Tobacco use and risk of acute stroke in 32 countries in the INTERSTROKE study: a case-control study.

Background: Smoking is a major risk factor for the global burden of stroke. We have previously reported a global population attributable risk (PAR) of stroke of 12.4% associated with current smoking. In this study we aimed to explore the association of current tobacco use with different types of tobacco exposure and environmental tobacco smoke (ETS) exposure on the risk of stroke and stroke subtypes, and by regions and country income levels. Methods: The INTERSTROKE study is a case-control study of acute first stroke and was undertaken with 13,462 stroke cases and 13,488 controls recruited between January 11, 2007 and August 8, 2015 in 32 countries worldwide. Association of risk of tobacco use and ETS exposure were analysed with overall stroke, ischemic and intracerebral hemorrhage (ICH), and with TOAST etiological stroke subtypes (large vessel, small vessel, cardioembolism, and undetermined). Findings: Current smoking was associated with an increased risk of all stroke (odds ratio [OR] 1.64, 95% CI 1.46-1.84), and had a stronger association with ischemic stroke (OR 1.85, 95% CI 1.61-2.11) than ICH (OR 1.19 95% CI 1.00-1.41). The OR and PAR of stroke among current smokers varied significantly between regions and income levels with high income countries (HIC) having the highest odds (OR 3.02 95% CI 2.24-4.10) and PAR (18.6%, 15.1-22.8%). Among etiological subtypes of ischemic stroke, the strongest association of current smoking was seen for large vessel stroke (OR 2.16, 95% CI 1.63-2.87) and undetermined cause (OR 1.97, 95% CI 1.55-2.50). Both filtered (OR 1.73, 95% CI 1.50-1.99) and non-filtered (OR 2.59, 95% CI 1.79-3.77) cigarettes were associated with stroke risk. ETS exposure increased the risk of stroke in a dose-dependent manner, exposure for more than 10 h per week increased risk for all stroke (OR 1.95, 95% CI 1.69-2.27), ischemic stroke (OR 1.89, 95% CI 1.59-2.24) and ICH (OR 2.00, 95% CI 1.60-2.50). Interpretation: There are significant variations in the magnitude of risk and PAR of stroke according to the types of tobacco used, active and ETS exposure, and countries with different income levels. Specific strategies to discourage tobacco use by any form and to build a smoke free environment should be implemented to ease the global burden of stroke. Funding: The Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada, Canadian Stroke Network, Swedish Research Council, Swedish Heart and Lung Foundation, The Health & Medical Care Committee of the Regional Executive Board, Region Västra Götaland, and through unrestricted grants from several pharmaceutical companies with major contributions from Astra Zeneca, Boehringer Ingelheim (Canada), Pfizer (Canada), MERCK, Sharp and Dohme, Swedish Heart and Lung Foundation, UK Chest, and UK Heart and Stroke.

Interplay of Atherogenic Particle Number and Particle Size and the Risk of Coronary Heart Disease.

BACKGROUND: We examined the interplay of apolipoprotein B (apoB) and LDL particle size, approximated by the LDL-cholesterol (LDL-C)/apoB ratio, on the risk of new-onset coronary heart disease (CHD). METHODS: Participants without cardiovascular disease from the UK Biobank (UKB; n = 308 182), the Women's Health Study (WHS; n = 26 204), and the Framingham Heart Study (FHS; n = 2839) were included. Multivariable Cox models were used to assess the relationship between apoB and LDL-C/apoB ratio and incidence of CHD (14 994 events). Our analyses were adjusted for age, sex (except WHS), HDL-cholesterol (HDL-C), systolic blood pressure, antihypertensive treatment, diabetes, and smoking. RESULTS: In all 3 studies, there was a strong positive correlation between apoB and LDL-C (correlation coefficients r = 0.80 or higher) and a weak inverse correlation of apoB with LDL-C/apoB ratio (-0.28 ≤ r ≤ -0.14). For all 3 cohorts, CHD risk was higher for higher levels of apoB. Upon multivariable adjustment, the association between apoB and new-onset CHD remained robust and statistically significant in all 3 cohorts with hazard ratios per 1 SD (95% CI): 1.24 (1.22-1.27), 1.33 (1.20-1.47), and 1.24 (1.09-1.42) for UKB, WHS, and FHS, respectively. However, the association between LDL-C/apoB and CHD was statistically significant only in the FHS cohort: 0.78 (0.64-0.94). CONCLUSIONS: Our analysis confirms that apoB is a strong risk factor for CHD. However, given the null association in 2 of the 3 studies, we cannot confirm that cholesterol-depleted LDL particles are substantially more atherogenic than cholesterol-replete particles. These results lend further support to routine measurement of apoB in clinical care.

