Secondhand smoke as an acute threat for the cardiovascular system: a change in paradigm

Perceived risk and benefit for self and others as predictors of smokers' attitudes towards smoking restrictions

Studies have investigated perceived own risk as a predictor of behavioural change, but only few have investigated perceived risk to others. However, many risks are distributed, affecting other people as much as the 'agents' of the behaviour in question. Further, research on health perceptions has focussed more on risk than benefit even though people generally choose to engage in behaviours because of benefits not risks. The present study investigated the acceptance of smoking restrictions in Germany, a country that at the time of conducting the research had few restrictions on smoking. Smokers (N = 147) rated the benefits and risks of smoking for themselves and others, and their attitudes towards smoking restrictions. We replicated comparative optimism and reality constraints concerning smoking risks. Additionally, we found that participants overestimated their own benefits compared to other smokers ('comparative utility'). Importantly, own benefits but risks to others best predicted the acceptance of smoking regulations. Moreover, smokers who intended to quit differed from those who did not intend to quit. These findings are potentially important for policy makers aiming to broaden acceptance of regulations for risky behaviours: It may be more effective to remind people they are putting others at risk rather than themselves.

Objectively measured secondhand smoke exposure and risk of cardiovascular disease: what is the mediating role of inflammatory and hemostatic factors?

OBJECTIVES

The aim of this study was to examine the association between objectively measured secondhand smoke (SHS) exposure and incident cardiovascular disease (CVD) death and assess the extent to which this association can be explained through novel circulating markers of inflammation and hemostasis.

BACKGROUND

Existing evidence suggests there is an association between SHS and CVD risk, although the mechanisms remain poorly understood.

METHODS

In a prospective study of 13,443 participants living in England and Scotland (age 53.5 +/- 12.6 years, 52.3% women), we measured salivary cotinine (an objective marker of SHS exposure) and novel CVD biomarkers (C-reactive protein, fibrinogen) at baseline.

RESULTS

Of the sample, 20.8% had high SHS exposure on the basis of elevated levels of salivary cotinine (range 0.71 to 14.99 ng/ml). During a mean follow-up of 8 years, there were 1,221 all-cause deaths and 364 CVD deaths. High SHS was associated with all-cause (age-adjusted hazard ratio [HR]: 1.25, 95% confidence interval [CI]: 1.02 to 1.53) and CVD death (age-adjusted HR: 1.21, 95% CI: 0.85 to 1.73). High SHS was also associated with elevated CRP, which explained 48% of the association between SHS and CVD death. The excess risk of CVD associated with active smoking was exaggerated in relation to self report (age-adjusted HR: 3.27, 95% CI: 2.48 to 4.31) compared with objective assessment (age-adjusted HR: 2.44, 95% CI: 1.75 to 3.40).

CONCLUSIONS

Among a large representative sample of British adults we observed elevated levels of low-grade inflammation in otherwise healthy participants exposed to high SHS, and this partly explained their elevated risk of CVD death.

Tobacco smoke induces the generation of procoagulant microvesicles from human monocytes/macrophages

OBJECTIVE

To investigate whether exposure of human monocytes/macrophages to tobacco smoke induces their release of membrane microvesicles (MVs) that carry tissue factor (TF) released from cells, whether smoke-induced MVs are procoagulant, and what cellular processes might be responsible for their production.

METHODS AND RESULTS

We found that exposure of human THP-1 monocytes and primary human monocyte-derived macrophages to 3.75% tobacco smoke extract (TSE) significantly increased their total and TF-positive MV generation. More importantly, MVs released from TSE-treated human monocytes/macrophages exhibited 3 to 4 times the procoagulant activity of control MVs, as assessed by TF-dependent generation of factor Xa. Exposure to TSE increased TF mRNA and protein expression and cell surface TF display by both THP-1 monocytes and primary human monocyte-derived macrophages. In addition, TSE exposure caused activation of C-Jun-N-terminal kinase (JNK), p38, extracellular signal regulated kinase (ERK) mitogen-activated protein kinases (MAPK), and apoptosis (a major mechanism for MV generation). Treatment of THP-1 cells with inhibitors of ERK, MAP kinase kinase (MEK), Ras, or caspase 3, but not p38 or JNK, significantly blunted TSE-induced apoptosis and MV generation. Surprisingly, neither ERK nor caspase 3 inhibition altered the induction of cell surface TF display by TSE, indicating an effect solely on MV release. Inhibition of ERK or caspase 3 essentially abolished TSE-induced generation of procoagulant MVs from THP-1 monocytes.

CONCLUSIONS

Tobacco smoke exposure of human monocytes/macrophages induces cell surface TF display, apoptosis, and ERK- and caspase 3-dependent generation of biologically active procoagulant MVs. These processes may be novel contributors to the pathological hypercoagulability of active and secondhand smokers.

