Lipoprotein(a) is not associated with coronary heart disease in the elderly: cross-sectional data from the Dubbo study

Apolipoprotein(a), an enigmatic anti-angiogenic glycoprotein in human plasma: A curse or cure?

Angiogenesis is a finely co-ordinated, multi-step developmental process of the new vascular structure. Even though angiogenesis is regularly occurring in physiological events such as embryogenesis, in adults, it is restricted to specific tissue sites where rapid cell-turnover and membrane synthesis occurs. Both excessive and insufficient angiogenesis lead to vascular disorders such as cancer, ocular diseases, diabetic retinopathy, atherosclerosis, intra-uterine growth restriction, ischemic heart disease, stroke etc. Occurrence of altered lipid profile and vascular lipid deposition along with vascular disorders is a hallmark of impaired angiogenesis. Among lipoproteins, lipoprotein(a) needs special attention due to the presence of a multi-kringle protein subunit, apolipoprotein(a) [apo(a)], which is structurally homologous to many naturally occurring anti-angiogenic proteins such as plasminogen and angiostatin. Researchers have constructed different recombinant forms of apo(a) (rhLK68, rhLK8, RHACK2, KV-11, and AU-6) and successfully exploited its potential to inhibit unwanted angiogenesis during tumor metastasis and retinal neovascularization. Similar to naturally occurring anti-angiogenic proteins, apo(a) can directly interfere with angiogenic signaling pathways. Besides this, apo(a) can also exert its anti-angiogenic effect indirectly by inducing endothelial cell apoptosis, by inhibiting endothelial progenitor cell functions or by upregulating nuclear factors in endothelial cells via apo(a)-bound oxPLs. However, the impact of the anti-angiogenic potential of native apo(a) during physiological angiogenesis in embryos and wounded tissues is not yet explored. In this context, we review the studies so far done to demonstrate the anti-angiogenic activity of apo(a) and the recent developments in using apo(a) as a therapeutic agent to treat impaired angiogenesis during vascular disorders, with emphasis on the gaps in the literature.

High levels of lipoprotein (a) and premature acute coronary syndrome

BACKGROUND AND AIMS

High levels of lipoprotein(a) [Lp(a)] are associated with increased risk of acute coronary syndrome (ACS). We explored whether Lp(a) exhibits a stronger association with premature ACS.

METHODS

A case-control study was conducted; 1457 patients with a history of ACS (54.8 ± 13 years, 86% males) and 2090 age-sex matched adults free of cardiovascular disease were enrolled. Bio-clinical characteristics [risk factors, low-density lipoprotein-cholesterol, Lp(a)] were derived through standard procedures.

RESULTS

A 10 mg/dL increase in Lp(a) was associated with 4% (95% CI, 1.01 to 1.02) higher likelihood of having ACS in younger (<45 years) and 2% (95% CI, 1.01 to 1.02) higher likelihood in middle-aged (45-60 years) individuals. Adjusting for common risk factors, elevated Lp(a), i.e. >50 mg/dL, was still associated with increased likelihood of ACS in younger adults (<45 years) (OR = 2.88, 95% CI, 1.7 to 4.6) and in middle aged ones (45 and 60 years) (OR = 2.06, 95% CI, 1.4 to 3.2), but not in older participants (>60 years) (OR = 1.31, 95% CI, 0.8 to 2.4).

CONCLUSIONS

Lp(a) seems to be an independent risk factor for ACS in individuals <45 years, and high Lp(a) levels increase by ∼3folds the risk for ACS. The association is preserved but is less in middle-aged individuals (45-60 years) and is abolished >60 years.

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.

All-cause mortality and competing risks of fatal and nonfatal vascular events in the Italian longitudinal study on aging: impact of lipoprotein(a)

Among possible determinants of vascular events, the role of high lipoprotein(a) (Lp[a]) serum levels represents a still uncertain independent risk factor in elderly populations. Moreover, the cumulative incidence of nonfatal vascular events due to high Lp(a) serum levels is conditioned by the competing risk of death from any causes that are a function of age. After a 6.3-year median follow up, we tested the competing risks of all-cause mortality, cumulative fatal-nonfatal stroke events, cumulative fatal-nonfatal coronary artery disease (CAD) events, and nonfatal stroke or CAD events due to high Lp(a) serum levels in a population-based, prospective study conducted in one of the eight centers of the Italian Longitudinal Study on Aging (ILSA), Casamassima, Bari, Italy. Of 704 elderly individuals (65-84 years), 372 (169 women and 203 men) agreed to participate in the study. As compared with those in the lowest Lp(a) tertile serum levels, subjects in the highest tertile (>20 mg/dL) had a higher partially adjusted risk of nonfatal CAD (hazard ratio, 4.19; 95% confidence interval [CI], 1.36-12.94) and nonfatal stroke (hazard ratio, 3.38; 95% CI, 1.00-11.56). Compared with those in the lowest tertile, subjects in the highest tertile had a higher fully adjusted risk of nonfatal CAD (hazard ratio, 3.41; 95% CI, 1.08-10.78). Finally, overall no statistically significant association was found between Lp(a) and the risk of all-cause mortality, cumulative fatal-nonfatal stroke, and cumulative fatal-nonfatal CAD events. In our population, Lp(a) was not a significant independent predictor of stroke and death from all causes, but it was an independent predictor of nonfatal CAD. Finally competing risk, conditioning the timing and occurrence of vascular events in our study population, could be a correct approach for evaluating the role of Lp(a) lipoprotein in vascular disease among elderly people.

Lipoproteins, vascular-related genetic factors, and human longevity

The relationships among lipoprotein metabolism, genetic vascular factors, vascular disease, and Alzheimer's disease suggest that the examination of centenarian populations in relation to certain genes or lipoprotein metabolism provide insights into human longevity. The findings on the higher frequency of the apolipoprotein E epsilon4 allele in middle-aged subjects than in centenarians were substantially confirmed. On the contrary, recent findings did not confirm previous data on increased prevalence of the high-risk angiotensin I converting enzyme D allele in French centenarians. The variability in the strength of association between angiotensin I converting enzyme polymorphism and longevity could be related to regional differences in angiotensin I converting enzyme D allele frequency in Europe recently showed, as also recently reported for apolipoprotein Eepsilon2 and epsilon4 allele in centenarians. Indeed some studies of lipoprotein profiles in centenarians have also had contradictory outcomes, with evidence of lower serum levels of high-density lipoprotein cholesterol, with higher high-density lipoprotein 2 cholesterol subfraction, larger high-density lipoprotein and low-density lipoprotein particle sizes, and higher lipoprotein(a) concentration in centenarians, which is apparently disadvantageous for human longevity. Elevated lipoprotein(a) serum levels, increasing the risk for cerebrovascular disease, may play a role in determining clinical Alzheimer's disease, but lipoprotein(a) elevation in centenarians, in the absence of other coronary artery disease risk factors, appears as a positive survival factor. In different populations, there are significant trends in the reduction of serum apolipoprotein E levels from apolipoprotein E epsilon2- to epsilon4-carriers and significant differences in serum apolipoprotein E levels with respect to age in epsilon4-carriers but only after adjustment for high-density lipoprotein cholesterol. While further studies are needed to confirm the possible role of apolipoprotein E concentration as putative longevity factor this paper provides an overview of many of the investigated vascular factors with respect to longevity.

