Plasma lipoprotein(a) is an independent factor associated with carotid wall thickening in severely but not moderately hypercholesterolemic patients

Gender difference in lipoprotein(a) concentration as a predictor of coronary revascularization in patients with known coronary artery disease

BACKGROUND AND AIMS

Whether there is a gender difference in the impact of elevated plasma Lp(a) levels on recurrent coronary events remains unclear. We, therefore, evaluated the association between Lp(a) levels and the occurrence of major adverse coronary events in a large series of coronary patients (32% women).

METHODS

This single-center prospective cohort study investigated 3034 consecutive patients admitted to the Coronary Care Unit with a diagnosis of coronary ischemia. According to the inclusion criteria, 2374 patients completed the follow-up (mean of 2 years). The end-points were non-fatal myocardial infarction (MI), revascularization and coronary deaths.

RESULTS

Elevated Lp(a) levels were significantly associated with rate of revascularization, but not with non-fatal MI and cardiac death. According to Lp(a) stratification (≤30 mg/dl, >30-50 mg/dl and ≥50 mg/dl), there was a significant rise of revascularization events in the whole sample of participants, with a trend in hazard ratio (HR) of 1.23 (95% CI 1.04-1.46) and a 6% rise for every 10 mg/dl increment in Lp(a) levels. This effect was mainly driven by women (HR 2.04, 95%CI 1.33-3.12) who showed a 14% incremental risk for every 10 mg/dl rise in Lp(a) levels.

CONCLUSIONS

In patients with coronary artery disease, elevated plasma Lp(a) levels were found to be a potentially useful predictor of the need for coronary revascularizations, especially in women.

Elevated Lp(a) (Lipoprotein[a]) Levels Increase Risk of 30-Day Major Adverse Cardiovascular Events in Patients Following Carotid Endarterectomy

Background and Purpose:

General population studies have shown that elevated Lp(a) (lipoprotein[a]) levels are an emerging risk factor for cardiovascular disease and subsequent cardiovascular events. The role of Lp(a) for the risk of secondary MACE in patients undergoing carotid endarterectomy (CEA) is unknown. Our objective is to assess the association of elevated Lp(a) levels with the risk of secondary MACE in patients undergoing CEA.

Methods:

Lp(a) concentrations were determined in preoperative blood samples of 944 consecutive patients with CEA included in the Athero-Express Biobank Study. During 3-year follow-up, major adverse cardiovascular events (MACE), consisting of myocardial infarction, stroke, and cardiovascular death, were documented.

Results:

After 3 years follow-up, Kaplan-Meier cumulative event rates for MACE were 15.4% in patients with high Lp(a) levels (>137 nmol/L; >80th cohort percentile) and 10.2% in patients with low Lp(a) levels (≤137 nmol/L; ≤80th cohort percentile; log-rank test: P =0.047). Cox regression analyses adjusted for conventional cardiovascular risk factors revealed a significant association between high Lp(a) levels and 3-year MACE with an adjusted hazard ratio of 1.69 (95% CI, 1.07–2.66). One-third of MACE occurred within 30 days after CEA, with an adjusted hazard ratio for the 30-day risk of MACE of 2.05 (95% CI, 1.01–4.17). Kaplan-Meier curves from time point 30 days to 3 years onward revealed no significant association between high Lp(a) levels and MACE. Lp(a) levels were not associated with histological carotid plaque characteristics.

Conclusions:

High Lp(a) levels (>137 nmol/L; >80th cohort percentile) are associated with an increased risk of 30-day MACE after CEA. This identifies elevated Lp(a) levels as a new potential risk factor for secondary cardiovascular events in patients after carotid surgery. Future studies are required to investigate whether Lp(a) levels might be useful in guiding treatment algorithms for carotid intervention.

Serum lipoprotein (a) predicts acute coronary syndromes in patients with severe carotid stenosis

BACKGROUND

Different cut-off values of serum lipoprotein (a) [Lp (a)] were recently identified to better stratify cardiovascular risk categories. Both pathophysiological and prognostic values of Lp (a) remain unclear.

MATERIALS AND METHODS

Here, the prognostic value of Lp (a) and its correlation with intraplaque features were assessed in patients with severe carotid artery stenosis undergoing endarterectomy (n = 180). The cut-off value of 10 mg/dL for serum Lp (a) was selected to predict 24-month follow-up acute coronary syndrome (ACS). In addition, the association between serum Lp (a) and intraplaque lipids, collagen, inflammatory and vascular cells was assessed. Serum Lp (a) levels were measured by nephelometric assay.

RESULTS

Patients with high Lp (a) had similar comorbidities, medications and laboratory parameters as compared to low Lp (a) levels. At 24-month follow-up, patients with high Lp (a) had more ACS as compared to low levels. Histological parameters within plaques were comparable in the study groups. No significant correlation between Lp (a) serum levels and intraplaque parameters was found, except for a weak positive association with smooth muscle cells in upstream plaque portions. When adjusted for gender, the presence of dyslipidaemia and chronic coronary artery disease, Lp (a) ≥10 mg/dL remained predictive for ACS.

CONCLUSIONS

Lp (a) determination could be a useful tool to predict ACS in patients with severe carotid stenosis.

