The facts regarding the impact of cigarette smoking on the development of cardiovascular disease (CVD) are well known to both the medical profession and the public [1-5]. In spite of the extensive data and efforts to educate the public, many smokers do not believe that smoking is harmful for them (or for those around them via secondhand smoke exposure). As an example, in one study of 737 active smokers, over 60 percent of did not believe that they were at an increased risk for a myocardial infarction (MI) [6].
ally, an estimated 933.1 million people smoke, the majority of whom are male. The majority of smokers reside in low- to middle-income countries. As of 2022, an estimated 11.5 percent of adults ≥18 years of age / the majority of smokers start smoking before the age of 25 years. An estimated 33.9 percent of high school students report consuming tobacco products/An estimated 28.9 percent of high school students report the use of e-cigarettes in the past 30 days [9].
Cigarette smoking and CVD — With respect to CVD, the following observations have been made regarding a major role for cigarette smoking:
●In a cohort of over 550,000 adults, all-cause mortality was significantly associated with current smoking (hazard ratio [HR] 2.8, 95% CI 2.73-2.88), with similar risk observed for males and females. [15].
●The incidence of MI is increased sixfold in female adults and threefold in male adults who smoke at least 20 cigarettes per day compared with subjects who never smoked [16,17]. In the worldwide INTERHEART study of patients from 52 countries, smoking accounted for 36 percent of the population-attributable risk of a first MI [18].
●In a systematic review and meta-analysis of 75 cohorts that evaluated the risks of smoking on coronary artery disease (CAD) and adjusted for the effects of other known CAD risk factors (over 2.4 million persons), female smokers were 25 percent more likely than male smokers to develop CAD (relative risk ratio 1.25, 95% CI 1.12-1.39) [19]. In a study of over 3000 patients recently hospitalized with an acute coronary event, female sex was associated with a higher risk for recurrent cardiac events in the six months after discharge [20].
Dose and duration of smoking exposure — The risk of CVD related to cigarette smoking is present for even very low doses (ie, number of cigarettes), with smokers who consume less than five cigarettes per day having an increased risk for CVD events such as acute MI. Smoking even one cigarette per day is associated with approximately 50 percent increased risk for CAD and approximately 25 percent increased risk for stroke [30].
With increases in the number of cigarettes smoked per day, increased risk for CVD has been observed in several studies [21,30-35]. As examples:
Data from the National Health Interview Survey from 329,035 United States adults observed a significant increase in all-cause mortality among those who smoked one to two cigarettes per day (HR 1.93, 95% CI 1.73-2.16) and three to five cigarettes per day (HR 1.99, 95% CI 1.83-2.17) compared with never smokers and after adjustment for demographic, clinical, and lifestyle factors [36]. Death due to CVD was also increased for those smoking one to two cigarettes per day (HR 1.92, 95% CI 1.58-2.36) and three to five cigarettes per day (HR 1.96, 95% CI 1.63-2.35).
●Patients who continue to smoke in the presence of established CAD have an increased risk of repeat MI and an increased risk of death, including sudden cardiac death [22-25]. Furthermore, smoking multiplies the risk of CVD when other risk factors such as diabetes mellitus are present [26,27]. Among smokers who quit after MI, risk for recurrent events declines over time [28].
●Patients who continue to smoke following revascularization (either percutaneous coronary intervention or coronary artery bypass grafting) have significantly higher mortality compared with those who quit smoking.
●Smokers are at high risk for peripheral arterial disease (PAD). Among a cohort of 22,203 patients with PAD, including 1995 patients who smoke, almost 50 percent of smokers were hospitalized over a one-year follow-up period, significantly higher than PAD patients who do not smoke [29].
In the Pooling Project on Diet and Coronary Heart Disease study, which pooled data from eight prospective studies including 266,787 adults ages 40 to 89 years who were enrolled between 1974 and 1996 and followed for an average of up to eight years, current smokers who smoked 15 or more cigarettes per day had almost 2.5 times the risk of CAD compared with a nonsmoker [31]. For those who smoked less than 15 cigarettes per day, the risk of CAD was near double that of a nonsmoker.
In the US Veterans study, the risk for CAD among current smokers ranged from 1.24 for those who smoked <10 cigarettes per day to 1.56 for those who smoked 10 to 20 cigarettes per day, and 1.76 for those who smoked between 20 and 40 cigarettes per day [32]. The highest CAD risk of 1.94 was observed for those who smoked 40 or more cigarettes per day.
In the ARIC (Atherosclerosis Risk in Communities) study, which enrolled 10,914 patients and measured intima-medial thickness of the carotid artery by ultrasound over a three-year period, current smoking was associated with a 50 percent increase in the progression of atherosclerosis versus nonsmokers [38]. Additionally, patients with environmental tobacco smoke exposure (ie, secondhand smoke) had a 20 percent greater rate of atherosclerosis progression compared with patients without secondhand smoke exposure.
Secondhand smoke — Exposure to secondhand smoke increases nonsmokers’ risk of CVD. While the risk estimates for secondhand smoke and CAD outcomes vary, most studies show modest increases in risk. The impact of secondhand smoke on the cardiovascular system is discussed separately. (See “Secondhand smoke exposure: Effects in adults”, section on ‘Cardiovascular disease and stroke’.)
Electronic cigarettes — Data on the relationship between electronic cigarette (e-cigarette) use and its impact on CVD outcomes are limited. However, of concern are the rates of new smokers who report initially starting e-cigarette use before starting to smoke cigarettes [54]. Furthermore, in a study of 449,092 participants, those who reported the dual use of e-cigarettes and combustible traditional cigarettes had a higher odds for CVD (OR 1.36, 95% CI 1.18-1.56) compared with those who reported smoking combustible cigarettes alone [55]. E-cigarettes have been associated with higher levels of inflammatory biomarkers and vascular dysfunction, both associated with an increased risk for CVD [9,55,56].