Efficacy and tolerability of combined treatment with L-carnitine and simvastatin in lowering lipoprotein(a) serum levels in patients with type 2 diabetes mellitus

Lipoprotein(a) [Lp(a)] concentration is generally related to coronary artery disease (CAD) and cerebrovascular disease. However, at present, few interventions are available to lower Lp(a) concentrations. We investigated the effects of l-carnitine, co-administered with simvastatin, on hyper-Lp(a) in patients with type 2 diabetes mellitus. We conducted an open, randomised, parallel-group study, in one investigational center (University hospital). Fifty-two patients with type 2 diabetes mellitus, a triglyceride serum levels <400mg/dL (<4.5 mmol/L), and Lp(a) serum levels >20mg/dL (0.71 mmol/L) were randomised to receive simvastatin alone (n=26) or simvastatin plus l-carnitine (n=26) for 60 days. Simvastatin was administered, in both groups, at a dosage of 20 mg/day, while l-carnitine was administered at a dosage of 2g/day once daily. Both treatments were given orally. Serum levels of triglycerides, total cholesterol, LDL cholesterol, high-density lipoprotein (HDL) cholesterol, non-HDL cholesterol (total cholesterol minus HDL cholesterol), apolipoprotein B, and Lp(a) were measured at baseline and 60 days after starting treatment. No difference in time by groups (simvastatin and simvastatin plus l-carnitine) were observed in the reduction of LDL cholesterol, non-HDL cholesterol, and apoB serum levels. On the other hand, Lp(a) serum levels increase from baseline to 60 days in the simvastatin group alone versus a significant decrease in the combination group. Our findings provide support for a possible role of combined treatment with l-carnitine and simvastatin in lowering Lp(a) serum levels in patients with type 2 diabetes mellitus than with simvastatin alone. Our results strongly suggest that l-carnitine may have a role among lipid-lowering strategies.

Secondary prevention and referral of elderly patients to a cardiovascular lipid service

The burden of cardiovascular disease in the elderly has increased interest in lipid profiles which retain associations with outcome except at extreme age and for which management has benefits at least in secondary prevention. The source, clinical and laboratory background of 90 male and 120 female consecutive referrals age >70 years to a specialist cardiovascular lipid service have been analysed. Main sources were vascular surgery 47%, cardiology 9% and general practice 41% with 6% referred through routine health checks. Presenting lipids (mM: mean+/-S.D.) were: males: cholesterol 6.9+/-1.7, triglycerides 2.3+/-1.5, HDL 1.2+/-0.3; females: cholesterol 7.8+/-1.4, triglycerides 2.1+/-1.3, HDL 1.5+/-0.5, consistent with greater awareness of lipid-related problems in males but significant vascular disease in females. Secondary lipemia was defined in 131/210, 62.3% of patients (83 recognised before clinic presentation, 48 found at follow-up, mainly diabetes). Significant vascular disease was identified in 166/210 patients, significant other risk factors in another 35 patients. Levels of lipoprotein(a) were widely distributed for all groups, but elevated against population profiles for all groups with vascular disease. Referrals were monitored and not routinely accepted: reassuringly most then accepted were justified through atheroma-related disease and opportunities for secondary prevention, with little additional burden through untargeted routine health checks. Recognition of and management of secondary lipemia and obesity were however incomplete.

Relation of lipoprotein(a) as coronary risk factor to type 2 diabetes mellitus and low-density lipoprotein cholesterol in patients > or =65 years of age (The Italian Longitudinal Study on Aging)

High levels of serum lipoprotein(a) [Lp(a)] have been associated with increased risk of coronary artery disease (CAD), but this association apparently is not confirmed in elderly people. We evaluated the interactions of Lp(a) with lipid and nonlipid CAD risk factors in a sample of subjects enrolled in the prevalence survey (1992 to 1993) of the Italian Longitudinal Study on Aging (ILSA). The entire population consisted of 5,632 elderly people, aged 65 to 84 years, randomly selected in 8 Italian municipalities. The present cross-sectional study included 400 free-living elderly subjects (74 +/- 6 years) from the randomized cohort of Casamassima (Bari, Southern Italy) (n = 704). The results showed that in the elderly population, high serum Lp(a) is a CAD risk factor dependent on type 2 diabetes mellitus and elevated low-density lipoprotein (LDL) cholesterol levels. In particular, the combined effect of high Lp(a) (> or =20 mg/dl) and high LDL cholesterol (> or =3.63 mmol/L [> or =140 mg/dl]), increases coronary risk by 2.75 (95% confidence interval 7.70 to 0.99); finally, the effect of Lp(a) > or =20 mg/dl and LDL cholesterol > or =3.63 mmol/L (> or =140 mg/dl), combined with type 2 diabetes mellitus, increases risk of CAD by 6.65 (95% confidence interval 35.40 to 1.25). In the elderly, elevated Lp(a) levels appear not to be an independent predictor of CAD, but this lipoprotein is a risk factor only in subjects with type 2 diabetes mellitus and elevated LDL cholesterol.

Response of Blood Lipids to Physical Exercise in Elderly Subjects

Regular physical activity plays an important role in nonpharmacologic management of hyperlipidemia, in both the primary and secondary prevention of coronary heart disease. Training intensity and duration, health status (especially the presence of cardiovascular disease), and concomitant changes in body mass and dietary habits are the most important factors that can modify the physical activity-blood lipid profile relationship in the elderly. The benefit of regular exercise goes beyond direct influence on blood lipids; it aids in reducing weight, decreasing fat mass, increasing lean body mass, reducing elevated blood pressure, and increasing insulin sensitivity. Regular physical activity has become widely recommended as an important element of healthy and successful aging and should be encouraged in individuals without contraindications. (c)2001 CHF, Inc.

Cholesterol and other lipids predict coronary heart disease and ischaemic stroke in the elderly, but only in those below 70 years

The prediction of coronary heart disease (CHD) and stroke by total and low density lipoprotein (LDL) cholesterol in older persons remains problematical. This study tests the hypothesis that cholesterol and other risk factors may be differentially predictive of CHD and ischaemic stroke in older persons when they are segregated into different age groups. CHD and ischaemic stroke outcomes were recorded during 129 months follow-up in a cohort of 2805 men and women of 60 years and older. There were 899 CHD events (32/100) and 326 stroke events (12/100). Using Cox proportional hazards, outcomes were modelled for the total cohort and for age groups 60-69, 70-79, and 80+ years. Total cholesterol, LDL cholesterol, serum apo-B, total cholesterol/high density lipoprotein (HDL) cholesterol and apo-B/apo-A1 were significant predictors of CHD in the total cohort, but significant only in the sub-group of 60-69 years. The respective hazard ratios (CI 95%) were 1.21 (1.09-1.35), 1.21 (1.09-1.35), 1.25 (1.13-1.39), 1.25 (1.14-1.37) and 1.21 (1.10-1.38). Similar findings were applicable with respect to ischaemic stroke in the age group of 60-69 years. Total cholesterol predicted CHD in men above a threshold value of 7.06 mmol/l and in women above 7.8 mmol/l, but with stroke the prediction was incremental. Other risk factors such as HDL cholesterol, triglycerides, lipoprotein(a), diabetes, hypertension and smoking predicted CHD, although only HDL and hypertension similarly predicted ischaemic stroke. The findings support a case for cholesterol testing in older subjects up to 70 years, in whom there is ancillary evidence of CHD and stroke prevention through treatment designed to reduce LDL cholesterol.

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.

Lipoprotein(a) and cognitive performances in an elderly white population: Cross-sectional and follow-up data

BACKGROUND AND PURPOSE

Elevated lipoprotein(a) [Lp(a)] serum levels have been associated with an increased risk of vascular diseases, and preliminary observations suggest that they are a risk factor for vascular dementia. The relationship between Lp(a) levels and cognitive performances in the general population has never been investigated. Our aim was to evaluate the effect of elevated Lp(a) levels on cognitive functions in the elderly.

