Bernard Lown, MD
The scourge of smoking: tobacco and cardiovascular health
During a good part of my life in medicine I have campaigned against the arms trade as one of the great threats to human life. In recent years I have come to realize that those promoting the global use of tobacco have been far more destructive of life than the arms merchants. In the USA smoking kills over a 1,000 people daily, or 430,000 annually. (1) The use of tobacco imposes on each American a hidden tax for health care of $221 per person per year irrespective whether they smoke, a tax that adds up to $52 billion annually.
While the adverse health effects of tobacco have been debated for at least 400 years, the fact that cigarette smoking is a form of severe drug addiction is just beginning to be appreciated. The reason for this belated recognition, is that unlike other addictive drugs, the effects of tobacco are slow in developing, usually requiring decades of exposure before causing premature disability and death. Furthermore cognitive performance remains unimpaired, social behavior is largely unaffected, and smoking does not predispose to violence. While society criminalizes the use of addictive drugs, the law does not prohibit the sale of tobacco, though it claims far more lives than all drugs combined.
In developed countries smoking accounts for 2 million deaths annually. >From 1950 to the year 2,000 there will have been 60 million such fatalities, of these, two thirds will occur at ages 35-69 and one third in those older. Middle aged people whose death is tobacco related will have lost on average 20-25 years of non -smoker life expectancy. Most of those dying are not particularly heavy smokers, but have generally started the habit as teenagers. Peto et al (2) have estimated that in developed countries during the 1990's, tobacco will cause 30% of all deaths among those 35 to 69 years of age; thereby making cigarette smoking the single largest cause of premature death in the world.
In a number of countries smoking is now in substantial decline. Before the milestone Surgeon Generals Report in 1964, about 40% of US adults smoked; by 1991 this number receded to 25.7%. In Britain smoking has decreased by about 1% annually since 1972. (3) Given the lethality of cigarettes, one can derive little comfort from these figures as nearly a third of British and American people still continue to smoke. Former Surgeon General of the US Public Health Service, C. Everett Koop, identified smoking as the most important public health problem of our time, and the leading cause of preventable death in industrialized countries.
To compensate for the loss of customers, the tobacco companies spend billions of dollars to make smoking appear as a glamorous, adventurous and pleasurable past time. Prodigious resources are invested to target audiences such as women and vulnerable children. The decrease in the number of male smokers in the US is now, in part, compensated by an increase in female smokers. Tobacco consumption is nearly equal in the two groups, with 24 million men and 22 million women. (4) Teen-agers have proved especially susceptible to the hype of advertising. Tobacco is far more injurious when the habit is initiated at a young age. In the US, four out of five smokers start before the age of eighteen. In 1995 one third of high school students reported smoking at least occasionally. Once begun and continued, about half of these young people will eventually be killed by tobacco, of these about one-quarter will die during middle age. The tobacco companies argue that they are not legally liable for health injuring habits of informed adults. Given the deliberate focus to ensnare youngsters in a life long addiction, this is less an issue in exercise of free choice than exploiting callow youth and doing violence to children.
>From a global perspective the reality is even more dismal. The tobacco companies, to compensate for diminishing markets in industrialized countries, are investing enormous wealth to promote the use of cigarettes in the developing world. (More about this in a future commentary). They are succeeding and have already made up for the curtailed use of cigarettes in the developed countries by bloating the global consumption of tobacco. While the toll from smoking is beyond precise reckoning, indubitably, it will dwarf the brutal human sacrifice of all the wars in this bloody 20th century. The annual number of fatalities attributable to cigarettes will quadruple by 2030 and the bulk of these will be in developing countries. (5) Peto has estimated that smoking will exact 10 million premature deaths annually during the next century. (6)
In the public mind the major hazard of cigarettes is the predisposition to cancer especially of the lung, but far more victims are claimed by cardiovascular sequelae. As long ago as 1940, a relation between cigarettes and coronary heart disease (CHD) was reported from the Mayo Clinic. (7) It has since been voluminously documented that smoking substantially increases the risk of cardiovascular disease including stroke, sudden death, myocardial infarction, peripheral vascular disease and aortic aneurysm. Smoking increases the risk for developing coronary disease and enhances the occurrence of events among those with the disease. About one fifth of cardiovascular deaths in the US are attributable to smoking. In a study of British doctors, a strong dose-response relation was observed in men younger than 65 years between duration and extent of smoking and death rate from ischemic heart disease. (8) Similar trends have been noted in female smokers. (9) Women who smoked as few as one to four cigarettes daily had a 2.5 fold increased risk of fatal coronary heart disease and nonfatal myocardial infarction.