Analysis of apoB Concentrations Across Early Adulthood and Predictors for Rates of Change Using CARDIA Study Data.

The cumulative exposure to apolipoprotein B (apoB)-containing lipoproteins in the blood during early adult life is a central determinant of atherosclerotic cardiovascular disease risk. To date, the patterns and rates of change in apoB through early adult life have not been described. Here, we used NMR to measure apoB concentrations in up to 3055 Coronary Artery Risk Development in Young Adults (CARDIA) Study participants who attended the years 2 (Y2), 7 (Y7), 15 (Y15), 20 (Y20), and 30 (Y30) exams. We examined individual-level spaghetti plots of apoB change, and we calculated average annualized rate of apoB concentration change during follow-up. We used multivariable linear regression models to assess the associations between CARDIA participant characteristics and annualized rates of apoB change. Male sex, higher measures of adiposity, lower HDL-C, lower Healthy Eating Index, and higher blood pressures were observed more commonly in individuals with higher apoB level at Y2 and Y20. Inter- and intra-individual variation in apoB concentration over time was substantial-while the mean (SD) rate of change was 0.52 (1.0) mg/dl/year, the range of annualized rates of change was -6.26 to +9.21 mg/dl/year. At baseline, lower first apoB measurement, female sex, White race, lower BMI, and current tobacco use were associated with apoB increase. We conclude that the significant variance in apoB level over time and the modest association between baseline measures and rates of apoB change suggest that the ability to predict an individual's future apoB serum concentrations, and thus their cumulative apoB exposure, after a one-time assessment in young adulthood is low.

Effect of Selective Androgen Receptor Modulator on Cholesterol Efflux Capacity, Size, and Subspecies of HDL Particles.

Context: Selective androgen receptor modulators (SARMs), because of their preferential muscle vs prostate selectivity, are being developed for muscle-wasting conditions. Oral SARMs suppress high-density lipoprotein cholesterol (HDL-C) but their effects on functional capacity and atherogenic potential of HDL particles are unknown. Objective: To determine the effects of an oral SARM (OPK-88004) on cholesterol efflux capacity, HDL particle number and size, apolipoprotein particle number and size and HDL subspecies. Methods: We measured cholesterol efflux capacity (CEC); HDL particle number and size; APOB; APOA1; and protein-defined HDL subspecies associated with coronary heart disease (CHD) risk in men, who had undergone prostatectomy for low-grade prostate cancer during 12-week treatment with placebo or 1, 5, or 15 mg of an oral SARM (OPK-88004). Results: SARM significantly suppressed HDL-C (P < .001) but HDL particle size did not change significantly. SARM had minimal effect on CEC of HDL particles (change + 0.016, -0.036, +0.070, and -0.048%/µmol-HDL/L-1 at 0, 1, 5, and 15 mg SARM, P = .045). SARM treatment suppressed APOAI (P < .001) but not APOB (P = .077), and reduced APOA1 in HDL subspecies associated with increased (subspecies containing α2-macroglobulin, complement C3, or plasminogen) as well as decreased (subspecies containing APOC1 or APOE) CHD risk; relative proportions of APOA1 in these HDL subspecies did not change. SARM increased hepatic triacylglycerol lipase (HTGL) (P < .001). Conclusion: SARM treatment suppressed HDL-C but had minimal effect on its size or cholesterol efflux function. SARM reduced APOA1 in HDL subspecies associated with increased as well as decreased CHD risk. SARM-induced increase in HTGL could contribute to HDL-C suppression. These data do not support the simplistic notion that SARM-associated suppression of HDL-C is necessarily proatherogenic; randomized trials are needed to determine SARM's effects on cardiovascular events.

