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

The main risk factor for atherosclerotic cardiovascular disease is smoking. Nicotine and carbon monoxide are two dangerous substances that are found in cigarette smoke. The increased heart rate can have an almost instantaneous impact on the heart and blood vessels. Smoking is well known to cause oxidative stress, endanger the lining of the arteries, and accelerate the accumulation of fatty plaque in the blood vessels. It raises the danger of sudden thrombotic events, inflammatory alterations, and low-density lipoprotein oxidation. The smoke's carbon monoxide decreases the blood's capacity to deliver oxygen, adding to the heart's stress. Notably, these risks increase when diabetes, hypertension, high cholesterol, and glucose intolerance are present. It has a detrimental effect on peripheral blood vessels, raising the possibility of thromboangiitis obliterans. Stroke risk is known to be increased by smoking. As compared to those who continue to smoke, those who give up smoking have a much longer life expectancy. Chronic cigarette smoking has been shown to affect the macrophages' ability to remove cholesterol. Abstinence from smoking enhances the function of high-density lipoproteins and cholesterol efflux, lowering the risk of plaque buildup. In this review, we present the most recent information regarding the causal relationship between smoking and cardiovascular health as well as the long-term advantages of quitting.


Introduction And Background
Smoking is a widespread and compulsive behaviour that has been associated with a number of health issues, including lung illness, cancer, and heart disease. One of the worst side effects of smoking is cardiovascular disease, and the chemicals in tobacco smoke can harm the heart and blood vessels, causing atherosclerosis, coronary heart disease, stroke, and other cardiovascular disorders. Despite the fact that smoking is recognised to be unhealthy, millions of individuals still smoke. As a result, smoking is the top preventable cause of death globally. Many studies have looked at how smoking affects health in general, the heart, and blood vessels. Our review gives a useful summary of the existing literature, evaluates the evidence base critically, points out knowledge gaps, and makes suggestions for future research. Our review could help shape future research, public health policies, and interventions that aim to reduce the number of people who smoke and the health risks that come with it. Given the significant impact of smoking on cardiovascular health and the urgent need for effective smoking cessation interventions, a review of this nature would be a valuable contribution to the field of tobacco control and cardiovascular health. disease (COPD) are two lung diseases that can be caused by smoking. It can cause pulmonary vascular endothelial cells to die, which makes COPD more likely to happen. The pulmonary vascular endothelial cells are important for maintaining the function of blood vessels, and their death can contribute to the pathogenesis of COPD [6].
Also, smoking can affect the reproductive system, which can lead to foetal deaths, stillbirths and trouble in getting pregnant. It can also increase the risk of oral cavity problems like periodontitis [7]. Furthermore, smoking increases the risk of cancer [8,9]. Tobacco smoke is a complex mix of chemicals that includes many mutagens and carcinogens, such as polycyclic aromatic hydrocarbons (PAHs) and tobacco-specific nitrosamines (TSNAs), which are found in all tobacco products, including cigarettes, cigars, and smokeless tobacco. When tobacco is burned or heated it releases these chemicals into the air, where they can be inhaled or ingested by smokers and non-smokers alike. Once inside the body, these chemicals can cause changes to the DNA in cells, leading to mutations and the uncontrolled growth of abnormal cells, which can ultimately result in cancer [10]. Even though everyone knows smoking is bad for health, a lot of people still do it and find it hard to stop because nicotine is so addictive. In this review, we talk about how smoking affects the heart and overall health.

Methods
We conducted our systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) criteria ( Figure 1) [11]  We used the following medical subject headings (MeSH) terms with keywords like "smoking" AND "stroke" AND "Myocardial infarction" AND "coronary heart disease" AND "hypertension" AND "peripheral artery disease" AND "Health" to gather data from the National Library of Medicine (PubMed), PubMed Central (PMC), and Google Scholar. There were 7774 items altogether that were located in electronic databases.

Inclusion and Exclusion Criteria
In our analysis, we looked at all full-text papers, studies with people as subjects, and papers that were published in English. There were papers about smoking's effect on general health and the cardiovascular system published in the last 20 years, from 2002 to 2022 including clinical trials, controlled clinical trials, randomised controlled trials, observational studies, case-control studies, prospective cohort studies, population-based cohort studies, and cross-sectional studies were included.
We didn't include research that didn't involve people or articles that didn't have the full text. Systematic reviews, meta-analyses, and clinical reviews were not considered.

