Paolo Rubba

Low Circulating Folate and Vitamin B6 Concentrations Risk Factors for Stroke, Peripheral Vascular Disease, and Coronary Artery Disease

BACKGROUND A high plasma homocysteine concentration is a risk factor for atherosclerosis, and circulating concentrations of homocysteine are related to levels of folate and vitamin B6. This study was performed to explore the interrelationships between homocysteine, B vitamins, and vascular diseases and to evaluate the role of these vitamins as risk factors for atherosclerosis. METHODS In a multicenter case-control study in Europe, 750 patients with documented vascular disease and 800 control subjects frequency-matched for age and sex were compared. Plasma levels of total homocysteine (before and after methionine loading) were determined, as were those of red cell folate, vitamin B12, and vitamin B6. RESULTS In a conditional logistic regression model, homocysteine concentrations greater than the 80th percentile for control subjects either fasting (12.1 micromol/L) or after a methionine load (38.0 micromol/L) were associated with an elevated risk of vascular disease independent of all traditional risk factors. In addition, concentrations of red cell folate below the lowest 10th percentile (<513 nmol/L) and concentrations of vitamin B6 below the lowest 20th percentile (<23.3 nmol/L) for control subjects were also associated with increased risk. This risk was independent of conventional risk factors and for folate was explained in part by increased homocysteine levels. In contrast, the relationship between vitamin B6 and atherosclerosis was independent of homocysteine levels both before and after methionine loading. CONCLUSIONS Lower levels of folate and vitamin B6 confer an increased risk of atherosclerosis. Clinical trials are now required to evaluate the effect of treatment with these vitamins in the primary and secondary prevention of vascular diseases.

Pravastatin reduces carotid intima-media thickness progression in an asymptomatic hypercholesterolemic Mediterranean population: The Carotid Atherosclerosis Italian Ultrasound Study

PURPOSE The Carotid Atherosclerosis Italian Ultrasound Study (CAIUS) was performed to test the effects of lipid lowering on the progression of carotid intima-media thickness (IMT) in 305 asymptomatic patients from a Mediterranean country. PATIENTS AND METHODS Eligibility included hypercholesterolemia (baseline means: low-density lipoprotein [LDL] = 4.68 mmol/L, high-density lipoprotein [HDL] = 1.37 mmol/L), and at least one 1.3 < IMT < 3.5 mm in the carotid arteries. Patients (mean age 55 years, 53% male) were assigned to pravastatin (40 mg/day, n = 151) or placebo (n not equal to 154). Ultrasound imaging was used to quantify IMT at baseline, and semiannually thereafter for up to 3 years. The mean of the 12 maximum IMTs (MMaxIMT), was calculated for each patient visit, and used to determine each patients longitudinal progression slope. The intention-to-treat group difference in the MMaxIMT progression was chosen a priori as the primary end point. RESULTS Five serious cardiovascular events (1 fatal myocardial infarction), and 7 drop-outs for cancer were registered. In the pravastatin group, LDL decreased -0.22 after 3 months versus -0.01 in the placebo group, and remained substantially unchanged afterward (-0.23 versus +0.01 at 36 months, respectively). Progression of the MMaxIMT was 0.009 +/- 0.0027 versus -0.0043 +/- 0.0028 mm/year (mean +/- SE, P < 0.0007) in the placebo and pravastatin groups, respectively. IMT progression slopes diverged after 6 months of treatment. CONCLUSIONS Pravastatin stops the progression of carotid IMT in asymptomatic, moderately hypercholesterolemic men and women. This finding extends the beneficial effects of cholesterol lowering to the primary prevention of atherosclerosis in a population with relatively low cardiovascular event rates, and suggests that this benefit is mediated by specific morphological effects on early stages of plaque development.