Lipoprotein(a) and coronary atheroma progression rates during long-term high-intensity statin therapy: Insights from SATURN

BACKGROUND & AIMS

Lipoprotein(a) [Lp(a)] is a low-density lipoprotein (LDL)-like particle that associates with major adverse cardiovascular events (MACE). We examined relationships between Lp(a) measurements and changes in coronary atheroma volume following long-term maximally-intensive statin therapy in coronary artery disease patients.

METHODS

Study of coronary atheroma by intravascular ultrasound: Effect of Rosuvastatin Versus Atorvastatin (SATURN) used serial intravascular ultrasound measures of coronary atheroma volume in patients treated with rosuvastatin 40 mg or atorvastatin 80 mg for 24 months. Baseline and follow-up Lp(a) levels were measured in 915 of the 1039 SATURN participants, and were correlated with changes in percent atheroma volume (ΔPAV).

RESULTS

Mean age was 57.7 ± 8.6 years, 74% were men, 96% were Caucasian, with statin use prior to study enrolment occurring in 59.3% of participants. Baseline [median (IQR)] LDL-cholesterol (LDL-C) and measured Lp(a) levels (mg/dL) were 114 (99, 137) and 17.4 (7.6, 52.9) respectively; follow-up measures were 60 (47, 77), and 16.5 (6.7, 57.7) (change from baseline: p < 0.001, p = 0.31 respectively). At baseline, there were 676 patients with Lp(a) levels <50 mg/dL [median Lp(a) of 10.9 mg/dL], and 239 patients with Lp(a) levels ≥ 50 mg/dL [median Lp(a) of 83.2 mg/dL]. Quartiles of baseline and follow-up Lp(a) did not associate with ΔPAV. Irrespective of the achieved LDL-C (<vs. ≥70 mg/dL), neither baseline nor on-treatment (<vs. ≥median) Lp(a) levels significantly associated with ΔPAV. No significant differences were observed in ΔPAV in Lp(a) risers versus non-risers, nor in those patients with baseline or on-treatment Lp(a) levels <vs. > 50 mg/dL.

CONCLUSIONS

In coronary artery disease patients prescribed long-term maximally intensive statin therapy with low on-treatment LDL-C levels, measured Lp(a) levels (predominantly below the 50 mg/dL threshold) do not associate with coronary atheroma progression. Alternative biomarkers may thus associate with residual cardiovascular risk in such patients.

Lipoprotein (a) as a cause of cardiovascular disease: insights from epidemiology, genetics, and biology

Human epidemiologic and genetic evidence using the Mendelian randomization approach in large-scale studies now strongly supports that elevated lipoprotein (a) [Lp(a)] is a causal risk factor for cardiovascular disease, that is, for myocardial infarction, atherosclerotic stenosis, and aortic valve stenosis. The Mendelian randomization approach used to infer causality is generally not affected by confounding and reverse causation, the major problems of observational epidemiology. This approach is particularly valuable to study causality of Lp(a), as single genetic variants exist that explain 27-28% of all variation in plasma Lp(a). The most important genetic variant likely is the kringle IV type 2 (KIV-2) copy number variant, as the apo(a) product of this variant influences fibrinolysis and thereby thrombosis, as opposed to the Lp(a) particle per se. We speculate that the physiological role of KIV-2 in Lp(a) could be through wound healing during childbirth, infections, and injury, a role that, in addition, could lead to more blood clots promoting stenosis of arteries and the aortic valve, and myocardial infarction. Randomized placebo-controlled trials of Lp(a) reduction in individuals with very high concentrations to reduce cardiovascular disease are awaited. Recent genetic evidence documents elevated Lp(a) as a cause of myocardial infarction, atherosclerotic stenosis, and aortic valve stenosis.

Evidence-based assessment of lipoprotein(a) as a risk biomarker for cardiovascular diseases - Some answers and still many questions

The present article is aimed at outlining the current state of knowledge regarding the clinical value of lipoprotein(a) (Lp(a)) as a marker of cardiovascular disease (CVD) risk by summarizing the results of recent clinical studies, meta-analyses and systematic reviews. The literature supports the predictive value of Lp(a) on CVD outcomes, although the effect size is modest. Lp(a) would also appear to have an effect on cerebrovascular outcomes, however the effect appears even smaller than that for CVD outcomes. Consideration of apolipoprotein(a) (apo(a)) isoforms and LPA genetics in relation to the simple assessment of Lp(a) concentration may enhance clinical practice in vascular medicine. We also describe recent advances in Lp(a) research (including therapies) and highlight areas where further research is needed such as the measurement of Lp(a) and its involvement in additional pathophysiological processes.

Lipoprotein (a) levels are not associated with carotid plaques and carotid intima media thickness in statin-treated patients with familial hypercholesterolemia

BACKGROUND

Lipoprotein (a), also called Lp(a), is a cardiovascular disease (CVD) risk factor. Statins do not lower Lp(a), this may at least partly explain residual CVD risk in statin-treated patients with familial hypercholesterolemia (FH). We investigated the association of Lp(a) levels with atherosclerosis in these patients.