Review
Smoking is linked to a higher risk of poor functional outcomes three months after an acute ischemic stroke, according to a clinical trial conducted by Matsuo et al. on 10,852 patients admitted to multicenter hospitals between July 2007 and December 2017; the study population were patients with acute stroke who had been independent before onset [2]. Patients with thrombolysed AIS comprise the research population in a randomised clinical trial conducted by Sun et al. on 4540 patients in a multicenter setting at the time of patient enrollment. The study's major finding was that young smokers with AIS had higher CVS chances than nonsmokers with AIS [12]. When compared to patients with only one diseased vessel, patients with two or three diseased coronary arteries have a two-to three-fold higher risk of suffering a major adverse cardiac event (MACE), according to a randomised controlled trial conducted on a multicenter sample of 2065 patients by Reinstadler et al. [13]. Cigarette smoking and the effectiveness of oral antiplatelet medications are both modest and unlikely to have clinical effects, according to a clinical trial conducted by Patti et al. in a multicenter with 205 patients. The study population was smokers receiving DES after ST-segment elevation MI [14].
Alotaibi et al. conducted a multicenter, randomised controlled experiment with 24 participants, demonstrating that in the early postprandial interval (0-4 h) after eating, exercise-induced reduction in postprandial triacylglycerol was larger in nonsmokers than in smokers [15]. Chen et al.'s multicentre, randomised controlled trial involved 58 patients, suggesting that smoking cessation did not improve highdensity lipoprotein-induced cellular cholesterol efflux in this study's sample of coronary artery disease smokers (n = 28) and healthy smokers (n = 30) [3]. According to a randomised clinical trial conducted on 319 hospitalised patients by Aung et al., those who received the evidence-based intervention package were about three times more likely to be successful in quitting smoking than those who received standard care [4]. A randomised clinical trial conducted by Schwartz et al. on 8153 patients who attended a panel consultation suggests that hypertension decreases after smoking is stopped; here, the sample population was veterans [16].
The key finding of a randomised clinical trial conducted by Song et al. on 84 hospitalised patients was that apoB and triglyceride levels were higher in NCAD smokers than in nonsmokers. The study's participants were adults aged 40-80 who had smoked at least 10 cigarettes per day for at least 10 years [17]. According to a randomised clinical experiment conducted by Rajaee et al. on 59 hospitalised patients, quitting smoking reduces the severity of vascular disorders in those who have peripheral artery and aneurysmal disease [18]. A correlational study using cross-sectional data was conducted by Perski et al.; here, 223,537 people participated in the open-access online survey. The study's findings show that former daily smokers reported higher levels of bodily pain than non-daily smokers at all ages, indicating that smoking for a prolonged period of time may have an impact on pain perception [19]. According to a longitudinal brain imaging-based observational study conducted in a hospital setting by Petre et al., smoking increases the risk of developing chronic back pain; this effect is mediated by the corticostriatal circuitry that is involved in addictive behaviour and motivational learning. The study population in this instance is made up of patients with chronic back pain, subacute back pain (which includes back pain for 4-12 weeks and back pain without relief for at least a year), and healthy controls [20].
According to a population-based cross-sectional observational study conducted by Watanabe et al. on 23,106 persons (20-79 years of age), smoking is associated with obesity in men who are smokers. Smoking had no impact on female obesity in this study because the participants were general Japanese population smokers who were classified based on their smoking behaviours [21]. According to Chen et al.'s case-control study of 36,000 liver cancer patients and 17,000 cirrhosis patients, smoking increases both men's and women's risk of dying from liver cancer. The study population included 27000 urban and 16000 rural men who had passed away from causes other than suicide, homicide, or accidents, as well as 20,000 urban and 15000 rural male controls [22].
The results of a case-control study conducted by Gajalakshmi et al. on 43,000 adult male dead patients and 35,000 adult male controls show that smoking, which increases the incidence of clinical tuberculosis, is the cause of half the male tuberculosis deaths in India and of a quarter of all male deaths in middle age. The study population here consisted of 36,000 adults who had died from liver cancer (cases) and 17,000 who had died from cirrhosis (controls) [23]. According to a prospective cohort study on 290,000 people conducted by Inoue-Choi et al. people who have smoked one to ten cigarettes over the course of their lives have higher mortality risks than those who have never smoked and might benefit from quitting. These findings further demonstrate that there is no safe threshold for tobacco smoke exposure. In this study, 290 and 215 participants from the AARP Health and Diet Study, aged 59 to 82 years, were included. The study was conducted in 2004 and 2005 [24].
According to a population-based cohort study by Luu et al., smoking raises the risk of the majority of malignancies in men, even at modest doses. Smoking cessation or reduction, particularly when done at a young age, can reduce the incidence and mortality of cancer. Men who completed four health tests in 2002-2003, 2004-2005, 2006-2007, and 2008-2009 were included in their analyses, along with all covered individuals under the national health insurance plan [8]. According to a population-based cohort study conducted by Jee et al. on 430,951 people, the risk of bladder cancer did not change significantly according to the trajectory, with the exception of the low stable group. In order to reduce the risk of bladder cancer in smokers, stopping smoking should be the top priority. In this study, smoking history data were collected from the study population using a self-administered questionnaire. The history of cigarette smoking was coded from 1 to 5. The numbers 1 and 2 represent non-smokers, respectively, whereas the numbers 3 through 5 represent daily cigarette consumption of more than 20 cigarettes [9].
A prospective cohort study conducted by Ott et al. on 17,610 participants in a multicenter setting suggests that smoking may hasten cognitive deterioration in non-demented seniors, with seniors 65 and older making up the study's target demographic [25]. There is a strong correlation between smoking and periodontitis in Thai adults, according to a cross-sectional study conducted by Torrungruang et al. on 2,276 participants. The study population here consisted of senior employees and retired personnel of the Electrical Generating Authority of Thailand (EGAT) [26].
Based on these results and the numerous important discoveries from these 20 studies, we concluded that smoking is associated with an increase in cardiovascular diseases and a decrease in life quality. Hospitals and dialysis centres are where the 20 investigations were conducted. As a result, these findings are not applicable to the non-smoking community.