Association of Obesity and Central Fat Distribution With Carotid Artery Wall Thickening in Middle-Aged Women

Background and Purpose— The association between obesity and atherosclerotic disease is controversial. In the present analysis, we evaluated whether common carotid intima-media thickness (IMT) and area, 2 markers of preclinical atherosclerosis, were increased in obese subjects. Methods— More than 5000 middle-aged women (n=5062; age, 30 to 69 years) living in the area of Naples, Southern Italy, were recruited for a prospective, currently ongoing study on the etiology of cardiovascular disease and cancer in the female population (the Progetto ATENA study). A subsample of 310 participants underwent high-resolution B-mode ultrasound examination, and the IMTs, intima-media areas, and lumen diameters of common carotid arteries were measured with a semiautomated computerized program. Subjects were divided into 3 groups on the basis of the recently published obesity guidelines for body mass index (BMI), a marker of general obesity, and tertiles of waist-to-hip ratio (WHR), a marker of regional obesity. Results— Women with a BMI ≥30 kg/m2 showed higher systolic and diastolic blood pressures, triglycerides, and fasting glucose and insulin, as well as lower high-density lipoprotein concentrations, than subjects with lower BMI. A gradual increase in common carotid IMT and intima-media area was observed when lean women (0.94±0.01 mm and 19.8±0.5 mm2, respectively) were compared with overweight (0.98±0.01 mm and 21.0±0.4 mm2) and obese (1.02±0.02 mm and 22.6±0.8 mm2, P <0.005 for linear trend) individuals. Similarly, women in the highest tertile of WHR (>0.85) had adverse risk factor profiles and thicker carotid intima-media complex than those in the first 2 tertiles (P <0.01 and P <0.05 for IMT and intima-media area, respectively). In multivariate analyses, BMI and WHR were significant predictors of carotid wall thickness, independently of other traditional and nontraditional cardiovascular risk factors (age, blood pressure, lipid abnormalities, fasting insulin). Conclusions— The present results indicate a graded and independent association between general and abdominal obesity—reflected by high BMI and WHR—and carotid artery wall thickening in a population of middle-aged women.

Baseline reproducibility of B-mode ultrasonic measurement of carotid artery intima-media thickness: the European Lacidipine Study on Atherosclerosis (ELSA).

Background and objective The European Lacidipine Study of Atherosclerosis (ELSA) is a prospective, randomized, double-blind, multi-national interventional trial to determine the effect of four-year treatment using the calcium antagonist lacidipine versus the β-blocker atenolol on the progression of carotid atherosclerosis in 2259 asymptomatic hypertensive patients. B-mode ultrasound is used to measure the primary and secondary endpoints including the mean maximum intima-media thickness (IMT) of the carotid bifurcations and the common carotid arteries (CBMmax), the mean maximum IMT of 12 standard carotid sites (Mmax) and the overall maximum IMT (Tmax). This paper reports the cross-sectional reproducibility of ultrasound measurements at baseline. Method To evaluate measurement reliability, each patient is scanned twice at baseline and again at four annual visits, with 80% of the replicate scans performed by the same sonographer and 20% by a different sonographer; 50% of the replicate scans are read by the same reader and the other 50% by different readers. Results The overall coefficient of reliability (R) was 0.859 for CBMmax, 0.872 for Mmax and 0.794 for Tmax. The reliability for CBMmax was stable during the 13/4-year baseline period (R = 0.848 to 0.953) and was uniform among the 23 field centres (R = 0.798 to 0.926). Intra-and inter-reader reliability were 0.915 and 0.872 respectively, and intra-sonographer reliability was 0.866. Conclusion The results demonstrate that by implementing standardized protocols and strict quality control procedures, highly reliable ultrasonic measurements of carotid artery IMT can be achieved in large multi-national trials.