METHODS AND RESULTS

We performed ultrasonography in 191 statin-treated FH patients (50% men; 48 ± 15 years) to detect carotid plaques and determine carotid intima-media thickness (C-IMT). Patients with high versus low Lp(a) levels (≤0.3 g/L) had similar plaque prevalence (36 and 31%, p = 0.4) and C-IMT (0.59 ± 0.12 and 0.59 ± 0.13 mm, p = 0.8). Patients with and without plaques had similar Lp(a) levels (median 0.35 (IQR: 0.57) and 0.24 (0.64) g/L, respectively, p = 0.4).

CONCLUSIONS

The Lp(a) levels were not associated with atherosclerosis in the carotid arteries of statin-treated FH patients. This suggests that adequate statin treatment delays carotid atherosclerosis in FH independently of Lp(a) levels.

Can and should carotid ultrasound be used in cardiovascular risk assessment?: the internist's perspective

Cardiovascular risk management is a major and challenging task for internists. Risk scores using algorithms based on traditional risk factors are helpful in identifying patients in whom intensive prevention strategies are warranted. However there remains a need for more accurate screening tools to allow clinicians to individualize the primary prevention programs to their patients. Approximately 40-80% of apparently healthy, asymptomatic subjects exhibit increased thickness of the lamina intima-media of the carotid artery or have atherosclerotic carotid plaques. These abnormalities can be measured safely and at low cost by ultrasound. Subclinical carotid lesions are strongly associated with generalized atherosclerotic burden and the risk of future cardiovascular events. Although many cardiovascular risk management guidelines recommend the use of these parameters incorporation in clinical practice is still not commonplace. Based on the current literature it can be stated that in high risk patients there is no additional value of carotid ultrasound because even in the absence of carotid lesions these patients should receive an intensive risk reduction regime. In the large low-intermediate risk group however carotid ultrasound findings carry subtle but possibly clinically relevant information about cardiovascular risk profile. The effect of treatment decisions based on carotid ultrasound parameters has not been studied. Sequential measurements to monitor progression and evaluate treatment response on an individual basis are not sufficiently reproducible. We therefore recommend the use of carotid ultrasound in low to intermediate risk patients but emphasize the importance of interpreting the results in conjunction with all cardiovascular risk factors and avoid follow-up measurements.

Association of serum proprotein convertase subtilisin/kexin type 9 with carotid intima media thickness in hypertensive subjects

OBJECTIVE

The clinical significance of the measurement of serum PCSK9 (proprotein subtilisin kexin type 9) is not well defined. This study investigated the association between serum PCSK9 levels and atherosclerosis assessed by carotid intima media thickness (IMT) in hypertensive patients.

METHODS

A total of 126 hypertensive patients over the age of 45 were enrolled. The maximum carotid IMT (max-IMT) and the mean carotid IMT (mean-IMT) were measured at the time of enrollment. Clinical and laboratory parameters including serum PCSK9 were analyzed.

RESULTS

Patients were divided into tertiles based on serum PCSK9 levels. After adjusting for age, sex, total cholesterol, HDL-cholesterol and triglyceride, max-IMT was significantly increased in the highest tertile of serum PCSK9 (0.969±0.033 vs 0.959±0.033 vs 1.077±0.033 mm, respectively; P=0.026). Mean-IMT showed a tendency to increase across the tertile groups (0.773±0.025 vs 0.790±0.026 vs 0.856±0.025 mm, respectively; P=0.059). Multivariate regression analysis revealed that serum PCSK9 was independently associated with carotid IMT (max-IMT: β=0.212, P=0.016; mean-IMT: β=0.184, P=0.04).

CONCLUSION

The present study is the first to report the association between serum PCSK9 levels and carotid IMT in hypertensive patients. These results suggest that serum PCSK9 may have a certain role in early pathogenesis of atherosclerosis.

Carotid Intima-Media Thickness in Asymptomatic Subjects With Low Lipoprotein(a) Levels

Background

Elevated and extreme circulating levels of lipoprotein(a) (Lp(a)) are considered to be an atherosclerotic risk factor, although additional studies on the low levels of Lp(a) are necessary to provide confirmation. The carotid intima-media thickness (CIMT) is known as a surrogate index of atherosclerosis. The aim of the present study was to investigate the correlation between the serum Lp(a) and CIMT in asymptomatic subjects with a relatively low Lp(a) level.

Methods

The study included 65 asymptomatic female Japanese subjects (mean age: 60 years) with a serum Lp(a) level < 30 mg/dL. Clinical data including the serum Lp(a) and CIMT were measured, and their correlations were examined.

Results

The median Lp(a) level was 18.6 mg/dL and the mean CIMT level was 0.8 mm. There was a significant and inverse correlation between the CIMT and Lp(a) (r = - 0.24, P ≤ 0.05), in addition to a significant and positive correlation between the CIMT and subject age and systolic blood pressure. A stepwise multiple linear regression analysis identified the Lp(a) to be correlated independently, significantly and inversely with the CIMT.

Conclusions

The Lp(a) levels were inversely correlated with the CIMT in this population, suggesting that subjects with a low Lp(a) level may have a predisposition to carotid atherosclerosis. This finding was preliminary and should be investigated further in larger studies and in additional settings.