Key Questions About Familial Hypercholesterolemia: JACC Review Topic of the Week.

Familial hypercholesterolemia (FH) is characterized as a monogenic, autosomal dominant disorder, producing severe hypercholesterolemia within families due to causal variants within genes regulating the low-density lipoprotein receptor pathway. Demonstration of a causal variant is widely accepted as evidence of substantially higher cardiovascular risk. However, recent large-scale population studies challenge this characterization of FH, which appears to account for only a minor portion of those with severe hypercholesterolemia. Moreover, a substantial portion of FH variant positive patients do not have marked hypercholesterolemia. These discordances raise doubt as to how FH should be defined and how the concentration of low-density lipoprotein in plasma is regulated in individuals with and without FH. Moreover, review of the evidence suggests the impact of an FH causal variant on cardiovascular risk may be less than previously accepted and that all patients with severe hypercholesterolemia should be prioritized for therapy and family screening.

Quantifying Importance of Major Risk Factors for Coronary Heart Disease.

BACKGROUND: To optimize preventive strategies for coronary heart disease (CHD), it is essential to understand and appropriately quantify the contribution of its key risk factors. Our objective was to compare the associations of key modifiable CHD risk factors-specifically lipids, systolic blood pressure (SBP), diabetes mellitus, and smoking-with incident CHD events based on their prognostic performance, attributable risk fractions, and treatment benefits, overall and by age. METHODS: Pooled participant-level data from 4 observational cohort studies sponsored by the National Heart, Lung, and Blood Institute were used to create a cohort of 22 626 individuals aged 45 to 84 years who were initially free of cardiovascular disease. Individuals were followed for 10 years from baseline evaluation for incident CHD. Proportional hazards regression was used to estimate metrics of prognostic model performance (likelihood ratio, C index, net reclassification, discrimination slope), hazard ratios, and population attributable fractions for SBP, non-high-density lipoprotein cholesterol (non-HDL-C), diabetes mellitus, and smoking. Expected absolute risk reductions for antihypertensive and lipid-lowering treatment were assessed. RESULTS: Age, sex, and race capture 63% to 80% of the prognostic performance of cardiovascular risk models. In contrast, adding either SBP, non-HDL-C, diabetes mellitus, or smoking to a model with other risk factors increases the C index by only 0.004 to 0.013. However, primordial prevention could have a substantial effect as demonstrated by population attributable fractions of 28% for SBP≥130 mm Hg and 17% for non-HDL-C≥130 mg/dL. Similarly, lowering the SBP of all individuals to <130 mm Hg or lowering low-density lipoprotein cholesterol by 30% would be expected to lower a baseline 10-year CHD risk of 10.7% to 7.0 and 8.0, respectively (absolute risk reductions: 3.7% and 2.7%, respectively). Prognostic performance decreases with age (C indices for age groups 45-54, 55-64, 65-74, 75-84 are 0.75, 0.72, 0.66, and 0.62, respectively), whereas absolute risk reductions increase (SBP: 1.1%, 2.3%, 5.4%, 10.3%, respectively; non-HDL-C: 1.1%, 2.0%, 3.7%, 5.9%, respectively). CONCLUSIONS: Although individual modifiable CHD risk factors contribute only modestly to prognostic performance, our models indicate that eliminating or controlling these individual factors would lead to substantial reductions in total population CHD events. Metrics used to judge importance of risk factors should be tailored to the research objectives.

Screening Strategies and Primary Prevention Interventions in Relatives of People With Coronary Artery Disease: A Systematic Review and Meta-analysis.