Smoking and atherosclerotic cardiovascular disease: part III: functional biomarkers influenced by smoking

Smoking cigarettes induces rapidly occurring and reversible functional changes in the cardiovascular system, which precede morphologic changes. These functional changes are also related to atherosclerotic disease development and thus may qualify as prognostic parameters in chronic smokers. As opposed to smoking-induced morphologic changes functional alterations occur and revert within minutes, thus, allowing for the detection of smoking-induced effects on the cardiovascular system within minutes following exposure to mainstream smoke. Some alterations represent 'direct' changes (e.g., endothelial function), others reflect changes in a different organ system (e.g., the autonomous nervous system influencing heart rate variability), while some represent the sum of alterations in many organs and systems (e.g., exercise performance influenced by the autonomous nervous and by endothelial and cardiac function). Since a specific functional parameter usually changes with at least one or several others, caution should be exercised when trying to establish a direct cause relationship between the alteration of a single parameter and a clinical outcome.

Short term impact of smoke-free legislation in England: retrospective analysis of hospital admissions for myocardial infarction

OBJECTIVE

To measure the short term impact on hospital admissions for myocardial infarction of the introduction of smoke-free legislation in England on 1 July 2007.

DESIGN

An interrupted time series design with routinely collected hospital episode statistics data. Analysis of admissions from July 2002 to September 2008 (providing five years' data from before the legislation and 15 months' data from after) using segmented Poisson regression.

SETTING

England. Population All patients aged 18 or older living in England with an emergency admission coded with a primary diagnosis of myocardial infarction.

MAIN OUTCOME MEASURES

Weekly number of completed hospital admissions.

RESULTS

After adjustment for secular and seasonal trends and variation in population size, there was a small but significant reduction in the number of emergency admissions for myocardial infarction after the implementation of smoke-free legislation (-2.4%, 95% confidence interval -4.06% to -0.66%, P=0.007). This equates to 1200 fewer emergency admissions for myocardial infarction (1600 including readmissions) in the first year after legislation. The reduction in admissions was significant in men (3.1%, P=0.001) and women (3.8%, P=0.007) aged 60 and over, and men (3.5%, P<0.01) but not women (2.5% P=0.38) aged under 60.

CONCLUSION

This study adds to a growing body of evidence that smoke-free legislation leads to reductions in myocardial infarctions. It builds on previous work by showing that such declines are observed even when underlying reductions in admissions and potential confounders are controlled for. The considerably smaller decline in admissions observed in England compared with many other jurisdictions probably reflects aspects of the study design and the relatively low levels of exposure to secondhand smoke in England before the legislation.

Workplace secondhand smoke exposure in the U.S. trucking industry

BACKGROUND

Although the smoking rate in the United States is declining because of an increase of smoke-free laws, among blue-collar workers it remains higher than that among many other occupational groups.

OBJECTIVES

We evaluated the factors influencing workplace secondhand smoke (SHS) exposures in the U.S. unionized trucking industry.

METHODS

From 2003 through 2005, we measured workplace SHS exposure among 203 nonsmoking and 61 smoking workers in 25 trucking terminals. Workers in several job groups wore personal vapor-phase nicotine samplers on their lapels for two consecutive work shifts and completed a workplace SHS exposure questionnaire at the end of the personal sampling.

RESULTS

Median nicotine level was 0.87 microg/m3 for nonsmokers and 5.96 microg/m3 for smokers. As expected, smokers experienced higher SHS exposure duration and intensity than did nonsmokers. For nonsmokers, multiple regression analyses indicated that self-reported exposure duration combined with intensity, lack of a smoking policy as reported by workers, having a nondriver job, and lower educational level were independently associated with elevated personal nicotine levels (model R2 = 0.52). Nondriver job and amount of active smoking were associated with elevated personal nicotine level in smokers, but self-reported exposure, lack of a smoking policy, and lower educational level were not.

CONCLUSIONS

Despite movements toward smoke-free laws, this population of blue-collar workers was still exposed to workplace SHS as recently as 2005. The perceived (reported by the workers), rather than the official (reported by the terminal managers), smoking policy was associated with measured SHS exposure levels among the nonsmokers. Job duties and educational level might also be important predictors of workplace SHS exposure.

Biological evidence for the acute health effects of secondhand smoke exposure

A vast number of studies on the unfavorable effects of secondhand smoke (SHS) exist within the international literature, the majority of which evaluate longitudinal epidemiological data. Although limited, the experimental studies that assess the acute and short-term effects of exposure to SHS are also increasing in number. They include cellular, animal, and human studies that indicate a number of pathophysiological mechanisms through which the deleterious effects of SHS may arise. This current review evaluates the existing biological evidence regarding the acute health effects of SHS exposure. Analyses on the inhaled toxicants and the carcinogenicity of SHS are included as well as in-depth discussions on the evidence for acute SHS-induced respiratory, cardiovascular, metabolic, endocrine and immune effects, and SHS-induced influences on oxygen delivery and exercise. The influence of the length of exposure and the duration of the observed effects is also described. Moreover, recent findings regarding the underlying pathophysiological mechanisms related to SHS are depicted so as to generate models that describe the SHS-induced effects on different systems within the human body. Based on the presented biological evidence, it is concluded that brief, acute, transient exposures to SHS may cause significant adverse effects on several systems of the human body and represent a significant and acute health hazard. Future research directions in this area include research on the concentrations of tobacco smoke constituents in the alveolar milieu following SHS exposure, individual susceptibility to SHS, as well as the effects of SHS on neurobehavioral activity, brain cell development, synaptic development, and function.