Keywords

Lp(a); Carotid artery; IMT; Atherosclerosis

Lipoprotein(a) and family history of cardiovascular disease in children with familial dyslipidemias

OBJECTIVE

To investigate in children and adolescents with familial dyslipidemias the association between lipoprotein(a) [Lp(a)] level and family history of cardiovascular disease (CVD), and whether this association is independent of the disturbed lipid profile.

STUDY DESIGN

Lp(a) level, lipid profile, and a 2-generation genealogic tree to detect cardiovascular events were evaluated in 231 patients with familial dyslipidemias. Lp(a) levels were stratified according to presence, age of occurrence, and number and type of cardiovascular events in the patient's kindreds.

RESULTS

Lp(a) and other plasma lipid fractions did not differ between patients with and those without a family history of cardiovascular events. However, the percentage of patients with elevated Lp(a) level (≥85th percentile) was higher in those with a positive family history for early cardiovascular events (P = .01). Lp(a) level was a significant independent predictor of the number of premature cardiovascular events (β = 0.17; P = .01) and of cerebrovascular events in kindreds (OR, 2.5; 95% CI, 1.05-6.03; P = .039), independent of plasma lipid fractions and other cardiovascular risk factors.

CONCLUSIONS

In children and adolescents with familial dyslipidemias, the overall association between Lp(a) level and family history of early CVD may be due to a threshold effect in those with the highest Lp(a) levels. However, multiple cardiovascular events and cerebrovascular events are predicted by any increase in plasma Lp(a) level, independent of other cardiovascular risk factors.

Polymorphism in the apolipoprotein(a) gene, plasma lipoprotein(a), cardiovascular disease, and low-dose aspirin therapy

OBJECTIVE

A minor allele variant (rs3798220) of apolipoprotein(a) has been reported to be associated with elevated plasma lipoprotein(a) [Lp(a)] and increased cardiovascular risk. We investigated whether this allele was associated with elevated Lp(a) and cardiovascular risk in the Women's Health Study, a randomized trial of low-dose aspirin, and whether aspirin reduced cardiovascular risk in minor allele carriers.

METHODS AND RESULTS

Genotypes of rs3798220 were determined for 25,131 initially healthy Caucasian participants. Median Lp(a) levels at baseline were 10.0, 79.5, and 153.9mg/dL for major allele homozygotes, heterozygotes, and minor allele homozygotes, respectively (P<0.0001). During the 9.9 years of follow-up, minor allele carriers (3.7%) in the placebo group had twofold higher risk of major cardiovascular events than non-carriers (age-adjusted hazard ratio (HR)=2.21, 95% CI: 1.39-3.52). Among carriers, risk was reduced more than twofold by aspirin: for aspirin compared with placebo the age-adjusted HR was 0.44 (95% CI: 0.20-0.94); risk was not significantly reduced among non-carriers (age-adjusted HR=0.91, 95% CI: 0.77-1.08). This interaction between carrier status and aspirin allocation was significant (P=0.048).

CONCLUSIONS

In the Women's Health Study, carriers of an apolipoprotein(a) variant had elevated Lp(a), doubled cardiovascular risk, and appeared to benefit more from aspirin than non-carriers.

Study of the intima-media thickening in carotid arteries of healthy elderly with high blood pressure and elderly with high blood pressure and dyslipidemia

OBJECTIVE

The objective of this study was to assess the mean intima-media thickening of carotid arteries of elderly subjects, and its relationship with age, anthropometric measurements, high systolic blood pressure and dyslipidemia.

METHODS

In this investigation, 129 subjects were enrolled between 1995 and 1998, age ranging from 29 to 94 years. They were assigned to one of 4 groups, including 2 control groups (group I, of healthy younger subjects; group II of healthy elderly subjects). Groups III and IV included those who presented with isolated systolic hypertension (ISH), and ISH and dyslipidemia, respectively. All subjects were submitted to a medical interview, lab tests with measurement of cholesterol levels, electrocardiogram, and carotid ultrasound. The ultrasound included measurement of the intima-media thickening (IMT) of the carotid arteries, the right carotid artery (RCA) and left carotid artery (LCA), and assessment of the presence of plaques. Blood fat and glucose were measured by a standard method. The results were compared among the groups through statistical tests. The tests employed were: Chi-Square, Pearson's and Likelihood Ratio, Student's t, Mann-Whitney; ANOVA followed by Tukey's test, Kruskal-Wallis nonparametric test, and test for multiple comparisons and Odds Ratio determination (OR).

RESULTS

In this investigation, a positive association was observed between aging and IMT. In relation to systolic hypertension, a significant association was observed with IMT (IMT-RCA p = 0.0034; IMT-LCAp = 0.0196; IMT-RLCAp = 0.0299), and with the presence of plaques (PlaqueR p = 0.0110; PlaqueL p = 0.0294; PlaqueRL p = 0.0040).

CONCLUSION

This investigation evidenced the important role of aging in IMT, and of systolic hypertension in the IMT and presence of plaque. However, further studies are needed for a better understanding of the actual role of risk factors in aging.