METHODS

Cognitive performances were assessed by means of the Mini-Mental State Examination (MMSE), the Babcock Short Story, and the Matrix Test in a population sample of 435 white subjects aged 65 to 84 years who were evaluated at baseline and after 3 years. Lp(a) levels were determined by ELISA.

RESULTS

No statistically significant difference was found in neuropsychological test scores between subjects with and without elevated Lp(a) levels, although subjects with elevated Lp(a) levels had slightly better cognitive performances. This difference reached a statistical significance level only in a subscore of the Matrix Test (number of correct responses) when adjusted for age, sex, education, smoking, and history of stroke. At follow-up, no statistically significant difference was found in cognitive performances between subjects with and without elevated Lp(a) serum levels in either univariate or multivariate analyses. Subjects with and without elevated Lp(a) showed a similar decline rate during follow-up.

CONCLUSIONS

In this sample of elderly white subjects, elevated Lp(a) levels were not associated with poorer cognitive performances or with an increased rate of cognitive decline. Elevated Lp(a) levels do not appear to be a major determinant of cognitive impairment in the elderly.

Lipoprotein(a) serum levels and vascular diseases in an older Caucasian population cohort. Italian Longitudinal Study on Aging (ILSA)

OBJECTIVE

To investigate elevated lipoprotein(a) [Lp(a)] levels as a risk factor for stroke, myocardial infarction, angina, intermittent claudication, and combination of the above in a cohort of unselected older individuals.

DESIGN

Population cohort from one of the eight centers participating in the Italian Longitudinal Study on Aging (ILSA).

SETTING

General community.

PARTICIPANTS

A subsample of 446 subjects (M/F: 231/ 215, mean age: 74.5 +/- 5.7 years) of the original, randomly selected, population cohort of 704 individuals, 65 to 84 years of age, free-living or institutionalized in the Impruneta Municipality, area of Florence, Italy.

MEASUREMENTS

Conventional vascular risk factors and vascular diseases defined following a two-step procedure (screening phase and confirmation on positives) using standard and validated criteria. Lp(a) levels determined by an ELISA method.

RESULTS

No association was observed between elevated Lp(a) levels alone and any of the examined vascular diseases (stroke, myocardial infarction, angina, and intermittent claudication). In contrast, examining the interactions between elevated Lp(a) and conventional vascular risk factors, when elevated Lp(a) was combined with a history of smoking, a marked increase in the risk of vascular diseases combined (odds ratio [OR]: 4.12; 95% confidence interval [CI]: 1.27-13.40) was observed, much higher than that expected based on the additive effect of smoking and elevated Lp(a) alone.

CONCLUSIONS

With the cautions due to the cross-sectional design of the study and the limited statistical power, these results suggest a possible synergistic effect between elevated Lp(a) levels and other pro-atherogenic factors such as smoking on the risk of vascular diseases in older individuals.

Lipoprotein(a) associated with coronary artery disease in older women: age and gender analysis

BACKGROUND

Lipoprotein (a) has been associated with increased coronary artery disease (CAD) risk in men, but relatively little data exists in women. While age influences the cardiovascular risk associated with Lp(a) in men, little is known about this phenomenon in women. The impact of gender on Lp(a) has not been fully studied in an ongoing clinical practice.

METHODS AND RESULTS

Baseline Lp(a) values were measured in 918 CAD and 829 non-CAD patients (603 females, 1144 males) entering an outpatient prevention clinic. The age-specific association of elevated Lp(a) (> 30 mg/dl) with CAD was examined after adjustment for traditional risk factors. Lp(a) was a significant risk factor (OR = 1.9, CI, 1.4-2.6) in men and women (OR = 1.9, CI 1.3-2.9). In men age < or = 55 years the odds ratio for increased cardiovascular risk in high vs low Lp(a) was 2.5 (CI 1.6-3.9). In men < or = 55, CAD increased from 32 to 61% as Lp(a) progressively rose from < or = 5 to > or = 45 mg/dl (P value for trend < 0.001). No significant increase was observed in men > 55 years (OR = 1.3, CI 0.9-2.1). In women < or = 55 years, the risk of CAD increased from 22 to 35% (OR 1.6, CI 0.8-3.2), and increased from 38 to 63% in women > 55 (OR 2.1, CI 1.3-3.5). Further, of high-risk patients (men < or = 55 and women > 55 years) with an Lp(a) in the range of 20-44 mg/dl (third quartile), younger men showed a greater incidence of CAD (51%) than older women (43%). Both genders revealed substantial risk when the Lp(a) values were above 45 mg/dl. (OR = 3.7, CI = 2.0-6.8 in younger men; OR = 3.3, CI = 1.6-6.6 in older women).

CONCLUSIONS

In this cross sectional study of both men and women, elevated Lp(a) was associated with a significantly increased risk of CAD in men and women. While we corroborate previous reports on the lack of association in older men, the determination of an enhanced Lp(a)-related risk in older women was new and unanticipated. Further, in this population of high risk patients, substantial cardiovascular risk appeared to be represented by higher concentrations of Lp(a) in women than observed in men.

The relationship between cholesterol and stroke: implications for antihyperlipidaemic therapy in older patients

Various studies on the relationship between serum cholesterol level and the risk of stroke have been published recently. Subsequent reviews have extrapolated information on stroke from the clinical trials originally aimed at lowering cholesterol for the primary and secondary prevention of myocardial infarction (MI) in middle-aged patients. We have reviewed the epidemiological knowledge on the relationship between serum cholesterol levels and stroke, and also focused on possible reduction of the risk of stroke with hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitor treatment. Possible benefits from such therapy are particularly relevant for the elderly population which is at particularly high risk for stroke. The effects of serum cholesterol levels on the risk for haemorrhagic and ischaemic stroke have been evaluated. Indirect epidemiological evidence indicates that serum levels of total cholesterol and its subfractions are determinants of stroke, but their associations are relatively weak. When exploring the possible association of serum cholesterol levels with the increased risk of stroke with aging, we concluded that, as in younger adults, elevated total cholesterol and decreased high density lipoprotein-cholesterol levels predispose to ischaemic stroke in the elderly. The mechanism through which serum cholesterol levels increase stroke risk is based on its actions on the artery walls. Indirect evidence suggests that the reduction in the stroke risk with HMG-CoA reductase inhibitors is larger than would be expected with reduction of elevated serum cholesterol level alone. Therefore, antioxidant and endothelium-stabilising properties of HMG-CoA reductase inhibitors may contribute in reducing the risk of stroke in recipients. Lowering high serum cholesterol with HMG-CoA reductase inhibitors has been beneficial in the primary and secondary prevention of MI. No trials have specifically tested the effect of cholesterol lowering with HMG-CoA reductase inhibitors on stroke occurrence. High serum cholesterol levels are a risk factor for ischaemic stroke, although the risk imparted is lower than that for MI. Although the relative risk of stroke associated with elevated serum cholesterol levels is only moderate, its population attributable risk is high given the increase in the elderly population worldwide. The effect of cholesterol reduction with HMG-CoA reductase inhibitors on prevention of ischaemic stroke should be evaluated in prospective, randomised, placebo-controlled trials in the elderly. The tolerability of lipid-lowering drugs in the elderly and the cost effectiveness of primary prevention of stroke using lipid-lowering drugs also needs to be assessed in the elderly.

