Cigarette smoking and cardiovascular disease

Effect of ischaemic postconditioning on markers of myocardial injury in ST-elevation myocardial infarction: a meta-analysis

OBJECTIVES

This study aimed to perform a meta-analysis of the short-term impact of ischaemic postconditioning (IPoC) on myocardial injury in ST elevation myocardial infarction (STEMI) using surrogate cardiac biomarkers.

METHODS

Eligible studies were identified using several article databases. Randomised controlled trials published between 1 January 2000 and 1 December 2021 comparing IPoC to standard of therapy in STEMI patients were included in the search. Outcomes included surrogates of myocardial injury, specifically peak troponin, creatine-kinase (CK) and CK myoglobin binding (CK-MB) enzyme levels.

RESULTS

11 articles involving 1273 patients reported on CK-MB and 8 studies involving 505 patients reported on CK. Few studies used troponin as an outcome, thus, a subanalysis of troponin dynamics was not performed. Meta-regression analysis demonstrated no significant effect of IPoC on peak CK-MB (effect size -0.41, 95% CI -1.15 to 0.34) or peak CK (effect size -0.42, 95% CI -1.20 to 0.36). Linear regression analysis demonstrated a significant correlation between a history of smoking and CK-MB in the IPoC group (p=0.038).

CONCLUSIONS

IPoC does not seem to protect against myocardial injury in STEMI, except possibly in smokers. These results resonate with some studies using imaging techniques to ascertain myocardial damage. More research using troponin and cardiac imaging should be pursued to better assess the effects of IPoC on cardiovascular outcomes in STEMI.

Smoking Cessation Reverses Arterial Endothelium-Dependent Relaxation Injury

Chronic smoking is associated with acetylcholine-dependent endothelial dysfunction, an early marker of atherosclerosis. The purpose of this study was to determine whether this effect of smoke exposure on blood vessel endothelium is reversible. New Zealand White rabbits were placed in a 240 cubic-foot air flow chamber for 3 hours per day, 5 days per week, over a 4-week period and were exposed to smoke produced by a robotic smoke generator. After the 4-week period, rabbits (n=four, Smoked) were killed and their superficial femoral arteries (SFAs) were cut into 3-mm segments. The rings were suspended from tension transducers and the maximal contraction of one ring was recorded following stimulation with norepinephrine (NE). The remaining rings were contracted to 50% of the maximum. Relaxation of these rings was determined by adding increasing doses of acetylcholine. The remaining rabbits were placed in and out of the chamber without smoke exposure for an additional 4 weeks (n=five, Reverse-smoked), and then the SFAs were harvested. Control (n=six) SFAs were explanted from rabbits not exposed to smoke. KCl induced increased contractility in the smoked group when compared with the controls, and NE induced increased contractility in the smoked group when compared with the reverse-smoked rabbits. Acetylcholine-dependent relaxation was significantly reduced in the rings from the smoked rabbits when compared with the controls. The percentage ring relaxation in the reverse-smoked rabbits was similar to the control rings.

The impaired acetylcholine-dependent endothelium relaxation in the smoked group verifies endothelial injury. However, the improved relaxation in the reverse-smoked group suggests that endothelial injury is reversible.

Plasma albumin and platelet function: relevance to atherogenesis and thrombosis

Two papers published in this journal(1,2) during the past year remind us that plasma albumin concentrations can influence platelet function. These publications, together with epidemiological evidence showing that low plasma concentrations of albumin predict mortality from cardiovascular disease(3,4) have prompted this review.

Critical review: nicotine for the fetus, the infant and the adolescent?

The recent expansion of Nicotine Replacement Therapy to pregnant women and children ignores the fact that nicotine impairs, disrupts, duplicates and/or interacts with essential physiological functions and is involved in tobacco-related carcinogenesis. The main concerns in the present context are its fetotoxicity and neuroteratogenicity that can cause cognitive, affective and behavioral disorders in children born to mothers exposed to nicotine during pregnancy, and the detrimental effects of nicotine on the growing organism. Hence, the use of nicotine, whose efficacy in treating nicotine addiction is controversial even in adults, must be strictly avoided in pregnancy, breastfeeding, childhood and adolescence.