Clinical Use of Carotid Intima-Media Thickness: Review of the Literature

Carotid intima-media thickness (CIMT) is a simple and inexpensive tool to assess the cumulative effect of atherosclerotic risk factors and is an independent predictor of future cardiovascular risk. CIMT is commonly used as a surrogate end point in research trials as a marker of atherosclerosis. However, new software programs have made CIMT a clinically practical examination for risk evaluation. CIMT correlates with cardiac risk factors and is an independent predictor of future myocardial infarction and stroke risk. Tests for subclinical atherosclerosis, such as CIMT, will help clinicians to more effectively identify the vulnerable patient who would benefit from aggressive prevention intervention.

Elevated Lipoprotein(a) does not promote early atherosclerotic changes of the carotid arteries in young, healthy adults

BACKGROUND

Elevated levels of Lipoprotein(a) [Lp(a)] have been linked to an increased risk of ischemic cardiovascular events. Yet the mechanism by which Lp(a) might contribute to this increased risk is not clear.

METHODS

To elucidate whether high plasma levels of Lp(a) contribute to the development of early atherosclerotic vessel wall changes, the intima-media thickness of the common carotid arteries [CCA-IMT] of 151 healthy young volunteers without additional relevant cardiovascular risk factors was measured by high-resolution ultrasound. Plasma concentrations of Lp(a) were quantified and other established risk factors, such as body mass index [BMI], plasma levels of cholesterol, triglycerides and homocysteine, were determined. Furthermore, the carotid arteries were examined for the presence of plaques and stenoses.

RESULTS

Univariate analysis showed a significantly negative correlation of CCA-IMT with HDL cholesterol and positive correlations with age, BMI, total and LDL cholesterol, triglycerides and even with homocysteine, but not with Lp(a). When the study population was dichotomized according to Lp(a) levels, no statistically significant differences in CCA-IMT could be detected between persons with plasma Lp(a)<300mg/l or >or=300mg/l, respectively.

CONCLUSION

Our data suggest that elevated Lp(a) levels alone do not contribute to increased cardiovascular risk by promoting early atherogenesis in vivo.

Association of serum lipoprotein(a) with ultrasonographically determined early atherosclerotic changes in the carotid and femoral arteries in kidney transplanted patients

OBJECTIVES

To evaluate the association of serum lipoprotein(a) [Lp(a)] with carotid intimal media thickness (IMT) and carotid femoral plaque occurrence in kidney transplant patients.

PATIENTS AND METHODS

Fifty-four subjects included 29 group 1 normal healthy persons and 25 group 2 kidney transplant patients underwent carotid IMT measurements and carotid femoral plaque assessment by B-mode ultrasonography. Also we measured cholesterol, triglyceride, HDL-C, LDL-C and Lp(a) as well as BUN and creatinine.

RESULTS

There was a significant difference between Lp(a) in the two groups (P = .016). There was a significant difference between carotid IMT of the two groups (P < .001). Moreover there was a significant difference between the plaque scores of kidney transplant patients and the normal group (P = .05). There were no correlations between carotid IMT and plaque score in normal subjects or in kidney transplant patients (P > .05). There was a significant correlation between carotid IMT with age in Group 1 (P = .035). No correlation between carotid IMT and serum Lp(a) was seen in the two groups. No significant correlations between plaque score and serum Lp(a) were observed. There was no correlation between duration of transplant and thickening of intimal media complex in this group. In this group a positive correlation was demonstrated between carotid IMT with serum LDL-C (P < .001).

CONCLUSIONS

Age was the most important factor associated with thickening of intimal media complex in normal subjects and in plaque formation in the renal transplant group. Serum LDL-C may be associated with thickening of intimal media complex in kidney transplant patients. Serum Lp(a) may not be a significant factor in thickening of the intimal media complex or plaque occurrence in kidney transplant patients.

Non-HDL Cholesterol as a Predictor of Carotid Atherosclerosis in the Elderly

The aim of the present study was to evaluate sclerotic lesions of the common carotid artery by ultrasonography in 921 in-patients aged 65 years and older (77 +/- 7 years) and investigate whether lipid levels were associated with carotid atherosclerosis. In men, an increased risk for carotid atherosclerosis was associated with increased levels of low-density lipoprotein cholesterol (LDL-C) and non-high-density lipoprotein cholesterol (non-HDL-C). Compared to men with the lowest tertile of LDL-C levels (< 83.4 mg/dl), the adjusted odds ratio was 2.502 (95% confidence interval: 1.426-4.390) in those with the middle tertile (83.4-115.2 mg/dl), and 2.688 (1.509-4.790) in those with the highest tertile ( > 115.2 mg/dl). Like the LDL-C level, the non-HDL-C level showed a positive and linear relationship with carotid atherosclerosis. Compared to men with the lowest tertile of non-HDL-C levels ( < 101 mg/dl), the adjusted odds ratio was 2.881 (1.633-5.081) for those with the middle tertile (101-135 mg/dl), and 2.990 (1.651-5.415) for those with the highest tertile ( > 135 mg/dl). Similarly, in women, an increased risk for carotid atherosclerosis was also positively and linearly associated with LDL-C and non-HDL-C. The Non-HDL-C level is a potential predictor of risk for carotid atherosclerosis in the elderly.