Different effects of antihypertensive regimens based on fosinopril or hydrochlorothiazide with or without lipid lowering by pravastatin on progression of asymptomatic carotid atherosclerosis: Principal results of PHYLLIS - A randomized double-blind trial

Background and Purpose— The Plaque Hypertension Lipid-Lowering Italian Study (PHYLLIS) tested whether (1) the angiotensin-converting enzyme (ACE) inhibitor fosinopril (20 mg per day) was more effective on carotid atherosclerosis progression than the diuretic hydrochlorothiazide (25 mg per day), (2) pravastatin (40 mg per day) was more effective than placebo when added to either hydrochlorothiazide or fosinopril, and (3) there were additive effects of ACE inhibitor and lipid-lowering therapies. Methods— A total of 508 hypertensive, hypercholesterolemic patients with asymptomatic carotid atherosclerosis were randomized to: (A) hydrochlorothiazide; (B) fosinopril; (C) hydrochlorothiazide plus pravastatin; and (D) fosinopril plus pravastatin, and followed up blindly for 2.6 years. B-Mode carotid scans were performed yearly by certified sonographers in 13 hospitals and read centrally. Corrections for drift were calculated from readings repeated at study end. Primary outcome was change in mean maximum intima-media thickness of far and near walls of common carotids and bifurcations bilaterally (CBMmax). Results— CBMmax significantly progressed (0.010±0.004 mm per year; P=0.01) in group A (hydrochlorothiazide alone) but not in groups B, C, and D. CBMmax changes in groups B, C, and D were significantly different from changes in group A. Changes in group A were concentrated at the bifurcations. “Clinic” and “ambulatory” blood pressure reductions were not significantly different between groups, but total and low-density lipoprotein cholesterol decreased by ≈1 mmol/L in groups C and D. Conclusions— Progression of carotid atherosclerosis occurred with hydrochlorothiazide but not with fosinopril. Progression could also be avoided by associating pravastatin with hydrochlorothiazide.

Systolic and pulse blood pressures (but not diastolic blood pressure and serum cholesterol) are associated with alterations in carotid intima-media thickness in the moderately hypercholesterolaemic hypertensive patients of the Plaque Hypertension Lipid Lowering Italian Study

Objective The Plaque Hypertension Lipid Lowering Italian Study (PHYLLIS), is the first study in patients with hypertension (diastolic blood pressure (DBP) 95–115 mmHg; systolic blood pressure (SBP) 150–210 mmHg), moderate hypercholesterolaemia (LDL-cholesterol 4.14–5.17 mmol/l (160–200 mg/dl) and initial carotid artery alterations (maximum intima–media thickness (IMT) Tmax ⩾ 1.3 mm). The primary objective of PHYLLIS is investigating whether in these patients administration of an angiotensin converting enzyme inhibitor, fosinopril, and a statin, pravastatin, is more effective than administration of a diuretic and a lipid-lowering diet in retarding or regressing alterations in carotid IMT. While the study is in progress, baseline data are here reported to clarify the association of various risk factors with carotid IMT in these medium–high risk hypertensive patients. Methods Patients numbering 508 have been randomized to PHYLLIS by 13 peripheral units, in Italy. Age was (mean ± SD) 58.4 ± 6.7 years, males were 40.2%, current smokers 16.5%, means ± SD of serum total, low-density lipoprotein (LDL), high-density lipoprotein (HDL) cholesterol and triglycerides concentrations were 6.79 ± 0.67, 4.69 ± 0.51, 1.37 ± 0.38, 1.59 ± 0.64 mmol/l (262.4 ± 25.8, 181.3 ± 19.8, 53.0 ± 14.6, 141.0 ± 56.7 mg/dl). Means ± SD of clinic sitting SBP/DBP were 159.8 ± 9.0/98.3 ± 4.2 mmHg. 483 of the 508 patients also had 24 h ambulatory BP monitoring, edited and read at a centralized unit (mean ± SD 24 h SBP/DBP averages 136.3 ± 14.1/84.0 ± 10.0 mmHg). Quantitative B-mode ultrasound (Biosound 2000 II 5A, Biosound, Indianapolis, Indiana, USA) recordings of carotid arteries were taken by certified sonographers in the peripheral units and tracings were all read at a central unit. CBMmax (mean IMT of eight sites at common carotids and bifurcations) was 1.21 ± 0.17; Mmax (mean of 12 sites also including internal carotids) 1.16 ± 0.17, and Tmax (single maximum) 1.85 ± 0.48 mm. Results Ambulatory SBP and pulse pressure (PP) (24 h, daytime, night-time averages) and their variability indices (24 h SD) were always significantly correlated with CBMmax and Mmax (P 0.01–0.001), and the correlations remained significant after adjustment for age, gender and smoking. No measurement of DBP was ever associated with any IMT measurement. Likewise, no lipid variable was found associated with any IMT measurement. Conclusions Baseline data from PHYLLIS indicate that in this population of hypertensive patients with moderate hypercholesterolaemia, SBP and PP are with age among the most significant factors associated with carotid artery alterations. However, the narrow range of inclusion LDL-cholesterol and DBP values may have obscured an additional role of these variables.