Phytoestrogens do not influence lipoprotein levels or endothelial function in healthy, postmenopausal women

Plant estrogen or phytoestrogens (PE) are increasingly consumed for the purposes of menopause symptom relief and prevention of cardiovascular and other diseases. The objective of this study was to evaluate the effects of PE on plasma lipids and lipoproteins and on endothelial function. Twenty healthy, postmenopausal women, 50 to 70 years old, and with evidence of endothelial dysfunction, were treated with a soybean PE tablet of 80 mg/day of isoflavones. Endothelial function was assessed noninvasively using brachial ultrasound. A double-blind, placebo-controlled, randomized crossover design was employed. After 3 weeks stabilization on a standard fat-reduced diet, subjects received PE or placebo for 8 weeks in random order, separated by a washout period of 8 weeks. Compared with placebo, there were no significant effects of PE on blood pressure and plasma lipid or lipoprotein concentrations. Flow-mediated endothelium-dependent dilation (FMD) in response to reactive hyperemia was not significantly changed by PE ingestion (3. 3 +/- 0.7% on placebo vs 4.1 +/- 0.7% on PE, p >0.4). Variation in FMD was not correlated with change in plasma isoflavone concentration (r = -0.09, p >0.7). Glyceryl trinitrate endothelium-independent dilation was not significantly changed with PE (15.9 +/- 1.3% vs 13.7 +/- 1.2%, p >0.1). These results fail to show a significant impact of medium-term supplementation with 80 mg/day of isoflavones on lipid and lipoprotein levels or on endothelial function in healthy, postmenopausal women.

Fasting plasma glucose in non-diabetic elderly women predicts increased all-causes mortality and coronary heart disease risk

AIM

To confirm the hypothesis that upper normal plasma glucose levels in non-diabetic subjects are independently predictive of mortality and cardiovascular disease (CVD).

METHODS

The study reports on 113 months' follow-up in a prospective study of CVD in the Australian elderly, The Dubbo Study. The cohort, first examined in 1988-89, consisted of 2805 men and women 60 years and older. Of the cohort, 2419 (86%) were defined as non-diabetic. The prediction of outcomes by quartile of fasting plasma glucose was examined in a Cox proportional hazards model, after linkage to hospital and death records.

RESULTS

All-causes mortality increased progressively across quartile of fasting plasma glucose in both sexes, reaching statistical significance only in women. Coronary heart disease (CHD) incidence increased similarly, the increases being proportionately greater in women. Ischaemic stroke did not show a consistent gradient with fasting plasma glucose. After adjustment for age and other risk factors, all-causes mortality, CHD and ischaemic stroke incidence were not significantly related to plasma glucose in men. In women, all-causes mortality and CHD incidence showed a significant gradient with glucose quartile. Hazard Ratio (95% confidence intervals) for death in glucose Quartile IV (5.3-6.0 mmol/L) was 1.49 (1.03-2.14) and for CHD incidence was 1.52 (1.08-2.15). Subjects in the upper quartiles of fasting plasma glucose showed a clustering of overweight, hypertension, elevated serum triglycerides, reduced high density lipoprotein cholesterol and excess of small dense low density lipoprotein, suggestive of the Insulin Resistance Syndrome.

CONCLUSION

Fasting plasma glucose levels in the upper normal range in non-diabetic elderly subjects appear to be associated with increased all-causes mortality and CHD, especially in women.

Lack of association of lipoprotein(a) levels with coronary calcium deposits in asymptomatic postmenopausal women

OBJECTIVES

This study sought to determine the relationship of lipoprotein(a) (Lp(a)) and other cardiac risk factors to coronary atherosclerosis as measured by calcification of coronary arteries in asymptomatic postmenopausal women.

BACKGROUND

Lipoprotein(a) is considered a risk factor for coronary heart disease. Coronary calcium deposition is believed to be a useful noninvasive marker of coronary atherosclerosis in women. However, to our knowledge, there are no reports of the relationship of Lp(a) to coronary calcium in postmenopausal women.

METHODS

In 178 asymptomatic postmenopausal women (64 +/- 8 years), we measured Lp(a) and other cardiac risk factors: age, hypertension, diabetes, low-density lipoprotein cholesterol, smoking status, body mass index, physical activity level and duration of hormone replacement therapy. Electron-beam computed tomography was done to measure coronary calcium (calcium score). We analyzed the relationship between calcium score and cardiac risk factors using multivariate analysis.

RESULTS

Although calcium score correlated with traditional risk factors of age, diabetes, hypertension and smoking, it did not correlate with Lp(a) in the asymptomatic postmenopausal women. Similar multivariate analyses were done in the subjects age >60 years and in the subjects with significant coronary calcium deposit (calcium score > or =50). These analyses also have failed to show an association of levels of Lp(a) with coronary calcium deposits.

CONCLUSIONS

We conclude that in asymptomatic postmenopausal women, Lp(a) levels do not correlate with coronary atherosclerosis as measured by coronary calcium deposits.

Relationship of physical activity and fitness to lipid and lipoprotein (a) in elderly subjects

PURPOSE

To determine, both by a cross-sectional and longitudinal study design, the relationship of maximal oxygen consumption (VO2max) and physical activity (PA) to blood lipids and lipoprotein(a) [Lp(a)] in a population of healthy and weight-stable elderly volunteers aged 66-84 yr.

METHODS

In a cross-sectional study in 52 subjects (23 men and 29 women), all independent variables (age, anthropometric, VO2max, and PA indices) were used in a multiple stepwise regression analysis to select variables influencing lipid and lipoprotein parameters. In a prospective nonintervention study, 38 subjects (17 men and 21 women) were reexamined after 6 months.

RESULTS

In a cross-sectional study, sports activity index contributed significantly to total cholesterol (TC), low density lipoprotein (LDL) cholesterol (LDL-C), TC/high density lipoprotein (HDL) cholesterol (HDL-C) ratio, and LDL-C/HDL-C ratio variance in men, whereas VO2max accounted for 23% variance of apolipoprotein A-I in women. In a prospective study, there was no indication that any measured variable was correlated with absolute or relative changes in PA indices in the total group or when analyzed by gender.

CONCLUSIONS

These data confirm that favorable relationship between PA/fitness and blood lipid profile is visible in elderly people but spontaneous changes in habitual PA are not a sufficient stimulus to alter serum lipid and lipoprotein levels in this population. Furthermore, there is no direct association between Lp(a) levels and PA, fitness, or body composition in the elderly men and women.

Lipoprotein(a): intrigues and insights

Lipoprotein(a) is an atherogenic, cholesterol ester-rich lipoprotein of unknown physiological function. The unusual species distribution of lipoprotein(a) and the extreme polymorphic nature of its distinguishing apolipoprotein component, apolipoprotein(a), have provided unique challenges for the investigation of its biochemistry, genetics, metabolism and atherogenicity. Some fundamental questions regarding this enigmatic lipoprotein have escaped elucidation, as will be highlighted in this review.