Long-Term Effects of Lipoprotein(a) on Carotid Atherosclerosis in Elderly Japanese

BACKGROUND

Serum level of lipoprotein(a) [Lp(a)] is hereditarily constant throughout life within an individual, but the relationship between Lp(a) and atherosclerosis in elderly people is still controversial.

METHODS

Serum Lp(a) levels were studied in 208 elderly Japanese participants aged 80 years with a variety of diseases, using carotid ultrasonography (US), brain computerized tomography (CT), electrocardiography (ECG), and ankle brachial pressure index (ABPI). Carotid plaque lesions were divided into 3 types based on the US echogenicity assessed by a computer-assisted system: L type (hypoechoic plaque), H type (hyperechoic plaque), and M type (heterogeneous plaque).

RESULTS

The frequency of the L type and occlusion was significantly higher in the high Lp(a) group (n = 38) than in the normal Lp(a) group (n = 170). The mean height of the plaque was also greater in the high Lp(a) group than in the normal Lp(a) group. There was no difference in CT findings between the two groups. Myocardial ischemia on ECG and low ABPI (<0.9) were both frequently, but not significantly, seen in the high Lp(a) group. Among factors influencing US findings, multiple regression analysis showed that high Lp(a) correlated markedly to L type and cigarette smoking correlated to M type.

CONCLUSIONS

These findings indicate that, in Japanese elderly patients aged 80, serum Lp(a) strongly correlates with hypoechoic carotid lesions, which correspond histologically to lipid-rich, unstable atherosclerosis. This suggested that Lp(a) could promote the formation of atherosclerosis throughout life, and play a role as an independent risk factor for circulatory disturbance of the organ later in life.

Relationship of lipoprotein(a) with intimal medial thickness of the carotid artery in Type 2 diabetic patients in south India

OBJECTIVE

The objective of this study was to investigate the association of lipoprotein(a) [Lp(a)] levels with intimal medial thickness (IMT) in Type 2 diabetic patients in south India.

STUDY DESIGN

We studied 587 consecutive Type 2 diabetic patients at the M.V. Diabetes Specialities Centre, Chennai. The mean age of the study group was 55 +/- 10 years and 71.2% were males. IMT of the right common carotid artery was determined using high-resolution B mode ultrasonography. Lp(a) levels were measured using ELISA. Since the frequency distribution of Lp(a) was skewed, Lp(a) values were log transformed and the geometric mean was used for statistical analysis. The tertiles of IMT were determined to analyse the association of Lp(a) and other factors with IMT.

RESULT

The mean Lp(a) level in the study patients was 18.9 +/- 3.1 mg/dl (geometric mean +/- sd) and the mean IMT of the study subjects was 0.93 +/- 0.19 mm (mean +/- sd). The prevalence of carotid atherosclerosis (defined as IMT > 1.1 mm) among subjects with elevated Lp(a) levels > 20 mg/dl was significantly higher compared with those with Lp(a) levels </= 20 mg/dl (26.9% vs. 16.3%, P = 0.003). Lp(a) levels increased with increase in tertiles of IMT (anova, P < 0.05). Pearson correlation analysis of carotid IMT with other cardiovascular risk factors revealed strong correlation of IMT with age (P < 0.0001), duration of diabetes (P < 0.0001), systolic blood pressure (P < 0.0001), diastolic blood pressure (P = 0.006), LDL-cholesterol (P = 0.023), HbA1c (P = 0.017) and Lp(a) (P < 0.0001). Multiple logistic regression analysis showed age (P = 0.010), LDL-cholesterol (P = 0.032) and Lp(a) (P = 0.021) to be associated with carotid atherosclerosis.

CONCLUSION

The results suggest that Lp(a) has a strong association with IMT of carotid arteries in Type 2 diabetic subjects in south India.

Lipoprotein(a) and ultrasonographically determined early atherosclerotic changes in the carotid and femoral artery

Recent studies suggest that high lipoprotein(a) [Lp(a)] plasma levels are associated with symptomatic ischemic cardiovascular disease. We examined whether Lp(a) plasma levels are associated with early atherosclerotic vessel wall changes in a group of asymptomatic subjects. In a group of 142 asymptomatic men, the intima-media thickness (IMT) in the common carotid artery, the carotid bifurcation and the common femoral artery was determined by B-mode ultrasonography. In addition to Lp(a) levels, established risk factors, such as blood pressure and cholesterol levels were determined. Lipoprotein(a) values ranged from 2 mg L(-1) to 900 mg L(-1) (median 145 mg L(-1)). Linear regression analysis showed a clear association of IMT with the established risk factors but not with Lp(a) [regression coefficient carotid artery -0.0003, 95% confidence interval (CI) -0.002-0.001; regression coefficient femoral artery -0.0003, 95% CI -0.004-0.003]. We found no increased intima-media thickness in the carotid or femoral artery at high levels of Lp(a). Lipoprotein(a) levels are not associated with early atherosclerotic vessel wall changes in the carotid or femoral artery.