Prevalence of extracranial carotid artery disease detectable by echo-Doppler in an elderly population.

Background and Purpose Little information is available on extracranial carotid artery disease in free-living elderly individuals. We sought to evaluate the prevalence of carotid lesions in the elderly. Methods Using echo-Doppler, we assessed the prevalence of possible atherosclerotic lesions in the internal carotid arteries (n=478) and the external and common carotid arteries (n=956) of 239 subjects 65–94 years of age living in retirement homes in Seattle, Wash. Results We found that 152 (31.8%) internal carotid arteries were affected by nonstenosing plaque and 37 arteries (7.7%) had stenosis or occlusion. In addition, 193 (20.2%) external or common carotid arteries showed nonstenosing plaques. There were 128 subjects (53.6%) with internal carotid disease, 106 (44.3%) with evidence of external or common carotid disease, and 75 (31.4%) affected by disease in all three sites. There were 80 subjects (33.5%) with no ultrasound evidence of carotid disease. We found that the presence and severity of carotid disease increased between the decades 65–74 and 75–84. We also demonstrated a positive association between systolic blood pressure and ultrasound evidence of carotid disease that was independent of age. Conclusions The prevalence of extracranial artery disease in an apparently healthy population was high, although stenoses in most instances were not severe. We conclude that noninvasive ultrasound methods identify a relatively small fraction of individuals (5% of the total) at high risk for stroke or transient ischemic attack. Echo-Doppler might be used to monitor further disease progression and to evaluate the efficacy of different therapeutic or preventive interventions.

Hemodynamic changes in the peripheral circulation after repeat low density lipoprotein apheresis in familial hypercholesterolemia.

Repeat low density lipoprotein (LDL) apheresis and blood flow determinations in the forearm and leg were performed in 10 patients (age range, 13-49 years; four male, six female) with familial hypercholesterolemia (eight homozygous, two heterozygous). To perform LDL apheresis, plasma was first separated by a polysulphone hollow fiber filter; then, LDL was selectively removed from plasma by dextran sulphate cellulose beads packed in columns. Blood flows in the forearm and leg were determined at rest and during a reactive hyperemia test (peak flow). This test was performed noninvasively by a strain-gauge plethysmograph with semicontinuous registration of arterial blood flow variables before the first apheresis and 3 weeks after the last of six procedures for apheresis. Resting arterial blood flows in the forearm and leg were slightly increased after repeat LDL apheresis (p less than 0.05). Peak blood flow in the leg significantly increased (+34%, p less than 0.01). No change in peak blood flow in the forearm was observed. Systolic blood pressures were slightly but significantly reduced (p less than 0.05); forearm peripheral resistances were also reduced (p less than 0.05). Flow response was not related to LDL receptor status. Blood and plasma viscosities were determined before and 7 days after the last apheresis. Blood viscosity was significantly reduced after LDL apheresis at shear rates of 11.25-450 sec-1. Plasma viscosity did not change.