Family history of early cardiovascular disease in children with moderate to severe hypercholesterolemia: relationship to lipoprotein (a) and low-density lipoprotein cholesterol levels

Lipoprotein (a) (Lp(a)) is an established cardiovascular risk factor in adults. We sought to evaluate whether raised Lp(a) levels were predictive of a family history of early cardiovascular disease (CVD) in children already at increased risk for premature atherosclerosis because of elevated low-density lipoprotein (LDL) cholesterol levels. Lp(a) and serum lipid levels were measured in 69 children and offspring with established moderate to severe hypercholesterolemia (serum cholesterol > 170 mg/dL) who were aged 10.7 +/- 4.3 years (range 1.5 to 21 years) and had been referred to a pediatric lipid center. The children represented families with a positive (n = 27) or negative (n = 42) history for premature CVD (<55 years of age in parent or grandparent). In all children, Lp(a) levels ranged from 1 to 140 mg/dL, with a median of 29 mg/dL. Mean total cholesterol, LDL cholesterol, and high-density lipoprotein (HDL) cholesterol levels were 234 mg/dL, 166 mg/dL, and 45 mg/dL, respectively. There was no difference in median Lp(a) levels between the children with a positive family history and those with a negative family history (29.9 mg/dL vs 29.0 mg/dL, respectively). In contrast, children with a positive family history showed significantly higher LDL cholesterol levels (186 +/- 61 mg/dL vs 153 +/- 52 mg/dL, P = .02). Thus, in this group of hypercholesterolemic children, LDL cholesterol but not Lp(a) levels were associated with a family history of premature CVD. Further studies are needed to identify additional specific risk factors associated with the development of CVD in this population.

Plasma lipoprotein(a) is not a predictor for restenosis after elective high-pressure coronary stenting

BACKGROUND

Lipoprotein(a) is a risk factor for coronary artery disease. Although it has been implicated in restenosis after balloon angioplasty, its role in restenosis within coronary stents is unknown. The aim of the study was to assess the role of plasma lipoprotein(a) as a predictor for restenosis after elective coronary stenting.

METHODS AND RESULTS

Elective, high-pressure stenting of de novo lesions in native coronary arteries with Palmaz-Schatz stents was performed in 325 consecutive patients. Clinical, angiographic, and biochemical data were analyzed prospectively. Angiographic follow-up was performed at 6 months. Lipoprotein(a) levels were compared in patients with and without restenosis. Angiographic follow-up was obtained in 312 patients (96%); recurrence was observed in 67 patients (21.5%). No clinical or biochemical variable was associated with restenosis. Lipoprotein(a) level was 37.81+/-49. 01 mg/dL (median, 22 mg/dL; range, 3 to 262 mg/dL) in restenotic patients and 36.95+/-40.65 mg/dL (median, 22 mg/dL; range, 0 to 244 mg/dL) in nonrestenotic patients (P=NS). The correlations between percent diameter stenosis, minimum luminal diameter, and late loss at follow-up angiography and basal lipoprotein(a) plasma level after logarithmic transformation were 0.006, 0.002, and 0.0017, respectively. Multiple stents were associated with a higher incidence of restenosis (P=0.006), but biochemical data in these patients were similar to those treated with single stents.

CONCLUSIONS

The basal plasma level of lipoprotein(a) measured before the procedure is not a predictor for restenosis after elective high-pressure coronary stenting.

Risk factors for ischemic stroke: Dubbo Study of the elderly

BACKGROUND AND PURPOSE

One in 10 deaths in Australia is due to stroke. The predictors of ischemic stroke have not been well defined, although hypertension, atrial fibrillation, and previous stroke have been consistently reported. We report on 98 months' follow-up in a prospective study of cardiovascular disease in the Australian elderly, the Dubbo Study.

METHODS

The cohort, first examined in 1988, was composed of 2805 men and women 60 years and older. The prediction of ischemic stroke by potential risk factors was examined in a Cox proportional hazards model, after linkage to hospital and death records.

RESULTS

Three hundred six men and women manifested an ischemic stroke event (ICD-9-CM 433 to 437), and 95 subjects suffered a fatal stroke event. In the multivariate model, the significant independent predictors of stroke were advancing age, female sex (48% lower risk), being married (30% lower risk), prior history of stroke (227% higher risk), use of antihypertensive drugs (37% higher risk), belonging to the highest category of blood pressure reading (67% higher risk), presence of atrial fibrillation (58% higher risk), HDL cholesterol (36% lower risk for each 1-mmol/L increment), impaired peak expiratory flow (77% higher risk for tertile I than for tertile III), physical disability (59% higher risk), and depression score (41% higher risk for tertile III than for tertile I).

CONCLUSIONS

These findings suggest that morbidity and mortality associated with ischemic stroke can be predicted by various clinical indicators, some of which may be amenable to intervention. The matters of impaired peak expiratory flow, depression score, and ischemic stroke require further study.

Lipoprotein(a) and lipoprotein profile in healthy centenarians: a reappraisal of vascular risk factors

In this study we assessed whether widely accepted risk factors for atherosclerotic vascular diseases such as lipoprotein(a) [Lp(a)], a cholesterol-rich lipoprotein under strict genetical control, and other lipid parameters change with age. The variations of blood levels and the pathophysiological role of Lp(a) in old people, and particularly in the oldest old, are unknown. Accordingly, we measured Lp(a) levels as well as total, LDL, and HDL cholesterol (CT), and triglycerides (TG) in sera from 75 healthy centenarians, 114 randomly selected subjects under 65 years, 73 randomly selected elderly people, and 30 healthy selected elderly people. The results showed that Lp(a) serum levels did not vary by age group, including centenarians. Remarkably, one-quarter of the centenarians had high Lp(a) serum levels even though they never suffered from atherosclerosis-related diseases. At variance with young and aged people, centenarians with high Lp(a) serum levels also had high plasma concentrations of the proinflammatory cytokine IL-6, suggesting that genetic control of the Lp(a) serum level may attenuate with age and that environmental factors such as chronic subclinical inflammatory processes may play a role. We also showed that most centenarians are paradoxically characterized by low HDL-CT and relatively high TG levels, which together are considered to be strong risk factors for coronary heart disease. On the whole, these data support the hypothesis that a continuous and complex reshaping of lipid metabolism occurs in physiological aging, likely contributing to successful aging.

Elevated lipoprotein(a) levels and small apo(a) isoforms are compatible with longevity: evidence from a large population of French centenarians

Epidemiological studies have shown lipoprotein(a) (Lp(a)) to be an independent risk factor for cardiovascular disease. Lp(a) is a cholesterol-rich, low-density lipoprotein (LDL)-like particle to which a large glycoprotein, apolipoprotein(a) (apo(a)) is attached. Plasma Lp(a) levels are highly genetically determined and influenced to a minor degree by environmental factors. In an effort to determine whether Lp(a) might be associated with longevity, we have evaluated Lp(a) levels and apo(a) isoform sizes in a population of French centenarians (n = 109) compared to a control group (n = 227). The mean age of centenarians was 101.5 +/- 2.4 years while the control group was 39.4 +/- 7.2 years. Plasma levels of total cholesterol and triglyceride were within the normal range in both centenarian and control subjects. Lp(a) levels were higher in centenarians (both male and female) than in the normolipidemic control group (mean Lp(a) level = 0.33 +/- 0.42 and 0.22 +/- 0.27 mg/ml, respectively, P < 0.005). The distribution of apo(a) isoforms was significantly shifted towards small isoform size in the centenarian population as compared to the controls (54.4 and 41.4% of isoforms < or = 27 kringles (kr), respectively, P = 0.04). Nonetheless, the apo(a) size distribution in centenarians did not entirely explain the high Lp(a) levels observed in this population. Factors other than apo(a) size, and which may be either genetic or environmental in nature, appear to contribute to the elevated plasma Lp(a) levels of our centenarian population. We conclude therefore that high plasma Lp(a) levels are compatible with longevity.

Physical activity and cardiovascular health in the elderly

People over the age of 65 constitute a growing proportion of the world population both in western and in developing countries. A unique feature of this group is the high prevalence of cardiovascular diseases, which negatively affect its quality of life as well as its life expectancy. Among the interventions able to reduce the health burden of cardiovascular diseases is physical activity. The benefits of physical activity have been demonstrated both in healthy and chronically ill elderly subjects, while the risks have been found to be modest. Physicians should recommend moderate-intensity physical activity to sedentary older subjects, who are still the majority within the elderly population.

