European Journal of Cardiovascular Medicine

Cardiovascular diseases continue to represent the leading cause of death and illness worldwide, with coronary artery disease being the most prevalent form [1]. CAD, characterised by atherosclerotic plaque accumulation in the coronary arteries, significantly impairs myocardial perfusion, leading to clinical conditions such as angina, myocardial infarction, and heart failure. Among the numerous modifiable risk factors contributing to CAD, tobacco smoking remains one of the most effective and avoidable causes [2]. In recent decades, extensive epidemiological and clinical research has resolutely established smoking as a primary risk factor not only for the development but also for the progression of coronary artery disease.

Smoking induces atherogenesis through multiple mechanisms. It promotes endothelial dysfunction, improves platelet aggregation, increases oxidative stress, and changes lipid metabolism, all of which contribute to plaque formation and instability [3]. Moreover, the carbon monoxide and nicotine in cigarette smoke led to vasoconstriction and increased myocardial oxygen demand, exacerbating ischemic events. Numerous studies, including large-scale prospective cohorts, have established that smokers are two to four times more probable to develop CAD compared to non-smokers. In addition, smoking has been related to an increased risk of sudden cardiac death, especially in younger populations [4].

In spite of extensive public health campaigns and growing awareness, smoking endures to be a most important public health apprehension, mainly in low- and middle-income countries like India. The Global Adult Tobacco Survey reported that nearly 28.6% of Indian adults use tobacco in some form [5]. Cigarette smoking remains communal in urban areas, while bidi smoking and smokeless tobacco use are more predominant in rural populations. The socio-cultural acceptance, destructive marketing, and limited access to cessation resources contribute to the resolutely high occurrence of tobacco use in India [6].

India is also experiencing an affected rise in the problem of non-communicable diseases, including CAD, driven by changing lifestyles, dietary habits, urbanisation, and increased tobacco consumption. This epidemiological transition is especially evident in tertiary care centres that manage complex and advanced cardiovascular cases [7]. There is a growing need to explore the current pattern and burden of smoking among patients diagnosed with CAD in this situation, not only to appreciate the impact of smoking on disease progression but also to identify opportunities for targeted intervention and preventive methods [8].

This observational study is designed to assess the current scenario of smoking among patients with diagnosed coronary artery disease in a tertiary care centre. The objective is to evaluate the prevalence and patterns of smoking, demographic correlations, clinical presentation, angiographic results, and short-term outcomes in smokers versus non-smokers [9]. By stratifying patients based on their smoking status, current, former, and never-smokers, the study purposes to highlight the association between tobacco exposure and disease severity, including multi-vessel involvement and need for invasive interventions such as percutaneous coronary intervention or coronary artery bypass grafting [10].

Moreover, considering the profile of CAD patients who smoke will help clinicians and public health policymakers identify high-risk groups, enhance smoking cessation involvements, and modify cardiac rehabilitation programs [11]. It is also imperative to investigate patients’ awareness of smoking-related cardiovascular risks and their preparedness to leave, as these factors disapprovingly influence lasting consequences [12].

The aim of this study is to investigate the impact of smoking on coronary artery disease (CAD) severity, coronary angiographic characteristics, and the risk of major adverse cardiac events and all-cause mortality. It compares the cardiovascular outcomes between never smokers, past smokers, and current smokers, assessing how smoking duration and status influence vessel disease and clinical outcomes. The study seeks to quantify the long-term effects of smoking on cardiovascular health and determine the residual risks associated with smoking cessation. By capturing real-world data from a representative clinical cohort, it hopes to contribute to the growing body of literature on tobacco-related CAD and emphasise the urgent need for sustained tobacco control efforts in clinical and community situations.

In this study, a search was showed to shelter light on the intersection between tobacco smoking and coronary artery disease within a tertiary care situation, with the ultimate purpose of informing evidence-based practices in the prevention and management of cardiovascular illness.