Refinement of Variant Selection for the LDL Cholesterol Genetic Risk Score in the Diagnosis of the Polygenic Form of Clinical Familial Hypercholesterolemia and Replication in Samples from 6 Countries

BACKGROUND Familial hypercholesterolemia (FH) is an autosomal-dominant disorder caused by mutations in 1 of 3 genes. In the 60% of patients who are mutation negative, we have recently shown that the clinical phenotype can be associated with an accumulation of common small-effect LDL cholesterol (LDL-C)-raising alleles by use of a 12-single nucleotide polymorphism (12-SNP) score. The aims of the study were to improve the selection of SNPs and replicate the results in additional samples. METHODS We used ROC curves to determine the optimum number of LDL-C SNPs. For replication analysis, we genotyped patients with a clinical diagnosis of FH from 6 countries for 6 LDL-C-associated alleles. We compared the weighted SNP score among patients with no confirmed mutation (FH/M-), those with a mutation (FH/M+), and controls from a UK population sample (WHII). RESULTS Increasing the number of SNPs to 33 did not improve the ability of the score to discriminate between FH/M- and controls, whereas sequential removal of SNPs with smaller effects/lower frequency showed that a weighted score of 6 SNPs performed as well as the 12-SNP score. Metaanalysis of the weighted 6-SNP score, on the basis of polymorphisms in CELSR2 (cadherin, EGF LAG 7-pass G-type receptor 2), APOB (apolipoprotein B), ABCG5/8 [ATP-binding cassette, sub-family G (WHITE), member 5/8], LDLR (low density lipoprotein receptor), and APOE (apolipoprotein E) loci, in the independent FH/M- cohorts showed a consistently higher score in comparison to the WHII population (P < 2.2 × 10(-16)). Modeling in individuals with a 6-SNP score in the top three-fourths of the score distribution indicated a >95% likelihood of a polygenic explanation of their increased LDL-C. CONCLUSIONS A 6-SNP LDL-C score consistently distinguishes FH/M- patients from healthy individuals. The hypercholesterolemia in 88% of mutation-negative patients is likely to have a polygenic basis.

Effects of alpha-adrenergic and beta-adrenergic receptor blockade on lipid metabolism

The role of lipoprotein lipase in the pathophysiology of lipid changes during alpha-receptor or beta-receptor blockade was evaluated in this clinical trial. Thirty hypertensive patients were given 2 mg of prazosin twice daily or 100 mg of metoprolol twice daily for 10 weeks, according to an open, randomized protocol. Both drugs were effective in reducing arterial blood pressure (from 153 +/- 16/102 +/- 6 mm Hg to 146 +/- 12/92 +/- 8 mm Hg with prazosin and from 158 +/- 17/103 +/- 8 to 144 +/- 14/94 +/- 10 mm Hg with metoprolol). Prazosin significantly reduced total plasma cholesterol from 202 +/- 39 to 188 +/- 36 mg/dl and increased high-density lipoprotein cholesterol from 36 +/- 8 to 40.5 +/- 11 mg/dl. Prazosin did not affect plasma triglycerides levels, whereas patients taking metoprolol had a slight rise in these levels, from 122 +/- 42 to 142 +/- 57 mg/dl, along with a decrease in high-density lipoprotein cholesterol from 37 +/- 10 to 31 +/- 8 mg/dl. The concentration of apoprotein B did not change significantly with either treatment. Lipoprotein lipase activity increased in the prazosin group from 28.4 +/- 16 to 37.7 +/- 14 mumol/liter per minute (p less than 0.01), but did not change significantly (29.9 +/- 12 versus 32.8 +/- 8 mumol/liter per minute) in patients treated with the beta blocker. These data, which confirm previous reports of serum lipid changes during antihypertensive therapy, suggest that alpha1 blockers may interfere with lipoprotein lipase, possibly by reducing its catecholamine-mediated inactivation.