Are there health benefits associated with comprehensive smoke-free laws

INTRODUCTION

In the past few years, comprehensive smoke-free laws that prohibit smoking in all workplaces have been introduced in many jurisdictions in the US, Canada, and Europe. In this paper, we review published studies to ascertain if there is any evidence of health benefits resulting from the implementation of these laws.

METHODS

All papers relating to smoke-free legislation published in or after 2004 were considered for inclusion in this review. We used Pubmed, Google scholar, and Web of Science as the main search tools. The primary focus of the paper is on health outcomes, and thus many papers that only report exposure data are not included.

RESULTS

Studies using subjective measures of respiratory health based on questionnaire data alone consistently reported that workers experience fewer respiratory and irritant symptoms following the introduction of smoke-free laws. Some studies also found measured improvements in the lung function of workers. However, the most dramatic health outcome associated with smoke-free laws has been the reduction in myocardial infarction in the general population. This outcome has been observed in the US, Canada, and Europe, with studies reporting reductions of between 6 and 40%, post-legislation, the larger reductions being mostly from studies with smaller population groups. The evidence as to whether these smoke-free laws have helped smokers to stop smoking or to reduce tobacco consumption is less clear.

CONCLUSIONS

There is now significant body of published literature that demonstrates that smoke-free laws can lead to improvements in the health of both workers who are occupationally exposed and of the general population. There is no longer any reason why non-smokers should be exposed to SHS in any workplace. We recommend that all countries adopt national smoke-free laws that are in line with article 8 of the WHO Framework Convention on Tobacco Control that sets out recommendations for the development, implementation, and enforcement of national, comprehensive smoke-free laws.

Declines in acute myocardial infarction after smoke-free laws and individual risk attributable to secondhand smoke

BACKGROUND

The estimated effects of recent pubic and workplace smoking restriction laws suggest that they produce significant declines in community rates of heart attack. The consistency of these declines with existing estimates of the relative risk of heart attack in individuals attributable to passive smoking exposure is poorly understood. The objective is to determine the consistency of estimates of reductions in community rates of heart attacks resulting from smoking restriction laws with estimates of the relative risk of heart disease in individuals exposed to passive smoking.

METHODS AND RESULTS

Meta-analyses of existing estimates of declines in community rates were compared with a mathematical model of the relationship between individual risk and community rates. The outcome measure is the ratio of community rates of acute myocardial infarction (after divided by before implementation of a smoking restriction law). There is a significant drop in the rate of acute myocardial infarction hospital admissions associated with the implementation of strong smoke-free legislation. The primary reason for heterogeneity in results of different studies is the duration of follow-up after adoption of the law. The pooled random-effects estimate of the rate of acute myocardial infarction hospitalization 12 months after implementation of the law is 0.83 (95% confidence interval, 0.80 to 0.87), and this benefit grows with time. This drop in admissions is consistent with a range of plausible individual risk and exposure scenarios.

CONCLUSIONS

Passage of strong smoke-free legislation produces rapid and substantial benefits in terms of reduced acute myocardial infarctions, and these benefits grow with time.

On the relationship between smoking bans and incidence of acute myocardial infarction

During the last few years several studies have reported a substantial reduction of acute myocardial infarction (AMI) in the general population few months after the enforcement of comprehensive smoking bans. We reviewed the consistency and plausibility of this association, investigating the effect of the Italian law, entered into force on January 10, 2005. We compared the AMI incidence on the first year after the ban with the period before (2000-2004) in the Tuscany population aged 30-64 years. The analysis was performed with a Poisson model of the monthly time-series, adjusting for seasonality and comparing different models with linear and non-linear long-term trends. While the model with linear time trend estimated a decrease of 5.4% (RR 0.95; 95% CI: 0.89-1.00), this effect completely disappeared once the linearity assumption was relaxed (RR 1.01; 95% CI: 0.93-1.10). The model with non-linear terms showed a significantly improved fit (P-value = 0.01). The estimate of the effect of the ban seems to be highly sensitive to the model specification and to the effects of unaccounted factors which could modify the trend of AMI incidence, such as changes in the prevalence of other risk factors or the modification of diagnostic criteria. Several arguments which are put forward to inspect the causal relation between smoking bans and AMI indicate that the plausible effects could be lower than the estimates reported so far.

Environmental tobacco smoke and cardiometabolic risk in young children: results from a survey in south-west Germany

AIMS

We explored the association between exposure to environmental tobacco smoke (ETS) and various cardiometabolic biomarkers in 10-year-old children.