BACKGROUND: Relatives of people with coronary artery disease are at high risk of cardiovascular (CV) disease, but the effect of focused screening and treatment of this population is uncertain. METHODS: We searched the Cochrane Library, Medline, and Embase from inception until June 30, 2014 for articles that described screening strategies and primary prevention interventions targeting family members of patients with coronary artery disease to reduce CV risk. Results were pooled using a random-effects meta-analysis. RESULTS: We identified 18 studies that reported screening strategies and 15 reporting interventions to reduce CV risk. Proband willingness to refer relatives for screening was high (n = 6 studies, pooled rate = 87%; 95% confidence interval [CI], 80%-95%). Studies using a screening strategy in which the relative was contacted by health care professionals reported a pooled participation rate of 88% (95% CI, 78%-99%). The quality of interventional studies was highly variable. Random-effects meta-analysis of the highest quality randomized studies (n = 6) consisting of a specialized risk factor intervention compared with usual care was consistent with modest improvements in low-density lipoprotein cholesterol control (-0.18 mmol/L low-density lipoprotein cholesterol, 95% CI, -0.35 to -0.001; P = 0.048). Improvements in diet, smoking rates, exercise, and blood pressure were also observed with active intervention; however, reported outcomes were heterogeneous precluding a formal meta-analysis. CONCLUSIONS: Screening strategies that target family members, particularly when led by a health care professional, achieve a high participation rate. Although the available evidence is of variable quality, interventions that target individuals with a family history of coronary artery disease appear to be feasible and might be effective in improving certain risk factors or health behaviours but their long-term CV benefits remain uncertain.

Recent advances in the understanding and care of familial hypercholesterolaemia: significance of the biology and therapeutic regulation of proprotein convertase subtilisin/kexin type 9.

Familial hypercholesterolaemia (FH) is an autosomal co-dominant disorder that markedly raises plasma low-density lipoprotein-cholesterol (LDL-C) concentration, causing premature atherosclerotic coronary artery disease (CAD). FH has recently come under intense focus and, although there is general consensus in recent international guidelines regarding diagnosis and treatment, there is debate about the value of genetic studies. Genetic testing can be cost-effective as part of cascade screening in dedicated centres, but the full mutation spectrum responsible for FH has not been established in many populations, and its use in primary care is not at present logistically feasible. Whether using genetic testing or not, cholesterol screening of family members of index patients with an abnormally raised LDL-C must be used to determine the need for early treatment to prevent the development of CAD. The metabolic defects in FH extend beyond LDL, and may affect triacylglycerol-rich and high-density lipoproteins, lipoprotein(a) and oxidative stress. Achievement of the recommended targets for LDL-C with current treatments is difficult, but this may be resolved by new drug therapies. Lipoprotein apheresis remains an effective treatment for severe FH and, although expensive, it costs less than the two recently introduced orphan drugs (lomitapide and mipomersen) for homozygous FH. Recent advances in understanding of the biology of proprotein convertase subtilisin/kexin type 9 (PCSK9) have further elucidated the regulation of lipoprotein metabolism and led to new drugs for effectively treating hypercholesterolaemia in FH and related conditions, as well as for treating many patients with statin intolerance. The mechanisms of action of PCSK9 inhibitors on lipoprotein metabolism and atherosclerosis, as well as their impact on cardiovascular outcomes and cost-effectiveness, remain to be established.

Evaluation of suspected right ventricular pathology in the athlete.

Rigorous training remodels the heart of elite endurance athletes to produce the phenotype of the "athlete's heart." This remodeling, which advantages cardiac performance, creates challenges in the diagnosis of cardiac disorders within this population. This is particularly so for right ventricular pathologies because of the limited number of studies documenting the impact of training on right ventricular remodeling. Although arrhythmogenic right ventricular cardiomyopathy is the focus of this review, several other pathologies that may mimic arrhythmogenic right ventricular cardiomyopathy, including right ventricular outflow tract tachycardia, Wolff-Parkinson-White syndrome, Brugada syndrome, pulmonary embolism, cardiac sarcoidosis, myocarditis, and right ventricular infarction, are also included. In particular, the electrocardiographic findings for each condition are highlighted because this is the most informative and easily accessible diagnostic clinical tool.

The causal exposure model of vascular disease.