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

OBJECTIVES

This study sought to examine whether lipoprotein(a) levels predict coronary artery lumen changes in patients with symptomatic coronary artery disease (CAD) and normal to moderate hypercholesterolemia.

BACKGROUND

Recent conflicting reports have confirmed or refuted the association of lipoprotein(a) with clinical events or angiographically verified disease progression.

METHODS

The association between serum lipoprotein(a) and changes in coronary artery lumen was studied in 704 men entered into the Regression Growth Evaluation Statin Study (REGRESS), a double-blind, placebo-controlled, quantitative angiographic study that assessed the effect of 2 years of pravastatin treatment. The primary end points were changes in average mean segment diameter (MSD) and average minimal obstruction diameter (MOD). Pravastatin- and placebo-treated patients were classified as having progressing, regressing or stable CAD, and median lipoprotein(a) concentrations were compared. Bivariate and multivariate regression analyses were performed in the overall patient group and in high risk subgroups.

RESULTS

Pravastatin treatment did not affect serum apolipoprotein(a) levels. Median in-trial (sampled at 24 months) apolipoprotein(a) levels for regressing, stable and progressing CAD were, respectively, 130, 162 and 251 U/liter in placebo-treated patients and 143, 224 and 306 U/liter in pravastatin-treated patients. Predictors of MSD and MOD changes were baseline MSD and MOD, in-trial apolipoprotein(a), in-trial high density lipoprotein (HDL) cholesterol and baseline use of long-acting nitrates. The multivariate models predicted 14% of MSD changes and 12% of MOD changes; apolipoprotein(a) predicted only 2.6% and 4.8%, respectively. However, in patients with in-trial HDL cholesterol levels <0.7 mmol/liter, apolipoprotein(a) predicted up to 37% of the arteriographic changes.

CONCLUSIONS

Serum lipoprotein(a) levels predict coronary artery lumen changes in normal to moderately hypercholesterolemic white men with CAD; its atherogenicity is marked in the presence of concomitant hypoalphalipoproteinemia.

Lipoprotein(a) interactions with lipid and nonlipid risk factors in early familial coronary artery disease

An interaction between high plasma lipoprotein(a) [Lp(a)], unfavorable plasma lipids, and other risk factors may lead to very high risk for premature CAD. Plasma Lp(a), lipids, and other coronary risk factors were examined in 170 cases with early familial CAD and 165 control subjects to test this hypothesis. In univariate analysis, relative odds for CAD were 2.95 (P < .001) for plasma Lp(a) above 40 mg/dL. Nearly all the risk associated with elevated Lp(a) was found to be restricted to persons with historically elevated plasma total cholesterol (6.72 mmol/L [260 mg/dL] or higher) or with a total/HDL cholesterol ratio > 5.8. Nonlipid risk factors were also found to at least multiply the risk associated with Lp(a). When Lp(a) was over 40 mg/dL and plasma total/HDL cholesterol > 5.8, relative odds for CAD were 25 (P = .0001) in multiple logistic regression. If two or more nonlipid risk factors were also present (including hypertension, diabetes, cigarette smoking, high total homocysteine, or low serum bilirubin), relative odds were 122 (P < 1 x 10(-12)). The ability of nonlipid risk factors to increase risk associated with Lp(a) was dependent on at least a mildly elevated total/HDL cholesterol ratio. In conclusion, high Lp(a) was found to greatly increase risk only if the total/HDL cholesterol ratio was at least mildly elevated, an effect exaggerated by other risk factors. Aggressive lipid lowering in those with elevated Lp(a) therefore appears indicated.

The solution phase interaction between apolipoprotein(a) and plasminogen inhibits the binding of plasminogen to a plasmin-modified fibrinogen surface

In the present study, we assessed the binding of recombinant forms of apolipoprotein(a) [r-apo(a)] to plasminogen. Apo(a)-plasminogen interactions were demonstrated to be lysine-dependent, as they were abolished by the addition of epsilon-aminocaproic acid. Binding of r-apo(a) and plasma-derived Lp(a) to Glu-plasminogen was assessed in solution using a mutant form of recombinant plasminogen [Plg(S741C)] labeled at the active site with 5'-(iodoacetamido)fluorescein. High-affinity binding of apo(a) to plasminogen was observed with the 17-kringle r-apo(a) (Kd = 20.1 +/- 3.3 nM) as well as with plasma-derived Lp(a) (Kd = 5.58 +/- 0.08 nM). Binding studies using various truncated and mutant forms of r-apo(a) demonstrated that sequences within apo(a) kringle IV types 2-9 and the strong lysine binding site (LBS) in apo(a) kringle IV type 10 are not required for high-affinity binding to plasminogen. In all cases, the binding stoichiometry for the apo(a)-plasminogen interaction was determined to be 1:1. Binding data obtained using a 17-kringle r-apo(a) derivative lacking the protease-like domain (17KDeltaP; Kd = 3158 +/- 138 nM) indicate that sequences within the protease-like domain of apo(a) mediate its interaction with LBS in plasminogen. We determined that r-apo(a) and plasminogen bind to distinct sites on plasmin-modified fibrinogen with the concentration of plasminogen binding sites exceeding the concentration of r-apo(a) sites by a factor of 10. Furthermore, r-apo(a) is capable of inhibiting the binding of plasminogen to plasmin-modified fibrinogen surfaces, an effect which we show is attributable to the formation of a solution phase apo(a)/plasminogen complex which exhibits a greatly reduced affinity for plasminogen binding sites on plasmin-modified fibrinogen. The results of this study provide new insights into the mechanism by which apo(a) and Lp(a) may inhibit fibrinolysis, thus contributing to the atherothrombotic risk associated with this lipoprotein.

Apolipoprotein(a) isoforms and coronary heart disease in men: a nested case-control study

The objective of the present study was to examine the possible associations between low molecular weight (LMW) apolipoprotein(a) (apo(a)) isoforms (F,B,S1,S2) and coronary heart disease (CHD). We conducted a nested case-control (prospective) study of five cohorts of white men: The 1936 cohort (baseline 1976, n = 548) and four cohorts from MONICA I born in 1923 (n = 463), 1933 (n = 491), 1943 (n = 504) and 1953 (n = 448) studied at baseline in 1983. At follow up in 1991, 52 subjects had developed a first myocardial infarction and 22 had been hospitalized with angina pectoris. Plasma samples obtained at baseline were stored frozen until 1993-94, when case samples (n = 74) were analyzed together with samples from matched (disease free) controls (n = 190). In a statistical model (conditional logistic regression) including all age groups, cholesterol (or apo B) level (P < 0.01), systolic blood pressure (P = 0.05) and smoking (P = 0.02) predicted CHD. In the statistical model Lp(a) interacted significantly with age (OR = 5.7; 95% CI: 1.4-23.6; P = 0.016), and high Lp(a) (over 45 mg/dl) was associated with significantly increased risk in subjects under 60 years (OR = 3.82; 95% CI: 1.47-9.96), but not in older men (OR = 0.67; 95% CI: 0.235-1.89). Therefore, we studied the impact of Lp(a)/apo(a) and other variables in subjects who had been under 60 years when they became cases. Among the younger subjects the presence of LMW apo(a) isoforms significantly predicted the development of CHD (OR = 3.83; 95% CI: 1.18-12.4). The increased risk pertained to high Lp(a) (above versus below 45 mg/dl: OR = 3.68; 95% CI: 1.03-13.10), and to Lp(a) concentrations when entered into the model as a continuous variable (P = 0.04). Cholesterol or apo B (P < 0.01), smoking (P = 0.02), systolic blood pressure (P = 0.05) and low alcohol consumption (under nine drinks/week) (P = 0.04) were also significant predictors of CHD. We conclude that LMW apo(a) isoforms are significantly associated with increased risk of CHD in men under 60 years.

