Short-term effects of the smoke-free legislation on haemostasis and systemic inflammation due to second hand smoke exposure

Cardiovascular injury induced by tobacco products: assessment of risk factors and biomarkers of harm. A Tobacco Centers of Regulatory Science compilation

Although substantial evidence shows that smoking is positively and robustly associated with cardiovascular disease (CVD), the CVD risk associated with the use of new and emerging tobacco products, such as electronic cigarettes, hookah, and heat-not-burn products, remains unclear. This uncertainty stems from lack of knowledge on how the use of these products affects cardiovascular health. Cardiovascular injury associated with the use of new tobacco products could be evaluated by measuring changes in biomarkers of cardiovascular harm that are sensitive to the use of combustible cigarettes. Such cardiovascular injury could be indexed at several levels. Preclinical changes contributing to the pathogenesis of disease could be monitored by measuring changes in systemic inflammation and oxidative stress, organ-specific dysfunctions could be gauged by measuring endothelial function (flow-mediated dilation), platelet aggregation, and arterial stiffness, and organ-specific injury could be evaluated by measuring endothelial microparticles and platelet-leukocyte aggregates. Classical risk factors, such as blood pressure, circulating lipoproteins, and insulin resistance, provide robust estimates of risk, and subclinical disease progression could be followed by measuring coronary artery Ca2+ and carotid intima-media thickness. Given that several of these biomarkers are well-established predictors of major cardiovascular events, the association of these biomarkers with the use of new and emerging tobacco products could be indicative of both individual and population-level CVD risk associated with the use of these products. Differential effects of tobacco products (conventional vs. new and emerging products) on different indexes of cardiovascular injury could also provide insights into mechanisms by which they induce cardiovascular harm.

Mechanisms of Coronary Thrombosis in Cigarette Smoke Exposure

Acute rupture or erosion of a coronary atheromatous plaque and subsequent coronary artery thrombosis cause the majority of sudden cardiac deaths and myocardial infarctions. Cigarette smoking is a major risk factor for acute coronary thrombosis. Indeed, a majority of sudden cardiac deaths attributable to acute thrombosis are in cigarette smokers. Both active and passive cigarette smoke exposure seem to increase the risk of coronary thrombosis and myocardial infarctions. Cigarette smoke exposure seems to alter the hemostatic process via multiple mechanisms, which include alteration of the function of endothelial cells, platelets, fibrinogen, and coagulation factors. This creates an imbalance of antithrombotic/prothrombotic factors and profibrinolytic/antifibrinolytic factors that support the initiation and propagation of thrombosis.

Second-hand tobacco smoke and cardiovascular disease risk: an epidemiological review

In this review, we have sought to examine the epidemiological, basic science, and public health data regarding the association between second-hand smoke (SHS) exposure and the development of coronary heart disease (CHD). SHS increases the risk of CHD by 25-30% according to multiple cohort, case-control, and meta-analytical studies. Physiologic and basic science research suggest that the mechanisms by which SHS affects the cardiovascular system are multiple and include increased thrombogenesis and low-density lipoprotein oxidation, decreased exercise tolerance, dysfunctional flow-mediated vasodilatation, and activation of inflammatory pathways with concomitant oxidative damage and impaired vascular repair. As a result, chronic exposure promotes atherogenesis and the development of cardiovascular disease, increasing the risk of having an acute coronary syndrome (ACS). With the implementation of statewide and nationwide public smoke-free legislation across the United States and Europe, respectively, over the last 10-15 years, there has been a significant and reciprocal decline in the incidence of emergency admissions for ACS by an average 17% despite persistent attempts on the part of the tobacco industry to diminish the correlation between SHS exposure and CHD. These findings underscore the importance of the effects of smoking legislation on community health.

Clot Architecture Is Altered in Abdominal Aortic Aneurysms and Correlates With Aneurysm Size

Objective—

Abdominal aortic aneurysm (AAA) is characterized by widening of the aorta. Once the aneurysm exceeds 5.5 cm, there is a 10% risk of death due to rupture. AAA is also associated with mortality due to other cardiovascular disease. Our aim was to investigate clot structure in AAA and its relationship to aneurysm size.

Methods and Results—

Plasma was obtained from 49 controls, 40 patients with small AAA, and 42 patients with large AAA. Clot formation was studied by turbidity, fibrin pore structure by permeation, and time to half lysis by turbidity with tissue plasminogen activator. Plasma clot pore size showed a stepwise reduction from controls to small to large AAA. Lag phase for plasma clot formation and time to half lysis were prolonged, with smaller AAA samples showing intermediate response. Clot structure was normal in clots made with fibrinogen purified from patients compared with controls, suggesting a role for other plasma factors. Endogenous thrombin potential and turbidity using tissue factor indicated that the effects were independent of changes in thrombin generation.

Conclusion—

Patients with AAA form denser, smaller pored plasma clots that are more resistant to fibrinolysis, and these characteristics correlate with aneurysm size. Clot structure may play a role in AAA development and concomitant cardiovascular disease.