Primary prevention of cardiovascular disease is governed at present by the risk factor model for cardiovascular events, a model which is widely accepted by physicians and professional associations, but which has important limitations: most critically, that effective treatment to reduce arterial damage is often delayed until the age at which cardiovascular events become common. This delay means that many of the early victims of vascular disease will not be identified in time. This delay also allows atherosclerosis to develop and progress unchecked within the arterial tree with the result that the absolute effectiveness of preventive therapy is limited by the time it is eventually initiated. The causal exposure model of vascular disease is an alternative to the risk factor model for cardiovascular events. Whereas the risk factor model aims to identify and treat those at markedly increased risk of vascular events within the next decade, the causal exposure model of vascular disease aims to prevent events by treating the causes of the disease when they are identified. In the risk factor model, age is an independent non-modifiable risk factor and the predictive power of age far outweighs that of the other risk factors. In the causal exposure model, age is the duration of time the arterial wall is exposed to the causes of atherosclerosis: apoB (apolipoprotein B) lipoproteins, hypertension, diabetes and smoking. Preventing the development of advanced atherosclerotic lesions by treating the causes of vascular disease is the simplest, surest and most effective way to prevent clinical events.

Should preclinical vascular abnormalities be measured in asymptomatic adults to improve cardiovascular risk stratification?

PURPOSE OF REVIEW: Guideline groups have issued contradictory decisions as to the value of noninvasive tests in asymptomatic adults at intermediate cardiovascular risk. Reclassification has only recently been accepted as a critical criterion to determine the utility of a diagnostic test. The present review examines potential limitations in reclassification and evaluates the utility of carotid ultrasound, pulse wave velocity and ankle brachial index from a clinical perspective. RECENT FINDINGS: Reclassification is less useful than generally believed, because therapy is already indicated in the majority of patients at intermediate risk and it is far from clear that treatment should be withheld in those who are downgraded in risk. Moreover, the additional benefit from more intensive therapy is much less than often thought. Reproducibility, standardization and reference values of noninvasive tests are obligatory before introduction in clinical care. SUMMARY: Routine screening of all those at intermediate risk does not appear to be justified. Screening should be performed on those individuals in whom the noninvasive test changes clinical care, which is most apparent for individuals at intermediate risk with LDL level less than 2.5 mmol/l, in whom positive noninvasive tests will result in the start of statin treatment. The primary value of these tests should not be to determine risk but to identify preclinical anatomic disease.

Ethnic-specific differences in abdominal subcutaneous adipose tissue compartments.

South Asians have a higher prevalence of cardiovascular disease (CVD) than Europeans. Studies have identified distinct subcompartments of subcutaneous adipose tissue (SAT) that provide insight into the relationship between abdominal obesity and metabolic risk factors in different ethnic groups. Our objective was to determine the relationship between SAT compartments and fat-free mass (FFM) between South Asian and European cohorts, and between men and women. Healthy Europeans and South Asians (n = 408) were assessed for FFM via dual energy X-ray absorptiometry, and SAT areas by computed tomography (CT). SAT was subdivided into superficial subcutaneous abdominal adipose tissue (SSAT) and deep subcutaneous abdominal adipose tissue (DSAT). Linear regression analyses were performed using DSAT and SSAT as separate dependent variables and FFM and ethnicity as primary independent variables adjusting for age, gender, income, education, and smoking status. Results showed that South Asian men had significantly higher amounts of DSAT (median 187.65 cm(2) vs. 145.15 cm(2), P < 0.001), SSAT (median 92.0 cm(2) vs. 76.1 cm(2), P = 0.046), and body fat mass (BFM) (25.1 kg vs. 22.6 kg, P = 0.049) than European men. In a fully adjusted model, South Asians showed significantly greater DSAT at any FFM than Europeans. Women had more SSAT at any given FFM than men and less DSAT at any given FFM than men, irrespective of ethnic background. In conclusion, South Asians had more DSAT than Europeans and men had relatively more DSAT than women. These data suggest that specific fat depots are influenced by ethnicity and gender; therefore, could provide insight into the relationship between ethnicity, gender and subsequent risk for CVD.

Plasma acylation-stimulating protein, adiponectin, leptin, and ghrelin before and after weight loss induced by gastric bypass surgery in morbidly obese subjects.