METHODS AND RESULTS

A population-based cross-sectional study was carried out. Data on ETS exposure and potential confounders were collected by parental questionnaire. Adiponectin, leptin, markers of inflammation, apolipoproteins (apo) AI and B, and lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) were measured. Linear and logistic regression models were applied using the 90th percentile as a cut-off point except for adiponectin and apoAI (10th percentile). In linear models, ETS exposure was significantly associated with increasing plasma concentrations of leptin, C-reactive protein, fibrinogen, interleukin (IL)-6, and Lp-PLA(2). When compared with none, ETS exposure of more than 10 cigarettes per day was associated with elevated concentrations of leptin (OR 6.40; 95% CI, 2.67-15.39), C-reactive protein (OR 3.17; 95% CI, 1.31-7.68), Lp-PLA(2) (OR 2.97 95% CI, 1.32-6.68), low adiponectin (OR 2.69; 95% CI, 1.10-6.57), and low apoAI (OR 4.48; 95% CI, 2.16-10.85). Increasing dose of ETS exposure was related to an increasing number of abnormal cardiometabolic markers.

CONCLUSION

Among children, ETS exposure was associated with a low-grade inflammatory response and altered markers of lipid metabolism, which may initiate atherosclerosis in early life. However, longitudinal studies are necessary to determine the potential causal relevance of these associations.

Cardiovascular prevention in clinical practice (ESC and German guidelines 2007)

Preventive efforts should be guided by the patient's global cardiovascular (CV) risk. A risk stratification should be done in every person > age 35 with more than a single risk factor. Recommendations for improved lifestyle are applicable to all persons with CV risk factors: smoking cessation, daily exercise, normal body mass index, Mediterranean diet, blood pressure < 140 mmHg systolic, and LDL cholesterol < 130 mg/dl are beneficial. If the 10-year risk is > or = 20% for CV events or > or = 5% for CV death, additional drug interventions are usually necessary: acetylsalicylic acid 100 mg daily, statins to lower LDL cholesterol to < 100 mg/dl or, in diabetics with coronary artery disease, to < 70 mg/dl, blood pressure should be < 130 mmHg systolic, e.g., in patients with diabetes or renal disease. After bare-metal stent implantation clopidogrel should be given for > or = 4 weeks and after drug-eluting stents for > or = 6 months. In patients after myocardial infarction with an ejection fraction of < 40%, ACE inhibitors and beta-blocker should be started. Influenza vaccination improves prognosis in high-risk patients.

Cigarette smoke extract induces expression of cell adhesion molecules in HUVEC via actin filament reorganization

Epidemiologic studies have shown a strong association between cigarette smoking and cardiovascular diseases. Various oxidative species and free radicals are produced during cigarette smoking and these lead to endothelial dysfunction and inflammation. Expression of adhesion molecules, such as intercellular adhesion molecule-1 (ICAM-1), E-selectin, and vascular cell adhesion molecule-1, and adhesion of leukocytes are present in atherosclerosis. We showed previously that a nonfractionated cigarette smoke extract (CSE) induces surface expression of ICAM-1 and E-selectin in human umbilical vein endothelial cells (HUVEC). We then investigated the role of the MAPKs (ERK1/2, JNK, and p38) and AP-1 and the role of actin cytoskeleton reorganization in the CSE-induced expression of ICAM-1 and E-selectin. Western blot analysis showed that CSE treatment rapidly and significantly caused phosphorylation of JNK and ERK1/2 but not of p38. Cytochalasin D (an actin filament disruptor) partially inhibited CSE-induced ICAM-1 and E-selectin surface expression. However, inhibitors of ERK1/2 (PD98059) and JNK (SP600125) did not attenuate the CSE-induced ICAM-1 and E-selectin surface expression. The results of electrophoretic mobility shift assay showed that CSE enhanced AP-1 binding activity. Therefore, CSE activated AP-1 and upregulated ICAM-1 and E-selectin surface expression in HUVEC seem to be via an MAPK-independent pathway. Moreover, the dynamic reorganization of the actin cytoskeleton seems to be required for the CSE-induced surface expression of ICAM-1 and E-selectin.

Cardiovascular benefits of smoking regulations: The effect of decreased exposure to passive smoking

OBJECTIVES

Decreases in population rates of acute myocardial infarction (AMI) have been repeatedly seen in the first months after the introduction of regulations banning smoking in public places. By decreasing the exposure to passive smoking and its acute cardiovascular effects, smoking regulations may cause an immediate drop in AMI incidence, beginning from the initial days after their introduction. Using simulations, we quantified this expected decrease.

METHODS

Expected AMI decreases were estimated using several parameters, including prevalence of exposure to passive and active smoking, relative risks of AMI associated with active and passive smoking, decrease in exposure to passive smoking after the introduction of the regulation, and level of susceptibility of active smokers to exposure to passive smoking.