The experience of the Coronary Artery Surgery Study (CASS) is relevant. Among those who continued to smoke during the six years while enrolled in the study, the relative risk for cardiac death and for myocardial infarction was 1.7 and 1.5 respectively, as compared to those who gave up cigarettes the year before enrollment and thereafter abstained. This relation held irrespective of age. (10) When smokers and non-smokers were matched for coronary disease severity and subjected to Holter monitoring, the smokers had three times as many ischemic episodes and the duration of the episodes was twelve times longer. (24min vs. 2min /24hrs.) (11) Not only does smoking provoke more active myocardial ischemia during ordinary daily life activities, it also accelerates coronary progression and new lesion formation when assessed by serial quantitative coronary arteriography. Compared to a control group of non-smokers, mean luminal narrowing in coronary arteries more than doubled among smokers during a short period of two years. (12) This effect has also been reported in the carotid arteries of identical twins who were discordant for cigarette smoking. The total area of carotid plaques was 2.3 times larger in smoking twins than their non-smoking siblings. (13)
There is no dearth of possible pathogenic mechanism to account for smoking induced atherogenesis and for the progression of ischemic heart disease. Components of cigarettes have been shown to damage vascular endothelium, the antecedent lesion to atherosclerotic plaque formation. Carbon monoxide, one of the most poisonous by-products of cigarette smoke, makes up approximately 2.7 to 6.0% of smoke. It is known to damage endothelium and thereby enhance the deposition of cholesterol in plaques. Carbon monoxide, additionally increases blood viscosity, fibrinogen levels, and prothrombotic state. Smoking also increases platelet aggregability, thromboxane formation, plasma viscosity and vasomotor reactivity. (14, 15) Furthermore smokers have higher total LDL cholesterol levels and lower HDL than control subjects. The degree of the adverse lipid profile alteration is a function of the daily cigarette consumption. (16)
Some of the cardiovascular adverse effects also relate to the nicotine, a potent stimulator of catecholamine release, which thereby increases oxygen demand, accelerates heart rate and raises blood pressure. Indeed smokers demonstrate an increased rate pressure product both at rest and during exercise.(17). This occurs in a setting where carboxyhemoglobin decreases oxygen delivery. Additionally smoking promotes coronary spasm and impairs coronary vasoreactivity. It is to be expected that this type of combination of factors would lower the vulnerable threshold for ventricular fibrillation (VF). Halstrom and colleagues (18) have, in fact, reported smoking to be a risk factor for recurrence of cardiac arrest among CHD patients who had been resuscitated from VF. Further implicating nicotine as a major smoke component affecting the adrenergic system is the report that propranolol largely abolishes the deleterious effects of smoking on mortality following an initial heart attack. (19)
With the discovery that environmental tobacco smoke (ETS) is a source of indoor contamination, one can no longer argue that smoking is a private and individual matter. In 1986 the National Research Council estimated that 3,000 lung cancer cases per year were attributable to ETS among persons who never smoked.(20) However, the risk of ETS appears far greater for ischemic heart disease. In the US, environmental cigarette smoke is believed to account for 35,000 to 40,000 cardiac ischemic deaths annually among those who have never smoked but have been living with a current or former smoker. (21) It is currently estimated that non-smokers have a 30 percent excess risk for acquiring coronary artery disease when living with smokers. In response to the emerging information on ETS, the American Heart Association affirmed, "A smoke-free environment in the home, public buildings and work place should be the goal of society" (22)
In industrialized societies a public increasingly educated about the hazards of tobacco, has shaped an anti-tobacco political climate. Smoking is no longer deemed a matter of personal choice or a transcendent individual right. The jurisdiction permissible to smokers is ever constricted and is illegal in public buildings, transport vehicles such as busses, trains or planes and in many restaurants. Tobacco companies are increasingly beleaguered. Exposed for the first time are their campaigns of lies about the adverse health effects of smoking that they had already documented decades ago.
Yet, at this very moment, in other parts of the world, smoking is spreading as a veritable fire storm fanned by these same unprincipled and discredited tobacco corporations. This is especially deplorable as the demographic transition exposes for the first time large populations to the risk of ischemic heart disease. The ready availability of tobacco makes a cardiovascular epidemic inevitable. Richard Doll, a giant in cardiovascular epidemiology, recently wrote, "One of the great objectives of medicine is to enable people to live out the span of life to which they are biologically adapted."(23) This is beyond a mere objective of medicine, far more it is the inalienable right of every living human beings. We members of the health profession can not stand idly by when this fundamental right is abridged. We must speak loudly and without equivocation. A single global standard must be forged that strictly curtails the sale of tobacco until the weight of informed public opinion completely proscribes the use of this poisonous weed.Top
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