follow-up had a significant net increase in mean calcium-volume score (mean change, +52+/-36 percent; P<0.001). The 40 treated patients who had average LDL cholesterol levels of at least 120 mg per deciliter had a measurable increase in mean calcium-volume score (25+/-22 percent, P<0.001), although it was smaller than the increase in the untreated patients.

CONCLUSIONS

The extent to which the volume of atherosclerotic plaque decreased, stabilized, or increased was directly related to treatment with HMG-CoA reductase inhibitors and the resulting serum LDL cholesterol levels. These changes can be determined noninvasively by electron-beam CT and quantified with use of a calcium-volume score.

Genetics of lipoprotein disorders

The study of lipoprotein metabolism has led to major breakthroughs in the fields of cellular physiology, molecular genetics, and protein chemistry. These advances in basic science are reflected in medicine in the form of improved diagnostic methods and better therapeutic tools. Perhaps the greatest benefit is the improved ability to identify at an early stage patients who are at high risk for atherosclerosis, providing clinicians the opportunity to proceed swiftly with intensive lipid-lowering therapy for the prevention of cardiovascular complications. Recent clinical trials have shown that such an approach is not only cost-effective but saves lives while improving the quality of life. They also emphasize the important role physicians can have in prevention. More than half of patients with premature CAD have a familial form of dyslipoproteinemia. This review of the genetics of atherogenic lipoprotein disorders underscores the importance of identifying major genetic defects. It also stresses the need to take into account multifactorial etiologies and clustering of risk factors, as well as gene-gene and gene-environment interactions in assessing the atherogenic potential of a lipid transport disorder. Table 2 summarizes the key points in the diagnosis, clinical implications, and treatment of the major inherited atherogenic dyslipidemias.

Lipoprotein classes and coronary disease regression

Lowering LDL cholesterol (LDL-C) levels to reduce or prevent coronary artery disease (CAD) progression and cardiac events in hypercholesterolemic subjects is now widely accepted. The clinical benefit of lowering LDL-C has recently been extended to individuals with normal or mildly elevated LDL-C. Recent analyses of large primary and secondary CAD prevention trials, however, clearly demonstrated that reducing LDL-C levels does not entirely account for the coronary event reduction associated with lipid-lowering therapy. Growing and compelling evidence is emerging on the role of triglyceride-rich lipoproteins (VLDL and IDL), high density lipoproteins (HDL), and small, dense LDL, as well as non lipid risk factors, in the regression or stabilization of atherosclerotic plaques of mild/moderate severity, which are associated with clinical cardiac events. Enzymes involved in the tight metabolic interrelationship between triglyceride-rich lipoproteins, small, dense LDL and HDL levels may represent potential therapeutic targets for CAD prevention by favourably altering lipoprotein composition and physical properties in addition to the current therapeutic focus on lipoprotein levels.