Lipoprotein (a) distribution in a Nigerian population

OBJECTIVES

To determine the distribution and determinants of lipoprotein (a) (Lp(a)) concentration among Nigerians.

METHODS

Subjects were recruited from civil servants living in Benin City, Nigeria. The height and weight of the individuals were measured and their use of alcohol and tobacco estimated by questionnaire. Laboratory analyses of blood samples involved Lp(a), total cholesterol (TC), high-density lipoprotein (HDLc), HDL2c, HDL3c, triglyceride (TG) and insulin.

RESULTS

The analyses indicate that the Lp(a) concentrations are elevated among Nigerian populations and more skewed towards high levels than is observed for caucasian and oriental groups. The median levels for Lp(a) were 24.0 mg dl-1 and 19.0 mg dl-1 for women and men, respectively. This difference was significant (P < 0.05) but after stratifying by age, only the 45-54 year-old group of women (30.1 mg dl-1) had significantly higher (p < 0.001) median concentrations of Lp(a) than men (18.4 mg dl-1). Age, 20-64, had no influence on Lp(a) levels in men but in women Lp(a) concentrations increased significantly with age (p < 0.05). Among males alcohol consumption, smoking and body mass index (BMI) were not related to Lp(a) concentrations but a significant effect (p < 0.05) was noted for waist-hip ratio (WHR). Among females no relationship was observed between Lp(a) levels and alcohol consumption, BMI and WHR. All serum lipids measured (TC, HDLc, HDL2c, HDL3c, low-density lipoprotein (LDLc), and TG) were correlated with Lp(a) concentrations among men. A significant association with TC and LDLc remained after correcting for Lp(a) cholesterol. Among women, the Lp(a) levels were associated with TC, HDLc, HDL3c, and LDLc but not with HDL2c, and TG. The correlations with TC and LDLc were not significant after correcting for Lp(a) cholesterol. Insulin did not correlate with Lp(a) levels in either men or women.

CONCLUSIONS

Lp(a) concentrations are high in Nigerians, particularly among women, and the association between the Lp(a) concentrations and other lipoproteins is stronger than in white populations.

Lipoprotein(a) as a determinant of coronary heart disease in young women

BACKGROUND

Lipoprotein(a) [Lp(a)] appears to be a risk factor for coronary heart disease (CHD) in men. The role of Lp(a) in women, however, is less clear.

METHODS AND RESULTS

We examined the ability of Lp(a) to predict CHD in a population-based case-control study of women 65 years of age or younger who lived in the greater Stockholm area. Subjects were all patients hospitalized for an acute CHD event between February 1991 and February 1994. Control subjects were randomly selected from the city census and were matched to patients by age and catchment area. Lp(a) was measured 3 months after hospitalization by use of an immunoturbidometric method (Incstar) calibrated to the Northwest Lipid Research Laboratories (coefficient of variation was < 9%). Of the 292 consecutive patients, 110 (37%) were hospitalized for an acute myocardial infarction, and 182 were hospitalized (63%) for angina pectoris. The mean age for both patients and control subjects was 56 +/- 7 years. Of participants, 74 patients (25%) and 84 control subjects (29%) were premenopausal. The distributions of Lp(a) were highly skewed in both patients and control subjects, with a range from 0.001 to 1.14 g/L. Age-adjusted odds ratio for CHD in the highest versus the lowest quartile of Lp(a) was 2.3 (95% confidence interval [CI], 1.4 to 3.7). After adjustment for age, smoking, education, body mass index, systolic blood pressure, total cholesterol, triglycerides, and HDL, the odds ratio was 2.9 (95% CI, 1.6 to 5.0). The odds ratios were similar when myocardial infarction and angina patients were compared with their respective control subjects. The odds ratios were 5.1 (95% CI, 1.4 to 18.4) and 2.4 (95% CI, 1.3 to 4.5) in premenopausal and postmenopausal women, respectively.

CONCLUSIONS

These results suggest that Lp(a) is a determinant of CHD in both premenopausal and postmenopausal women.

Risk of primary and recurrent acute myocardial infarction from lipoprotein(a) in men and women

OBJECTIVES

This study sought to examine whether lipoprotein(a) concentrations were risk factors for a first acute and recurrent myocardial infarction.

BACKGROUND

There is conflicting evidence concerning the risk of acute myocardial infarction from lipoprotein(a). No studies have examined the risk of recurrent acute myocardial infarction from lipoprotein(a), and few have addressed the risk in women.

METHODS

This was a population-based case-control study of 893 men and women 35 to 69 years old participating in the World Health Organization Monitoring Trends and Determinants in Cardiovascular Disease (MONICA) Project in Newcastle, Australia in 1993 to 1994. Case and control patients were classified into those with and without a previous myocardial infarction, and median lipoprotein(a) concentrations were compared after adjusting for other variables. Quintiles of lipoprotein(a) concentration were also examined.

RESULTS

Compared with control subjects without a previous myocardial infarction, median lipoprotein(a) concentrations increased from case patients with a first myocardial infarction (15 mg/liter higher, 95% confidence interval [CI] -36 to 60) to control patients with a previous myocardial infarction (159 mg/ liter higher, 95% CI 40 to 278) and case patients with a previous myocardial infarction (60 mg/liter higher, 95% CI -16 to 136, p < 0.01, test for trend). Women had significantly higher lipoprotein(a) concentrations than men (median 71 mg/liter higher, 95% CI 23 to 118). The highest quintile of lipoprotein(a) (>550 mg/liter) was a significant risk factor for a first acute myocardial infarction (odds ratio [OR] 1.77, 95% CI 1.03 to 3.03); but in those with a previous myocardial infarction, the highest quintile was not associated with recurrent myocardial infarction (OR 0.84, 95% CI 0.30 to 2.37).

CONCLUSIONS

High lipoprotein(a) concentrations may be a marker of vascular or tissue injury or may be associated with other genetic or environmental factors that cause acute myocardial infarction. Currently, lipoprotein(a) measurement cannot be recommended for assessment of risk for acute myocardial infarction.

Alcohol intake and survival in the elderly: a 77 month follow-up in the Dubbo study

BACKGROUND

A prospective study in non-institutionalised Australian elderly aged 60 years and over commenced in Dubbo, NSW in 1988.

AIM

To examine the relationship between all-causes mortality and alcohol intake.

METHODS

The data were derived from a community-based sample comprising 1236 men and 1569 women followed for a median period of 77 months. Regular alcohol intake was reported by 78% of men and 52% of women. Eighty-seven per cent of men and 44% of women primarily drank beer.

RESULTS

Death occurred in 305 men and 236 women, 34% and 39% respectively from coronary heart disease (CHD). In a proportional hazards model, the hazard ratio (HR) for all-causes mortality in male drinkers, compared with abstainers, was 0.75 at one-seven drinks/week, 0.76 at eight-14 drinks/week, 0.69 at 15-28 drinks/week and 0.49 at > 28 drinks/week (p < 0.04), an inverse relationship. In female drinkers, HR was 0.78 at one-seven drinks/week, 0.49 at eight-14 drinks/week (p < 0.04) and 0.62 at 15-28 drinks/weeks, potentially a U shaped relationship. The effect on all-causes mortality could not be attributed to a differential effect of beer versus wine/spirit intake. Although the mortality rate was lower in those taking any alcohol compared with abstainers, those taking any alcohol exhibited an increased proportion of deaths due to cancer at the expense of a reduced proportion of CHD and stroke deaths.