RESULTS

After evaluating several possible combinations of these parameters, we found that AMI reductions of 5-15% seem likely. For example, a scenario with a population average of 5 hours per week of overall exposure to passive smoking, a 50% reduction in this exposure after the introduction of the regulation, an acute relative risk (RR) of AMI of 4.5 in the first hour after passive smoking exposure, and similar susceptibility to passive smoking among both active and passive smokers translates into a 8.6% decrease in AMI.

CONCLUSIONS

Smoking regulations can cause immediate and relevant decreases in AMI through the prevention of exposure to passive smoking.

Exercise intolerance and systemic manifestations of pulmonary emphysema in a mouse model

Background

Systemic effects of chronic obstructive pulmonary disease (COPD) significantly contribute to severity and mortality of the disease. We aimed to develop a COPD/emphysema model exhibiting systemic manifestations of the disease.

Methods

Female NMRI mice were treated 5 times intratracheally with porcine pancreatic elastase (emphysema) or phosphate-buffered saline (control). Emphysema severity was quantified histologically by mean linear intercept, exercise tolerance by treadmill running distance, diaphragm dysfunction using isolated muscle strips, pulmonary hypertension by measuring right ventricular pressure, and neurohumoral activation by determining urinary norepinephrine concentration.

Results

Mean linear intercept was higher in emphysema (260.7 ± 26.8 μm) than in control lungs (24.7 ± 1.7 μm). Emphysema mice lost body weight, controls gained weight. Running distance was shorter in emphysema than in controls. Diaphragm muscle length was shorter in controls compared to emphysema. Fatigue tests of muscle strips revealed impaired relaxation in emphysema diaphragms. Maximum right ventricular pressure and norepinephrine were elevated in emphysema compared to controls. Linear correlations were observed between running distance changes and intercept, right ventricular weight, norepinephrine, and diaphragm length.

Conclusion

The elastase mouse model exhibited severe emphysema with consecutive exercise limitation, and neurohumoral activation. The model may deepen our understanding of systemic aspects of COPD.

Renal, vascular and cardiac fibrosis in rats exposed to passive smoking and industrial dust fibre amosite

Passive smoking is an independent risk factor for cardiovascular diseases. Industrial fibrous dust, e.g. the asbestos group member, amosite, causes lung cancer and fibrosis. No data are available on renal involvement after inhalational exposure to these environmental pollutants or of their combination, or on cardiovascular and renal toxicity after exposure to amosite. Male Wistar rats were randomized into four groups (n= 6): control and amosite group received initially two intratracheal instillations of saline and amosite solution, respectively. Smoking group was subjected to standardized daily exposure to tobacco smoke for 2 hrs in a concentration resembling human passive smoking. Combined group was exposed to both amosite and cigarette smoke. All rats were killed after 6 months. Rats exposed to either amosite or passive smoking developed significant glomerulosclerosis and tubulointerstitial fibrosis. Combination of both exposures had additive effects. Histomorphological changes preceded the clinical manifestation of kidney damage. In both groups with single exposures, marked perivascular and interstitial cardiac fibrosis was detected. The additive effect in the heart was less pronounced than in the kidney, apparent particularly in changes of vascular structure. Advanced oxidation protein products, the plasma marker of the myeloperoxidase reaction in activated monocytes/macrophages, were increased in all exposed groups, whereas the inflammatory cytokines did not differ between the groups. In rats, passive smoking or amosite instillation leads to renal, vascular and cardiac fibrosis potentially mediated via increased myeloperoxidase reaction. Combination of both pollutants shows additive effects. Our data should be confirmed in subjects exposed to these environmental pollutants, in particular if combined.

[Secondary prevention after myocardial infarction]

A significant reduction in cardiovascular mortality has been achieved during the last decade. New techniques and materials for early coronary intervention have contributed significantly to reduce early mortality after myocardial infarction. Secondary prevention determines further progress; it combines evidence-based medical treatment as well as lifestyle modifications. ACE inhibitors, angiotensin receptor blockers, and beta-blocker positively affect elevated blood pressure, left ventricular remodeling, and electrical stability. Statins decrease LDL and increase HDL cholesterol. Acetylsalicylic acid and clopidogrel are indicated for antiplatelet therapy. Lifestyle modifications unite a diet rich in polyunsaturated fatty acids, moderate physical activity, weight reduction, and smoking cessation.

