A Systematic Review of the Effects of Smoking on the Cardiovascular System and General Health

**Background:** Smoking is the leading preventable cause of death worldwide and a major risk factor for atherosclerotic cardiovascular disease. Cigarette smoke contains over 7,000 toxic substances including nicotine, tar, carbon monoxide, ammonia, formaldehyde, acrolein, polyaromatic hydrocarbons, and cadmium. These compounds increase heart rate and contractility, cause inflammation, impair endothelial function, promote thrombus formation, lower HDL cholesterol, and reduce the blood's oxygen-carrying capacity via carbon monoxide. Smoking also damages the lungs, reproductive system, bones, and oral cavity, and is associated with multiple cancers. Despite widespread knowledge of these harms, nicotine addiction sustains high smoking rates globally.

**Methods:** The review was conducted according to PRISMA criteria. MeSH terms including 'smoking' AND 'stroke' AND 'Myocardial infarction' AND 'coronary heart disease' AND 'hypertension' AND 'peripheral artery disease' AND 'Health' were used to search PubMed, PubMed Central, and Google Scholar. A total of 7,774 items were identified. Inclusion criteria comprised full-text papers, human studies, English-language publications from 2002–2022, including clinical trials, RCTs, observational studies, case-control studies, prospective/population-based cohort studies, and cross-sectional studies. Exclusion criteria included non-human research, missing full text, systematic reviews, meta-analyses, and clinical reviews.

**Key Results:** The review synthesized findings from 20 studies. For cardiovascular outcomes: Matsuo et al. (2020) found that smokers who quit within two years of ischemic stroke had a higher odds ratio for poor functional outcome (1.75 [1.15–2.66] versus nonsmokers), with risk rising with daily cigarette consumption (P for trend=0.002). Reinstadler et al. (2017) reported that smokers undergoing PPCI for STEMI had significantly lower MACE rates (3.8% vs 8.5%, P=0.01) and mortality (0.9% vs 3.9%, P=0.01) compared to nonsmokers. Alotaibi et al. (2021) found higher postprandial triacylglycerol and C-reactive protein in smokers versus nonsmokers (Cohen's d=0.94, P=0.034). Chen et al. (2019) demonstrated that three months of smoking cessation improved HDL antioxidative and antichemotactic properties in smokers with coronary artery disease, though cellular cholesterol efflux did not increase. Aung et al. (2019) reported that an evidence-based intervention package achieved significantly higher quit rates than standard care (25.62% vs 11.32%; adjusted OR 2.95; 95% CI 1.55–5.61). Song et al. (2015) found that smokers with NCAD and CAD had significantly lower plasma apoA-1 and HDL-cholesterol levels than nonsmokers (p=0.002 and p=0.019, respectively).

FOR GENERAL HEALTH OUTCOMES

Inoue-Choi et al. (2017) demonstrated that even consistent smokers of <1 CPD and 1–10 CPD had increased all-cause mortality risk versus never smokers, with no safe level of exposure. Luu et al. (2022) found steady heavy smokers had higher cancer incidence (HR=1.53; 95% CI: 1.49–1.58) and mortality (HR=2.64; 95% CI: 2.50–2.79) versus never smokers. Chen et al. (2003) reported a 36% increased chance of dying from liver cancer in adult male smokers. Gajalakshmi et al. (2003) found smoking caused half of all male tuberculosis deaths in India and a quarter of all middle-aged male deaths. Ott et al. (2004) showed current smokers had 0.13 points per year greater decline in MMSE score than never smokers (p<0.001). Torrungruang et al. (2005) found current smokers had 4.8 times higher odds of severe periodontitis than nonsmokers.

**Clinical Implications:** The relationship between tobacco smoke exposure and cardiovascular risk is nonlinear, with steep risk increases at low exposure levels including secondhand smoke. Smoking creates a chronic inflammatory state that promotes atherogenesis. Smoking cessation yields substantial benefits: improved HDL function, reduced vascular disease severity, decreased hypertension, and significantly lower mortality. The review confirms that no level of cigarette smoke exposure is risk-free, and smoking cessation should be the top priority for reducing cardiovascular and all-cause mortality. Limitations include the hospital- and dialysis center-based settings of the included studies, which may limit generalizability to non-smoking populations.