Relation of lipid and lipoprotein(a) to ischaemic stroke

The relationship of lipids and Lp(a) to ischemic stroke hasn't been established yet. Our aim was to determine lipid profile and vascular risk factors in stroke patients and compare them with control subjects. Seventy-nine consecutive patients with ischemic stroke were analyzed by total cholesterol, HDL-C, LDL-C, triglyceride, Lp(a) and doppler ultrasonography and vascular risk factors were recorded. Thirty control subjects of same ages were compared with the patient group. Lp(a) and lipids were correlated with stroke subtype and carotid atherosclerosis. There was no statistical significance between patients and control subjects related to total cholesterol, triglyceride, HDL-C, LDL-C and Lp(a) (P>0.05). Atherotrombotic and lacunar strokes didn't show any difference correlated with lipids and Lp(a). Hypertension and diabetes mellitus were important risk factors with (OR=4.50, 95% CI=1.25-16.22) and (OR=4.43, 95% CI=1.79-10.93) respectively. These results were statistically significant (P<0.05). Total cholesterol (308.67+/-85.82) and Lp(a) (32.10+/-17.30) values showed statistical significance (P<0.05) in patients with marked stenosis when compared with patients of normal doppler ultrasonography. Hypertension and diabetes mellitus were found as independent risk factors for ischemic stroke. Lipids and Lp(a) were not independent for atherotrombotic and lacunar stroke. Lp(a) concentration and carotid atherosclerosis in ultrasonography were associated significantly.

Classic risk factors, hypercoagulability and migraine in young women with cerebral lacunar infarctions

OBJECTIVE

Lacunar cerebral infarctions (LACI) in young women is a rare condition which pathogenesis is still not fully recognized. We explored the presence of classic risk factors, hypercoagulability and migraine in young women with LACI.

METHODS

Charts of 192 consecutive premenopausal women suffering cerebrovascular insult [125 (65%) haemorhagic, 58 (30%) ischaemic and 9 (5%) unclassified] during a period of 5 years were reviewed. Sixteen out of 58 (27%) patients with ischaemic stroke were identified to have LACI and included in a study.

RESULTS

Ten and seven out of 16 LACI women had at least one classical risk factor (hypertension, hyperlipidaemia, smoking or oral contraceptives) or migraine, respectively. LACI patients had slight hypercoagulable state indicated by shorter thrombin and thromboplastin times, higher fibrinogen and higher t-PA antigen than 47 age matched controls (all P < 0.05). In addition in LACI patients with migraine the trend toward more pronounced hypercoagulable state in comparison to LACI patients without migraine was found. The combination of migraine, at least one classic risk factor and hypercoagulability was present in 5/16 (31.25%) of patients.

CONCLUSIONS

The combination of slightly to moderately expressed classic risk factors, hypercoagulability and migraine might be a risk profile for LACI in young women. Further studies are needed to clarify risk profile, rather than isolated risk factors, for LACI in a specific group as young women are.

Detection of lipoprotein(a) in intraparenchymal cerebral vessels: correlation with vascular pathology and clinical history

Serum levels of lipoprotein(a), Lp(a), have been shown to be associated with increased risk of atherosclerosis (AS) and AS-related diseases such as myocardial and ischemic cerebral infarcts (ICI). Lp(a) has been detected in the vascular wall of the aorta and coronary vessels, and we documented the presence of apo(a) in cerebral vessels of the Circle of Willis, associated with AS changes. In this study we further investigated and characterized the biochemical nature of Lp(a) detected in both large and small cerebral parenchymal vessels. Autopsy specimens of cerebral vessels of 51 patients were examined by immunohistochemistry with monoclonal antibodies against apo(a), apoB, and plasminogen. Lp(a) was detected in cerebral capillaries and arterioles. All of the 8 patients with ICI expressed Lp(a) in parenchymal vessels, generally (6/8) in both capillaries and arterioles. Of 43 patients without ICI only 25 had Lp(a) detected. Among the patients without ICI, there was a slightly increased incidence of parenchymal Lp(a) in those patients who had severe hypoxic brain damage (12/20) compared to those patients without severe hypoxic damage (9/23). Thus, the presence of Lp(a) in small cerebral parenchymal vessels may reflect the role of Lp(a) in ICI.

Smoking is associated with dose-related increase of intima-media thickness and endothelial dysfunction