We examined fasting plasma insulin, acylation-stimulating protein (ASP), leptin, adiponectin, ghrelin, and metabolic/cardiovascular risk profile before and 15 +/- 6 months after isolated Roux-en-Y gastric bypass surgery in 50 morbidly obese subjects. Average preoperative plasma lipids were mostly normal, whereas ASP, insulin, and leptin were elevated, and adiponectin and ghrelin were decreased. Postoperatively, body weight decreased significantly (-36.4 +/- 9.6%) and was best predicted by preoperative adiponectin concentration in weight-stable subjects (r = -0.59; P = 0.02). Plasma lipids and insulin resistance improved, leptin and ASP decreased (-76.3 +/- 14.6% and -35.9 +/- 52.2%; P < 0.001), and adiponectin increased (50.1 +/- 47.0%; P < 0.001). The decrease in apolipoprotein B was best predicted by the decrease in ASP (r = 0.55; P = 0.009), whereas the improved postoperative insulin sensitivity was best predicted by the increase in adiponectin (r = 0.70; P = 0.01). Despite bypassing 95% of the stomach and isolating the fundus from contact with ingested nutrients, circulating ghrelin did not decrease after surgery. In fact, plasma ghrelin increased postoperatively in the subset of subjects undergoing active weight loss (+60.5 +/- 23.2%; P < 0.001); ghrelin, however, remained unchanged in weight-stable subjects. In summary, 1) preoperative adiponectin concentrations may be predictive of the extent of weight loss; 2) changes in ASP and adiponectin are predictive of decreased apolipoprotein B and improved insulin action, respectively; and 3) plasma ghrelin increases after gastric bypass surgery in patients experiencing active weight loss.

Effects on apoB-100 secretion and bile acid synthesis by redirecting cholesterol efflux from HepG2 cells.

This study determined the effects of apoA-I, HDL3, or hydroxy-beta-cyclodextrin on apoB-100 secretion and bile acid synthesis by HepG2 cells. The principal observations were that: 1) ApoB-100 secretion into the medium was significantly less after the addition of any of the three agents. 2) Triglyceride mass was not significantly changed from control in the medium but was significantly, although modestly, reduced in the cells. 3) Neither free cholesterol (FC) nor cholesteryl ester (CE) mass in the medium was changed; by contrast, CE mass was reduced within the cells although FC was not. 4) Although the total mass of cholesterol in the medium was unaffected, the proportion associated with apoB-100 was reduced, whereas the proportion associated with the non-apoB-100 fraction was increased. 5) There was also an unanticipated, but substantial, increase in bile acid synthesis induced by apoA-I, HDL3, or hydroxy-beta-cyclodextrin, which was time and concentration dependent, and which was associated with marked increases in cholesterol 7 alpha-hydroxylase activity. There were no significant changes in ACAT activity and only modest increases in HMG-CoA reductase activity. These findings support previous clinical observations that an elevated apoB-100 can accompany a low HDL cholesterol in normotriglyceridemic subjects. They also point to physiologically important, although still only partially understood, metabolic relationships amongst hepatic apoB-100 secretion, cholesterol efflux, and bile acid synthesis.

The chemoattractant receptor-like protein C5L2 binds the C3a des-Arg77/acylation-stimulating protein.

The orphan receptor C5L2 has recently been described as a high affinity binding protein for complement fragments C5a and C3a that, unlike the previously described C5a receptor (CD88), couples only weakly to G(i)-like G proteins (Cain, S. A., and Monk, P. N. (2002) J. Biol. Chem. 277, 7165-7169). Here we demonstrate that C5L2 binds the metabolites of C4a and C3a, C4a des-Arg(77), and C3a des-Arg(77) (also known as the acylation-stimulating protein or ASP) at a site distinct from the C5a binding site. The binding of these metabolites to C5L2 does not stimulate the degranulation of transfected rat basophilic leukemia cells either through endogenous rat G proteins or when co-transfected with human G(alpha 16). C3a des-Arg(77)/ASP and C3a can potently stimulate triglyceride synthesis in human skin fibroblasts and 3T3-L1 preadipocytes. Here we show that both cell types and human adipose tissue express C5L2 mRNA and that the human fibroblasts express C5L2 protein at the cell surface. This is the first demonstration of the expression of C5L2 in cells that bind and respond to C3a des-Arg(77)/ASP and C3a. Thus C5L2, a promiscuous complement fragment-binding protein with a high affinity site that binds C3a des-Arg(77)/ASP, may mediate the acylation-stimulating properties of this peptide.