Acute effect of sidestream cigarette smoke extract on vascular endothelial function

Acute exposure to passive smoking adversely affects vascular function by promoting oxidative stress and endothelial dysfunction. However, it is not known whether tobacco sidestream (SS) smoke has a greater deleterious effect on the endothelium than non-tobacco SS smoke and whether these effects are related to nicotinic endothelial stimulation. To test these hypotheses, endothelial-dependent relaxation and superoxide anion production were assessed in isolated rat aortas incubated with tobacco SS smoke, non-tobacco SS smoke, or pure nicotine. Tobacco SS smoke decreased the maximal relaxation to acetylcholine (Ach) from 79 +/- 6% to 57 +/- 7.3% (% inhibition of phenylephrine-induced plateau, P < 0.001) and increased superoxide anion production from 31 +/- 9.7 to 116 +/- 24 count/10 sec/mg (P < 0.01, lucigenin-enhanced chemiluminescence technique). The non-tobacco SS smoke extract had no significant effect on the response to Ach but increased superoxide anion production in the aortic wall to 133 +/- 2 count/10 sec/mg (P < 0.001). Furthermore, concentration-response curves to Ach and superoxide production remained unaltered with nicotine (0.001, 0.01, or 0.1 mM). In conclusion, despite similar increases in vascular wall superoxide production with tobacco and non-tobacco SS smoke, only the tobacco SS smoke extracts affected endothelium-dependent vasorelaxation. Nicotine alone does not reproduce the effects seen with tobacco SS smoke, suggesting that the acute endothelial toxicity of passive smoking cannot simply be ascribed to a nicotine-dependent mechanism.

Environmental risk factors for heart disease

In this review, we discuss current evidence linking environmental pollutants to cardiovascular disease (CVD). Extensive evidence indicates that environmental factors contribute to CVD risk, incidence, and severity. Migrant studies show that changes in the environment could substantially alter CVD risk in a genetically stable population. Additionally, CVD risk is affected by changes in nutritional and lifestyle choices. Recent studies in the field of environmental cardiology suggest that environmental toxins also influence CVD. Exposure to tobacco smoke is paradigmatic of such environmental risk and is strongly and positively associated with increased cardiovascular morbidity and mortality. In animal models of exposure, tobacco smoke induces endothelial dysfunction and prothrombotic responses and exacerbates atherogenesis and myocardial ischemic injury. Similar mechanism may be engaged by other pollutants or food constituents. Several large population-based studies indicate that exposure to fine or ultrafine particulate air pollution increases CVD morbidity and mortality, and the plausibility of this association is supported by data from animal studies. Exposure to other chemicals such as polyaromatic hydrocarbons, aldehydes, and metals has also been reported to elevate CVD risk by affecting atherogenesis, thrombosis, or blood pressure regulation. Maternal exposure to drugs, toxins, and infection has been linked with cardiac birth defects and premature CVD in later life. Collectively, the data support the notion that chronic environmental stress is an important determinant of CVD risk. Further work is required to assess the magnitude of this risk fully and to delineate specific mechanisms by which environmental toxins affect CVD.

Short-term secondhand smoke exposure decreases heart rate variability and increases arrhythmia susceptibility in mice

Exposure to secondhand smoke (SHS), a major indoor air pollutant, is linked to increased cardiovascular morbidity and mortality, including cardiac arrhythmias. However, the mechanisms underlying the epidemiological findings are not well understood. Impaired cardiac autonomic function, indexed by reduced heart rate variability (HRV), may represent an underlying cause. The present study takes advantage of well-defined short-term SHS exposure (3 days, 6 h/day) on HRV and the susceptibility to arrhythmia in mice. With the use of electrocardiograph telemetry recordings in conscious mice, HRV parameters in the time domain were measured during the night after each day of exposure and 24 h after 3 days of exposure to either SHS or filtered air. The susceptibility to arrhythmia was determined after 3 days of exposure. Exposure to a low concentration of SHS [total suspended particle (TSP), 2.4 +/- 3.2; and nicotine, 0.3 +/- 0.1 mg/m(3)] had no significant effect on HRV parameters. In contrast, the exposure to a higher but still environmentally relevant concentration of SHS (TSP, 30 +/- 1; and nicotine, 5 +/- 1 mg/m(3)) significantly reduced HRV starting after the first day of exposure and continuing 24 h after the last day of exposure. Moreover, the exposed mice showed a significant increase in ventricular arrhythmia susceptibility and atrioventricular block. The data suggest that SHS exposure decreased HRV beyond the exposure period and was associated with an increase in arrhythmia susceptibility. The data provide insights into possible mechanisms underlying documented increases in cardiovascular morbidity and mortality in humans exposed to SHS.

Exposure to passive smoking: a test to predict endothelial dysfunction and atherosclerotic lesions