CONCLUSIONS

Alcohol intake in the Dubbo elderly appears to be independently associated with a significant increase in life expectancy. Mechanisms underlying the effect may emerge at a longer interval of follow-up.

Lack of increased coronary atherosclerotic risk due to elevated lipoprotein(a) in women > or = 55 years of age

BACKGROUND

Numerous studies have indicated that there is an association between lipoprotein(a) [Lp(a)] and coronary artery disease (CAD) in middle-aged men; however, few studies have addressed this issue in women or the elderly.

METHODS AND RESULTS

Serum Lp(a) concentrations were determined in 354 women and 706 men with or without angiographically defined CAD (one or more coronary arteries with narrowing of > or = 75%). The age-specific impact of elevated Lp(a) (> or = 30 mg/dL) on CAD was examined in each sex. In the younger age group (< 55 years old), elevated Lp(a) was independently associated with CAD in both sexes (adjusted odds ratio [OR]: women, 6.90, P < .01; men, 2.63, P < .05). The age-specific ORs declined with age, and elevated Lp(a) no longer conferred an increased CAD risk in either elderly men or women > or = 65 years old. In the age group of 55 to 64 years, elevated Lp(a) was positively associated with CAD for men (adjusted OR: 2.45, P < .05) but not for women (adjusted OR: 0.56, P = NS).

CONCLUSIONS

For both sexes, elevated Lp(a) appears to be an independent risk factor for premature CAD and the importance of Lp(a) appears to decrease with age. However, for women, the risk estimate of Lp(a) began to decline at an age approximately 10 years younger than for men. These data suggest that not only age- but also sex-specific factors such as menstrual status may interact with the association between Lp(a) and CAD.

Lipoprotein(a) and its correlates in Japanese and U.S. population samples

To examine whether serum levels of lipoprotein(a) [Lp(a)], a potential coronary risk factor, are higher in Caucasian-Americans than in Japanese, a circumstance that would correspond to the higher mortality from coronary heart disease in the United States than in Japan, we analyzed serum Lp(a) levels in 300 nonsmoking men and women aged 47-69 years. Participants were drawn from two population-based samples: rural Japanese living in Akita and Caucasians living in Minneapolis-St. Paul, MN. Geometric mean and median serum Lp(a) concentrations were higher (P < 0.05) in Japanese than in Caucasians for both men (difference in geometric mean = 3.2 mg/dL) and women (difference = 5.3 mg/dL). There was however, no racial difference in the proportion of elevated Lp(a) concentrations (i.e., > or = 30 mg/dL) in either sex. Alcohol intake was inversely correlated with Lp(a) levels in Japanese men, who had a high average alcohol intake, but not in other sex and racial groups. Serum Lp(a) was nonsignificantly but consistently correlated with plasma fibrinogen and LDL-cholesterol for all sex and racial groups. With adjustment for alcohol intake, LDL-cholesterol, and plasma fibrinogen, the Japanese-Caucasian difference in geometric mean Lp(a) values was even larger for men and was not changed for women. Results of the present study do not support the hypothesis that racial differences in Lp(a) concentrations contribute to the higher mortality rate from coronary heart disease in the United States than in Japan.

The effect of endurance training on lipoprotein(a) [Lp(a)] levels in middle-aged males

Serum lipoprotein(a) [Lp(a)] levels were measured before and after a 12-wk program of moderate-intensity endurance training. The training program consisted of walking and/or jogging, at least three sessions.wk-1 of at least 30 min duration, at an intensity producing 60-85% HRmax reserve. Twenty-eight previously sedentary middle-aged Caucasian males matched for age, body mass, and body mass index (BMI) were randomly allocated to either an exercise (N = 17, mean age +/- SEM = 51.57 +/- 1.25 yr) or a control (N = 11, mean age +/- SEM = 50.0 +/- 1.15 yr) group. Pre- and post-training median Lp(a) levels, measured by immunoturbidimetric analysis, were not significantly different in either the exercise (pre 13.0, post 15.0 mg.dl-1) or the control subjects (pre 14.0, post 12.0 mg.dl-1) (P > 0.05). Kendall Rank correlation analysis revealed no significant relationship between the level of Lp(a) and any other variable in either group before or after training. In the exercisers, a significant increase (P < 0.05) was recorded in the estimated mean VO2max (pre 33.39 +/- 1.70, post 37.7 +/- 1.75 ml.kg-1 min-1). These data indicate that the level of Lp(a) was not influenced by a 12-wk program of moderate-intensity endurance training, and are consistent with previous reports suggesting that Lp(a) level is not altered by lifestyle factors.

Lipoprotein(a) and peripheral atherosclerosis in older adults

As part of an ancillary study to the Systolic Hypertension in the Elderly Program, carotid and lower extremity arterial disease (LEAD) were evaluated in 369 subjects, 186 with a systolic blood pressure (SBP) > or = 160 mmHg, and 183 with SBP < 160 mmHg. Both groups had a diastolic blood pressure (DBP) < 90 mmHg. Internal carotid stenosis was identified by Doppler and LEAD was assessed using the ankle to arm systolic blood pressure ratio, commonly called the ankle/arm index (AAI). Lp(a) values were obtained from frozen sera and values > or = 20 mg/dl were considered elevated. Rates of carotid stenosis were 24% among those with an Lp(a) > or = 20 mg/dl and 14% among those with an Lp(a) level < 20 mg/dl (P = 0.020). The relationship between Lp(a) and LEAD was even stronger. Those with an Lp(a) > or = 20 mg/dl had a 36% prevalence of a low AAI vs 14% among those with a Lp(a) level < 20 mg/dl (P < 0.001). Lp(a) values were also associated with the severity of LEAD. Controlling for other risk factors did not reduce the association between either LEAD or carotid stenosis and an Lp(a) > or = 20 mg/dl. Thus, Lp(a) appears to be independently associated with peripheral atherosclerosis in older adults, both men and women. The relationship is particularly strong for atherosclerotic disease of the lower extremities.

Coronary heart disease risk factors in older persons

In most Western nations, coronary heart disease (CHD) is the leading cause of death and one of the most important causes of physical disability in persons over 65 years of age. The importance of traditional CHD risk factors has been well documented in middle-aged populations, whereas their role in older populations is still under debate. This paper reviews the epidemiologic evidence from observational studies and randomized clinical trials that established risk factors for CHD predict level of risk of CHD, and identify high risk individuals among older men and women. Hypertension and cigarette smoking have been clearly associated with an increased risk of CHD events, and their modification has been proven to be highly effective in the primary and secondary prevention of CHD in older persons. For other highly prevalent risk factors, such as lipid abnormalities, obesity and physical inactivity, evidence of an independent association with CHD risk has been demonstrated by the majority of observational studies. However, definitive proof from controlled clinical trials of the beneficial effects of their modification is still lacking in the older population. The role of estrogen replacement therapy in the primary and secondary prevention of CHD in old women is still an open question. In evaluating the impact of these risk factors in older persons, elements such as comorbidity, frailty, and age-related changes in risk profile should also be taken into consideration. Given the complexity of the relationship between risk factors and multiple disease statuses, other important outcomes, such as osteoporosis, cancer, falls and physical disability, should be considered when evaluating the risks and benefits of risk factor modifications in older persons.