Medical Expenditure of National Health Insurance Attributable to Smoking among the Korean Population

OBJECTIVES

The purpose of this study was to determine the population-attributable risk (PAR) and estimate the total medical expenditure of the Korean National Health Insurance (KNHI) due to smoking.

METHODS

We used data from the Korean Cancer Prevention Study of 1,178,138 Koreans aged 30 to 95. These data were available from 1992 to 2003 and covered a long-term follow-up period among the Korean population.

RESULTS

The total medical expenditure of KNHI related to smoking increased by 27% from $324.9 million in 1999 to $413.7 million in 2003. By specific diseases, smoking-attributable KNHI medical expenditure was the highest for lung cancer ($74.2 million), followed by stroke ($65.3 million), COPD ($50.1 million), CHD ($49 million) and stomach cancer ($30 million). A total of 1.3 million KNHI patients were suffering from smoking-related diseases in 2003. We predicted rises in total KNHI medical expenditure related to smoking to $675.1 million (63% increase compared with that of 2003) and in the total number of KNHI patients suffering from smoking-related diseases to about 2.6 million (an approximate 100% increase compared with those in 2003) in 2015.

CONCLUSIONS

We found a substantial economic burden related to the high smoking prevalence in South Korea.

Endothelin and erectile dysfunction: a target for pharmacological intervention?

Although erectile dysfunction (ED) is not life threatening, this common problem can significantly affect the quality of life and psychological and social well-being. The Massachusetts male ageing study (1,290 men aged 40 - 70 years) showed that 52% of men reported some degree of ED (17.1% mild, 25.2% moderate, 9.6% total). In the UK, an estimated 17 - 19% of men are thought to suffer from ED. This problem is more common with advancing age and since this proportion of the population is increasing, the prevalence of ED is expected to rise. Endothelin-1 (ET-1) belongs to a family of potent vasoconstrictor peptides consisting of 21 amino acids. We review the evidence showing that ET-1 plays a role via (ET(A) and ET(B) receptors) in the regulation of cavernosal smooth muscle tone. We also consider the various risk factors that are involved in the pathogenesis of ED and how these relate to the action of ET-1. In particular, the role of diabetes, hypertension, smoking and dyslipidaemia are discussed. The pharmaceutical industry has declared an interest in the development of ET antagonists for use in the treatment of various diseases including ED. We briefly comment on experimental ET-1 antagonists that may be of therapeutic benefit in ED.

Statins and renal function

Renal disease is often associated with an increased risk of vascular events. Moreover, an accelerated form of atherosclerosis commonly occurs in these patients. The reasons for these associations are not clearly defined but include the widespread presence of several established risk factors (eg, dyslipidemia, hypertension, and diabetes). Other predictors of atherosclerotic disease may also be abnormally elevated (eg, homocysteine, fibrinogen, and lipoprotein a). In addition, there is evidence that impaired renal function per se predicts vascular risk. Despite this high-risk background, the potential benefit of treatment with statins has not been widely investigated in these patients. The present review considers the evidence (experimental and clinical) that statins exert beneficial effects in patients with different types of renal disease. This includes improved renal function, decreased microalbuminuria, and a fall in blood pressure. Statins may also improve renal allograft survival. The potential mechanisms mediating these effects are considered. The interactions between statins and several risk factors that may be present in patients with impaired renal function are also considered. There is an urgent need to define the role of statins in these high-risk patients. Which is the statin of choice? This question is relevant because impaired renal function can interfere with statin pharmacokinetics. Furthermore, other drugs administered to these patients may cause serious interactions with statins.

Smoking diminishes the beneficial effect of statins: observations from the landmark trials

The landmark statin trials showed a significant reduction in morbidity and mortality associated with ischemic heart disease. However, it may not be widely appreciated that smoking had a marked adverse effect on outcome in these trials. In both the primary and secondary prevention setting, the effect of smoking was broadly similar. Smoking markedly increased the risk of events in the placebo and treatment groups. For example, in the primary prevention trials, this risk was 74-86% higher when smokers were compared with nonsmokers in the placebo groups. The corresponding figures for the secondary prevention trials were 23-61%. The risk of events in untreated nonsmokers was of a similar order to that seen in smokers taking statins. Although statin treatment was associated with a significant reduction in events in smokers, the best outcome was observed in nonsmokers treated with statins (primary prevention: lovastatin or pravastatin; secondary prevention: pravastatin or simvastatin). The highest risk of events in any group was in the smokers on placebo. This information may increase clinician and patient awareness as to the marked harmful effect of smoking relative to effective, evidence-based treatment (ie, the use of statins).