Acute exposure to environmental tobacco smoke (ETS) is considered to adversely influence atherogenesis. The aim of this article was to assess whether brachial ultrasonography in subjects with endothelial dysfunction after ETS exposure is associated with atherosclerotic lesions. Never smoker healthy volunteers (n = 18) and subjects with a previous myocardial infarction (MI; n = 10) were studied. Healthy volunteers were 12 men (66%) and 6 women (34%) with a mean age of 34 +/- 9 years. Post-MI subjects were men with a mean age of 53.8 +/- 4.8 years. After assessing endothelial function (by brachial ultrasonography) at rest, study subjects underwent brachial ultrasonography twice: in a smoke-free environment and then in the same environment polluted by cigarette combustion (35 ppm carbon monoxide concentration). Carboxyhemoglobin concentration was measured before and after ETS exposure. Baseline brachial-artery diameter, diameter during reactive hyperemia, and diameter after sublingual nitroglycerin (GTN) administration (endothelium-independent vasodilator) were measured at rest and in both smoke-free and smoking environments. Each study subject acted as their own control. No comparison was made between the two groups. A strong correlation between ETS exposure and endothelial dysfunction was observed in both groups. Post-MI subjects also showed endothelium-independent vasodilation worsening, which is usually due to arterial wall alterations. After ETS exposure, mean flow-mediated vasodilation after GTN was significantly (P < .01) reduced only in post-MI subjects (P < .01). Carboxyhemoglobin concentration increased in both groups (P < .01). ETS exposure may be an effective test to identify endothelial dysfunction and arterial wall alterations by using brachial ultrasonography.

Smoking cessation: lessons learned from clinical trial evidence

PURPOSE OF REVIEW

Cigarette smoking and exposure to secondhand smoke cause coronary heart disease. Cessation dramatically reduces the incidence of primary and secondary cardiac events. The review presents up-to-date information regarding nicotine dependence, recent findings related to its treatment, and recommendations for addressing smoking cessation for the primary and secondary prevention of coronary heart disease.

RECENT FINDINGS

Bans on smoking in public places are associated with significant reductions in the incidence of acute myocardial infarction. Counseling and pharmacotherapy (nicotine replacement therapy, bupropion) are proven, effective treatments for nicotine dependence. Clinical trials of two new pharmacotherapies, varenicline and rimonabant, have recently been reported. Varenicline is a safe and efficacious medication for smoking cessation, and has been approved in the US, Canada and Europe. Rimonabant has shown mixed results for smoking cessation and is undergoing further evaluation.

SUMMARY

All patients should be screened for tobacco use. Clinicians can effectively treat nicotine dependence in the general population using counseling and first-line pharmacotherapies (nicotine replacement therapy, bupropion, varenicline). These same treatments, with some modification, are appropriate for smokers with coronary heart disease; however, brief interventions without follow-up are not effective in this population. For smokers with coronary heart disease, the best time to intervene may be during hospitalization.

Sexual dimorphism in the acute effects of secondhand smoke on thyroid hormone secretion, inflammatory markers and vascular function

Experimental evidence for the physiological effects of secondhand smoke (SHS) is limited, although it affects millions of people globally and its prevalence is increasing, despite currently adopted antismoking measures. Also, scarce evidence suggests that the effects of SHS may be more pronounced in men. We conducted a randomized single-blind crossover study to investigate the sex-specific SHS effects in a controlled simulated bar/restaurant environment on gonadal and thyroid hormones, inflammatory cytokines, and vascular function. Twenty-eight (women = 14) nonsmoking adults underwent a 1-h exposure to moderate SHS and a 1-h control trial. Serum and urine cotinine, gonadal and thyroid hormones, inflammatory cytokines, heart rate, and arterial blood pressure were assessed before exposure and immediately after in both trials. Results showed that testosterone (P = 0.019) and progesterone (P < 0.001) in men and 17beta-estradiol (P = 0.001) and progesterone (P < 0.001) in women were significantly decreased after SHS. In men, SHS was accompanied by increased free thyroxine (P < 0.001), triiodothyronine (P = 0.020), and decreased the triiodothyronine-to-free thyroxine ratio (P = 0.033). In women, significant SHS-induced change was observed only in free thyroxine (P = 0.010), with considerable sex variation in free thyroxine and triiodothyronine and a decrease in luteinizing hormone (P = 0.026) and follicle-stimulating hormone (P < 0.001). After SHS, IL-1beta (P = 0.001) and systolic blood pressure (P = 0.040) were increased in men but not women. We concluded that a 1-h SHS exposure at bar/restaurant levels is accompanied by decrements in gonadal hormones in both sexes and marked increases in thyroid hormone secretion, IL-1beta production, and systolic blood pressure in men.

Tobacco industry efforts undermining evidence linking secondhand smoke with cardiovascular disease

BACKGROUND

The scientific consensus that secondhand smoke (SHS) increases cardiovascular disease (CVD) risk by 30% is based on epidemiological and biological evidence. The tobacco industry has contested this evidence that SHS causes CVD, but how and why they have done it has not been described.

METHODS AND RESULTS

About 50 million pages of tobacco industry documents were searched using general keywords and names of industry consultants and scientists. Tobacco industry-funded epidemiological analyses of large data sets were used to argue against an epidemiological association between SHS and CVD and smoke-free regulations, but these analyses all suffered from exposure misclassification problems that biased the results toward the null. More recent industry-funded publications report an increased risk of CVD associated with SHS but claim a low magnitude of risk. When early tobacco industry-funded work demonstrated that SHS increased atherosclerosis, the industry criticized the findings and withdrew funding. RJ Reynolds focused on attacking the biological plausibility of the association between SHS and CVD by conducting indirect platelet aggregation studies, exposure chamber experiments, and literature reviews. Although these studies also suffered from exposure misclassification problems, several produced results that were consistent with a direct effect of SHS on blood and vascular function. Instead, RJ Reynolds attributed these results to an unproven epinephrine-related stress response from odor or large smoke exposure, which supported their regulatory and "reduced-harm" product development efforts. Philip Morris' recent "reduced-harm" efforts seem supportive of a similar corporate agenda.

