**6. Tobacco- and e-cigarettes-induced cardiomyopathy**

#### **6.1 Tobacco-induced cardiomyopathy**

The tobacco-induced cardiomyopathy accounts for 9.4 million, or 16.6%, of the 56 million deaths worldwide each year [99]. Smoking causes 1.62 million (18%) deaths from heart disease worldwide [100], and cause severe ill health, with an estimated 40.6 million daily lost to heart disease [100].

Tobacco use (smoked and smokeless) and exposure to secondhand tobacco causes heart disease through a variety of mechanisms, including inflammation, blood vessels shrinkage, clot formation, and reduced oxygen supply (**Figure 1**) [101–103]. Smoking-mediated thrombosis appears to be a major factor in the pathogenesis of acute cardiovascular disease [101]. Nicotine stimulates the heart, which increases the demand for oxygen to the heart muscle, triggering angina. Smokers are more likely to develop acute cardiovascular disease at a young age and early in their illness [101]. The associated effects of exposure to secondhand smoke on the heart are almost as severe as the effects of smoking itself, and likely through the same biological mechanisms [104]. Exposure to secondhand smoke in as little as 1 h can increase the risk of heart attack [105].

Risk of damage to the cardiovascular system increases with duration of smoking and the amount and type of smoking tobacco products consumed. However, the close relationship between dose and response is not linear [101]. Even with low exposure levels, the risk increases substantially—people who smoke only one cigarette a day have half the risk of coronary heart disease as those who smoke at least 20 cigarettes a day [106]. In addition to being a major independent risk factor for coronary heart disease, smoking may act synergistically with other major risk factors for coronary heart disease, such as high cholesterol, untreated hypertension, and diabetes [107, 108]. In 2017, an estimated 382 000 deaths from coronary heart disease were attributable to exposure to secondhand smoke [106], accounting for 4.3% of total deaths from coronary heart disease and 31% of total deaths from exposure to secondhand smoke [106]. In the same year, exposure to secondhand smoke was also estimated to be responsible for an estimated 8.8 million disability-adjusted life-years (DALYs) lost to coronary heart disease [106]. Various systematic reviews and meta-analyses have shown that adults exposed to secondhand smoke have a 23–30% increased risk of coronary heart disease in countries with high to low-income levels [101, 109–112]. Cohort studies conducted in multiple countries in the 1970s and 1980s showed that children's exposure to secondhand smoke has adverse effects on cardiovascular disease, including premature atherosclerosis [113, 114]. A major challenge in these studies is accurately assessing lifetime exposure to secondhand smoke. The cumulative total lifetime exposure to secondhand smoke may be much higher than reflected during the study period [104], which may lead to an underestimation of the true risk of exposure to secondhand smoke and the impact on heart disease [104]. A recent study led by the tobacco industry claims that electronic nicotine delivery systems (ENDS) are less harmful than cigarettes [115, 116]. However, ENDS may be more toxic than inhaled ones at low in conventional cigarettes and tobacco products, but they are not harmless, and there

are risks associated with use and secondhand exposure [41, 117]. ENDS linked to increased risk of cardiovascular disease Association [118, 119]. The toxic substances contained in these products can lead to causes impaired endothelial function, arterial stenosis, increased heart rate and increased blood pressure [120–122]. Concomitant use with smoking (this is most ENDS common practice of users), effects of a combination of two or more products [123]. Tobacco control measures have been shown to benefit heart health place. For example, raising tobacco taxes is directly related to reducing tobacco consumption. Associated with improved heart health [124].

#### **6.2 E-cigarettes-induced cardiomyopathy**

Due to the many pathogenic and negative effects on the heart from smoking on the heart, the market for smoking and nicotine replacement has grown rapidly in recent years. Since 2006, e-cigarettes have become more popular due to their perceived safety profile compared to traditional cigarette smoking. An electronic cigarette (or e-cigarette) is a battery-operated device for heating solutions (or e-liquids) containing nicotine, propanediol alcohol and vegetable glycerin [120, 125, 126]. E-cigarettes not only attract smokers who are trying to quit smoking, but are also becoming more popular among non-smokers, who have even become the main force in the e-cigarette market. Since the advent of electronic cigarettes, its design has constantly changed, but there has been little regulatory control. Common forms of e-cigarettes are the first generation of disposable "Cigalikes", the second generation of rechargeable devices, and the third generation of water tanks, pens and personalized large cigarettes, boxes, and pod-based devices.

The team of Nicholas D Buchanan of The Ohio State University School of Medicine published a paper in the journal Cardiovascular Research, reviewing clinical studies related to the cardiovascular risk of e-cigarettes. This review discusses recent relevant studies from the existing literature, focusing on components and potential cardiovascular risks associated with e-cigarette vapor exposure and on evaluating and broadly discussing data from preclinical and epidemiological studies on the cardiovascular effects of acute (short-term) and chronic (long-term) exposure to e-cigarettes [127]. e-cigarettes increased hyperlipidemia [128], sympathetic dominance [129], endothelial dysfunction [130], DNA damage [131], macrophage activation [132, 133]. Multiple studies suggest e-cigarettes may increase CVD risk.