Tobacco-related diseases. Is there a role for antioxidant micronutrient supplementation?

It is clear that smoking causes an increase in free radicals, reactive nitrogen and oxygen species (RNS and ROS, respectively), and that cigarette smoking is associated with increases in the incidence and severity of several diseases including atherosclerosis, cancer, and chronic obstructive lung disease. Although there is still no unequivocal evidence that oxidative stress is a contributor to these diseases or that an increased intake of antioxidant nutrients is beneficial, the observation that smokers have lower circulating levels of some of these nutrients, raises concern. This article discusses the possible links between the observed oxidant-induced damage related to tobacco smoking, effects on cellular mechanisms, and their potential involvement in the causation and enhancement of disease processes.

Ascorbic acid prevents cigarette smoke injury to endothelium-dependent arterial relaxation

BACKGROUND

Arterial endothelium-dependent acetylcholine relaxation is impaired by smoking, and this injury may be mediated by oxygen free radicals. The purpose of this study was to examine the effect of ascorbic acid (AA) treatment on this injury.

MATERIALS AND METHODS

New Zealand White rabbits (n = 6, each group) were placed in a 240-ft3 airflow chamber for 3 h per day, 5 days per week over an 8-week period. Animals were divided into four groups and fed rabbit chow and water or rabbit chow and AA (250 ml/kg)-supplemented water. The control-smoke rabbit group and the ascorbic acid-smoke rabbit group were exposed to mainstream cigarette smoke from a robotic smoke generator for the 3-h period, while the control-no smoke rabbit group and ascorbic acid-no smoke rabbit group were similarly placed in the chamber without smoke. At the end of 8 weeks, rabbits were sacrificed and segments of their superficial femoral arteries were suspended from tension transducers and the maximal contraction was determined. The remaining rings were contracted to 50% of the maximum and relaxation was determined by adding acetylcholine. Groups were compared using one-way ANOVA.

RESULTS

Rings from control-smoke (5.13 +/- 0.21 g) and AA-smoke rabbits (6. 24 +/- 0.46 g) exhibited increased mean contraction to KCl (P < 0. 05) compared to control-no smoke rabbits (3.86 +/- 0.40 g). Acetylcholine-dependent relaxation was significantly reduced in the rings from the control-smoke rabbits compared to control-no smoke rabbits (acetylcholine, 5 x 10(-7) M: 24.7 +/- 2.7% versus 55.3 +/- 8.0%; acetylcholine, 7 x 10(-7) M: 27.5 +/- 2.3% versus 56.3 +/- 9. 2%). The AA-smoke group (acetylcholine, 5 x 10(-7) M: 61.8 +/- 12. 4%; 7 x 10(-7) M: 67.9 +/- 11.4%) had significantly increased relaxation compared to the control-smoke group (P < 0.05). There was no statistical difference in the mean percentage ring relaxation between the control-no smoke, AA-no smoke, and AA-smoke groups.

CONCLUSIONS

Ascorbic acid protected the artery from cigarette smoke-induced endothelial injury.

Smoking and urological disease

It is important to realise that virtually every part of the body, including the urological system, is adversely affected by smoking. Smoking is the most important known preventable cause of urinary bladder cancer and is also associated with a risk of prostatic and renal cancer. The exact mechanism by which smoking increases the incidence of urological malignancy is not known. One possibility is that chemicals in cigarette smoke inhibit the synthesis of cytoprotective eicosanoids. Deficient local protection, against the hostile environment caused by the presence of urine, could then encourage the process of carcinogenesis. Smoking is a powerful predictor of erectile dysfunction; cessation may restore normal function. Cigarette smoke also exerts adverse effects on sperm motility and count. Although there is no convincing evidence of reduced fertility in male smokers, it is advisable for men to quit smoking should they have marginal semen quality and wish to start a family. Smoking causes substantial urological pathology; these facts can be used to convince patients with urological problems to quit smoking.