Cigarette smoking is firmly established as a risk factor for atherosclerosis. However, the exact mechanism causing smoking-related damage to the arterial wall and its relation to the atherosclerotic process is not known. Also unknown is the time delay between the start of smoking and the sequence of functional and morphologic changes occurring in the arterial wall caused by smoking and their interrelationship. Therefore, the aim of this study was to evaluate the acute and chronic effects of smoking on endothelium-dependent (flow-mediated) dilation (FMD) of the peripheral arteries, the effects of dose and duration of chronic smoking on intima-media thickness (IMT) of the carotid arteries, and their interrelationship. The study encompassed two groups of smokers. In group A there were 40 subjects of both sexes, who smoked on average 17.6 +/- 6.5 cigarettes per day, for 5 to 15 years (mean 8.95 +/- 4.0 years), mean age 28.1 years. Group B consisted of 42 smokers of both sexes who smoked 21.15 +/- 8.2 cigarettes/day for more than 15 years (mean 21.15 +/- 3.4 years), mean age 39.5 years. The control group consisted of 40 healthy subjects without major risk factors of atherosclerosis, mean age 29.1 years. By means of high-resolution ultrasound the brachial artery diameter was measured at rest and during reactive hyperemia (after release of a forearm tourniquet) and the flow-mediated, endothelium-dependent dilation was calculated. The IMT of the carotid arteries was determined in all subjects by use of B-mode ultrasonography. Resting blood flow in the brachial arteries was significantly less in the smokers' groups than in controls (78.8 +/- 31.9 vs 134.9 +/- 45.0 mL/min, p<0.0001). This decrease was much more evident in female than in male smokers. Female smokers also had significantly smaller brachial artery diameter at rest. In smokers the FMD of the brachial artery was reduced (11 +/- 4% vs 7 +/- 4%, p<0.004) and the mean IMT was significantly greater than in controls (0.68 +/- 0.13 vs 0.59 +/- 0.04 mm, p<0.001). Impairments of FMD and IMT increase were related to the duration and to the number of cigarettes smoked. In all subjects IMT was significantly correlated with total and LDL cholesterol, fibrinogen, lipoprotein(a) concentration, body mass index, and age of the subjects, but multivariate analysis showed that only total dose smoked and fibrinogen concentration were independently related to IMT. The results of this study show that smoking is associated with dose-related impairment of FMD and increased IMT of the carotid arteries. Impairment of FMD occurs in smokers very early and is the earliest detectable event, preceding morphologic changes of the vessel wall. Some harmful effects of smoking on the vessel wall are gender related.

Biochemical risk factors and patient's outcome: the case of lipoprotein(a)

Lipoprotein(a) (Lp(a)) is a genetic variant of low density lipoproteins and consists of the covalent association of the unique and enigmatic apolipoprotein(a) to apoliprotein B100. Despite the high degree of homology with low density lipoproteins, Lp(a) displays distinctive physico-chemical properties, function and metabolism. The present article reviews the main biological and clinical evidences about the association between raised concentration of Lp(a) and atherothrombotic diseases and provides tentative guidelines to improve the clinical usefulness of Lp(a) measurements.

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.

Does lipoprotein(a) impair endothelial function?

OBJECTIVES

This study was undertaken to test the hypothesis that lipoprotein(a) [Lp(a)] impairs endothelial function.

BACKGROUND

Elevated Lp(a) plasma levels have been demonstrated to be associated with an increased risk of coronary heart disease. In atherosclerosis, endothelial dysfunction is known to be an early indicator of vascular changes. However, the effect of Lp(a) on nitric oxide (NO)-dependent vasodilator response has not yet been determined. We therefore examined the influence of Lp(a) on basal and stimulated NO-mediated vasodilator response in the forearm vascular bed.

METHODS

Strain gauge plethysmography was used to measure changes in forearm blood flow produced by intraarterial infusion of increasing doses of acetylcholine (3, 12, 24 and 48 microg/min), sodium nitroprusside (200, 800 and 3,200 ng/min) and N-monomethyl L-arginine (L-NMMA) (1, 2 and 4 micromol/min) in 57 white subjects (mean age +/- SD 37 +/- 14 years). Lp(a) plasma concentrations were determined by rocket immunoelectrophoresis.

RESULTS

Endothelium-dependent vasodilation tested by intraarterial acetylcholine and endothelium-independent vascular relaxation tested by intraarterial sodium nitroprusside were not correlated with Lp(a). Similarly, no significant differences in forearm blood flow changes were observed when patients were classified into tertiles according to their individual Lp(a) concentration. In contrast, changes in forearm blood flow after intraarterial L-NMMA indicating basal production and release of NO differed significantly among tertiles. Patients in the highest Lp(a) tertile (49.2 +/- 20.3 mg/dl) had a much greater vasoconstrictive response to L-NMMA than patients in the lowest Lp(a) tertile (4.8 +/- 2.5 mg/dl): 2 micromol/min of L-NMMA, -23.6 +/- 22.5% vs. -10.4 +/- 9.1% (p < 0.02); 4 micromol/min of L-NMMA, -27.8 +/- 10.3% vs. -17.6 +/- 9.9% (p < 0.03). Lp(a) plasma level consistently correlated negatively with the forearm blood flow responses to 4 micromol/min of intraarterial L-NMMA (r = -0.38, p < 0.01). Multiple stepwise regression analysis of variables, including total and high and low density lipoprotein cholesterol, further confirmed that plasma Lp(a) remained a significant independent determinant of forearm blood flow changes in response to L-NMMA (p < 0.02).

CONCLUSIONS

The endothelium-dependent vasoconstrictive response to L-NMMA was enhanced in subjects with relatively high Lp(a) plasma levels, suggesting an increased basal production and release of NO. This response seemed to reflect a compensatory mechanism of the endothelium to yet unknown Lp(a)-induced atherosclerotic effects.

Standardization and clinical management of lipoprotein(a) measurements

The present article proposes personal suggestions to improve determinations and clinical interpretation of results of lipoprotein(a) assays. Methods and procedures for sampling and quantification of the various isoforms of lipoprotein(a) in serum, plasma and urine are reviewed with the aim of improving the reliability and reproducibility of results and reinforcing the clinical utility of lipoprotein(a) measurements.