CONCLUSIONS

The tobacco industry attempted to undermine the evidence that SHS causes CVD to fight smoke-free regulations while developing approaches to support new products that claim to reduce harm. The industry interest in preserving corporate viability has affected the design and interpretation of their cardiovascular studies, indicating the need for great caution in current debates about future tobacco industry regulation and development of reduced-harm tobacco products.

p38 mitogen-activated protein kinase mediates sidestream cigarette smoke-induced endothelial permeability

Second-hand smoke is associated with increased risk of cardiovascular diseases. So far, little is known about the signaling mechanisms of second-hand smoke-induced vascular dysfunction. Endothelial junctions are fundamental structures important for maintaining endothelial barrier function. Our study showed that sidestream cigarette smoke (SCS), a major component of second-hand smoke, was able to disrupt endothelial junctions and increase endothelial permeability. Sidestream cigarette smoke stimulated the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and myosin light chain (MLC). A selective inhibitor of p38 MAPK (SB203580) prevented SCS-induced loss of endothelial barrier integrity as evidenced by transendothelial resistance measurements. Resveratrol, an antioxidant that was able to inhibit SCS-induced p38 MAPK and MLC phosphorylation, also protected endothelial cells from the damage. Thus, p38 MAPK mediates SCS-induced endothelial permeability. Inhibition of p38 MAPK may have therapeutic potential for second-hand smoke-induced vascular injury.

Acute Effects of Smoking on Skeletal Muscle Microcirculation Monitored by Near-Infrared Spectroscopy

BACKGROUND

Cigarette smoking predisposes to vascular disease. Our study aimed to assess the acute effects of cigarette smoking on peripheral microcirculation using near-infrared spectroscopy (NIRS) and to compare microcirculatory function of smokers with that of nonsmokers.

METHODS

We examined 65 healthy volunteers: 25 smokers (14 men and 11 women; age range, 20 to 27 years) and 40 nonsmokers (31 men and 9 women; age range, 19 to 38 years). Smokers had refrained from smoking for 2 h prior to the examination. Tissue O(2) saturation (Sto(2)), defined as the percentage of hemoglobin saturation in the microvasculature compartments, was measured with a probe placed on the thenar muscle. Sto(2) baseline values were recorded for 5 min. Subsequently, the brachial artery occlusion technique was applied to evaluate microcirculatory function before, during, and after smoking one cigarette.

RESULTS

Sto(2) before smoking was 85 +/- 6% (mean +/- SD), not differing significantly between men and women (84.4 +/- 6.6% vs 85.6 +/- 5.8%, respectively; p = 0.721). Sto(2) did not change significantly during smoking. O(2) consumption rate was significantly greater in women (33.4 +/- 6.7 Sto(2) U/min vs 25.7 +/- 7.1 Sto(2) U/min, p = 0.032) at baseline and throughout the smoking session. O(2) consumption rate was reduced during smoking (p < 0.001) and at 5 min after the smoking session. Smoking had a significant effect on vascular reactivity (p = 0.015), with no significant differences between genders. Five minutes after smoking, vascular reactivity had returned to approximately normal levels.

CONCLUSION

Smoking acutely affects microcirculatory function. NIRS is a noninvasive, operator-independent technique that can document these effects. It seems promising for the prospective evaluation of the effects of long-term exposure to cigarette smoke.

Chronic exposure to second hand smoke and 30-day prognosis of patients hospitalised with acute coronary syndromes: the Greek study of acute coronary syndromes

OBJECTIVE

To investigate the association between chronic exposure to second hand smoke (SHS) and the short-term prognosis of patients hospitalised with acute coronary syndromes.

METHODS

Between 1 October 2003 and 30 September 2004, 2172 consecutive patients enrolled with acute coronary syndromes at the cardiology clinics or the emergency units of six major hospitals, in Greece were studied. Exposure to SHS was measured through a questionnaire administered during a specific interview, after the second day of hospitalisation. The main outcome of interest was the 30-day status of these patients (death, or rehospitalisation due to coronary heart disease).

RESULTS

1003 (46%) of the patients were exposed to SHS. Patients reporting exposure to SHS had 61% (95% CI 14% to 118%) higher risk of having an event during the first 30 days after hospitalisation as compared with patients who were not exposed to SHS, after taking into account the effect of several potential confounders. A dose-response linear relationship was observed between the risk of having recurrent events and the years of exposure to SHS (rho = 0.17, p<0.001).

CONCLUSIONS

Exposure to SHS increases considerably the risk of recurrent events in patients who had survived a cardiac event.