Cigarette smoking and erectile dysfunction

Erectile dysfunction (ED, formerly referred to as impotence, is a common (especially in diabetic and older men) and distressing condition. Several risk factors have been identified; among these are smoking, hyperlipidaemia, hypertension and diabetes mellitus. These risk factors are shared with atherosclerotic vascular disease (e.g. ischaemic heart disease). This observation underlies a common vascular pathology. Smoking may cause ED by several mechanisms, including adversely affecting intrapenile blood flow. It is important to be aware of the link between smoking and ED since this information may motivate some male smokers to quit. In this context, it is important to be aware of the link between smoking and ED since this information may motivate smokers to quit. In this context, it is relevant that there is evidence that quitting may restore/improve erectile function.

Smoking, diabetes and hyperlipidaemia

The epidemiological evidence linking smoking with insulin resistance is considerable. This evidence is even more convincing because there is a dose response relationship between smoking and the risk of non-insulin dependent diabetes (NIDDM). Similarly, there is a time-dependent decrease in risk of NIDDM for those who quit smoking. Insulin resistance (in the form of impaired glucose tolerance, IGT) may precede the development of NIDDM. There is a biochemical basis for the smoking-IGT/NIDDM relationship. Smoking increases the risk of developing diabetic complications like nephropathy, neuropathy and retinopathy Smoking is also an independent risk factor for myocardial infarction and all-cause mortality in NIDDM. Smokers are both insulin resistant and lipid intolerant. Smoking cessation increases circulating high density lipoprotein (HDL) and reduces low density lipoprotein (LDL) levels, despite weight gain. Those providing advice or treatment to improve cardiovascular risk factors should be aware of these smoking-related harmful effects. This is especially true if IGT is underdiagnosed despite the fact that this condition increases the risk of vascular events. Explaining that smoking increases the chance of developing diabetes as well as raising 'blood fat' levels may convince more smokers to quit.

Cigarette smoking increases endothelial-derived vasorelaxation in the rat carotid artery in a dose-dependent manner

While there is clear-cut epidemiologic, morphologic, and functional evidence to suggest that cigarette smoking is deleterious to the cardiovascular system and endothelium, previous experiments with regard to the effect of cigarette smoking on endothelial-derived vasorelaxation are not conclusive. This study examines the effect of cigarette smoking on endothelium-derived vasorelaxation and its relationship to serum nitric oxide concentrations. Fourteen Sprague-Dawley rats (350-500 g) were divided into two groups (N = 7). The experimental group was exposed to six cigarettes (Kentucky 1R4F) per day for 50 days using a Griffith snout exposure method. The two groups were sacrificed and the carotid arteries were mounted on isometric force transducers in a physiologic bath. The arteries were constricted with norepinephrine (1 x 10(-4) M). Vasorelaxation to acetylcholine (Ach) was measured in a dose response manner. Vasorelaxation to nitroglycerin was measured at 10(-4) M. After the rats were sacrificed, blood samples from each rat were examined for total nitrate/nitrite concentration with serum chemiluminescence on a vanadium column. The results were analyzed with ANOVA and the Student's t test. Vasorelaxation to nitroglycerin was 17.42% +/- 0. 44 versus 16.25% +/- 0.42 in the control and smoke exposure groups, respectively (P = 0.19). This experiment counterintuitively demonstrates that cigarette smoking augments endothelial-derived vasorelaxation. No effect was noted in the endothelium-independent vasorelaxation to nitroglycerin. Alternative mechanisms including the presence of hypoxia and exogenous nitric oxide, which lead to endothelial-dependent and -independent vasorelaxation secondary to cigarette smoking, may serve to explain the apparent augmentation of endothelial-derived vasorelaxation. Further experiments with isolated components of smoke will need to be done to resolve the debate.

High prevalence of smoking in young patients with acute myocardial infarction

Of 35 patients with acute myocardial infarction (AMI) at the age of 40 years or less, 32 (91%) smoked and only three patients were non-smokers. The age at AMI related significantly to the extent of smoking (p < 0.001, Kruskall-Wallis test). Five patients with AMI at the age < 30 years smoked more heavily than the 30 with AMI at the age of 30-40 years (p = 0.04, Mann Whitney U test). Heavy smoking men > 30 years at the AMI had a Q-wave infarction as often (11 of 13 (85%)) as those with multivessel disease or a coronary artery occlusion (8 of 9 (89%) and 14 of 16 (88%) respectively) on coronary arteriography after the infarction. Smoking may be the most important modifiable risk factor in young patients with AMI.