Research Design This was a prospective observational study conducted in the Department of Cardiology at the National Institute of Medical Sciences. The study aimed to evaluate the prevalence, patterns, and consequences of smoking among 240 patients with angiographically proven obstructive coronary artery disease. The total duration of the study was one year, and 240 patients were followed up for 12 months from the date of recruitment. Patients were recruited from the inpatient department, including those admitted to the intensive care unit, at the National Institute of Medical Sciences. Recruitment was initiated after coronary angiography, provided the patients met the inclusion criteria. Before enrolment, informed consent was obtained from all participants. At the time of recruitment, comprehensive baseline data were collected. This included demographic information such as age, sex, residential address, education level, and occupation. Clinical information comprised the diagnosis, angiographic findings, and details regarding treatment modality, whether it was medical management, percutaneous coronary intervention, or coronary artery bypass grafting. Particular emphasis was placed on smoking history, including the type of tobacco used, quantity consumed per day, and the duration. In addition, age at smoking initiation, the presence of family opposition to smoking, and the number of smokers in the household were documented to assess social and environmental influences on tobacco use. To quantify nicotine dependence, the Fagerström Test for Nicotine Dependence was administered. Information regarding smokeless tobacco use, if any, was also recorded. Other major cardiovascular risk factors, such as hypertension, diabetes mellitus, dyslipidaemia, and obesity, were systematically evaluated and included in the dataset. All enrolled patients were prospectively followed up for one year. During this follow-up period, data were collected at regular intervals to monitor changes in smoking behaviour, categorised as cessation, continuation, or relapse. Additionally, the occurrence of cardiovascular events was recorded, including new-onset angina, acute coronary syndrome or ST-elevation myocardial infarction, stent thrombosis, the need for repeat revascularisation procedures along with mortality. This follow-up enabled a thorough assessment of the impact of smoking and related risk factors on both short-term and intermediate-term cardiac outcomes. Inclusion Criteria • Patients aged more than 18 years, of either sex. • Patients with obstructive CAD confirmed by coronary angiography, defined as: o ≥70% stenosis in one or more major epicardial coronary arteries o ≥50% stenosis in the left main coronary artery Exclusion Criteria • Patients who refused or were unable to provide informed consent • Patients without angiographic evidence of obstructive CAD • Patients lost to follow-up before 1 year • Critically ill patients with a life expectancy <1 year from non-cardiac illness • Patients with previous coronary artery bypass grafting or PCI done elsewhere without accessible records Statistical Analysis All collected data were initially compiled using Microsoft Excel and subsequently analysed using IBM SPSS 27. Quantitative variables such as age, duration of smoking, and biochemical parameters were summarised using mean ± standard deviation. These variables were compared between groups using the unpaired t-test or analysis of variance, depending on the distribution and study design. Qualitative variables, including smoking status, presence of comorbidities, and treatment modalities, were presented as frequencies and percentages. Group comparisons for these categorical variables were performed using the Chi-square test or Fisher’s exact test when expected cell counts were low. To regulate the independent association of individual risk factors, such as smoking, diabetes, hypertension, dyslipidaemia, and family history, with adverse clinical results, a univariate logistic regression analysis was performed. For all statistical tests, a p-value of less than 0.05 was considered statistically significant.

Table 1 presents baseline demographic and clinical characteristics across smoking status groups. Current smokers are younger (50.65 years) with a higher BMI (29.37) and longer smoking duration (21.61 years) compared to past (60.36 years, 26.95 BMI) and never smokers (57.67 years, 24.41 BMI). Males make up a larger proportion of smokers (59.6%), with a notable dependency in current smokers, indicated by a higher Fagerström test score (7.95).

In Table 2, risk factors and medical histories were compared across groups, with statistically significant differences evident. Hypertension was most frequent among current smokers (65 cases), followed by past smokers (36) and never smokers (31), with a p-value of 0.004, indicating significant association. Diabetes mellitus was predominantly seen in past smokers (29 cases), followed by never smokers (23) and only 13 in current smokers, with a highly significant p-value <0.01. Dyslipidaemia was strikingly higher in current smokers (66), much greater than past (31) and never smokers (22), again highly significant (p<0.01). Family history of CAD was most common in never smokers (40), comparatively lower in past smokers (28), and least in current smokers (14), with a very strong association (p<0.01). Thus, while smoking is strongly related to hypertension and dyslipidaemia, family history of CAD was paradoxically more frequent in never smokers.

Table 1: Baseline Demographic and Clinical Characteristics

Table 2: Risk Factors and Medical Histories in each group and in the whole sample and their respective analysis

Table 3 highlights the distribution of angiographic findings based on smoking status. It shows a significant correlation between smoking and the extent of coronary artery disease. Among the three groups, individuals who never smoked had the highest number of cases with one-vessel disease, totalling 66, followed by past smokers with 50 and current smokers with 47. This trend suggests that smoking status may affect the severity of disease. When it comes to two-vessel disease, current smokers were more affected (39 cases), compared to past smokers (18) and never smokers (4). Three-vessel disease was observed in fewer individuals overall, but it was most prevalent in current smokers, who had 22 cases, compared to 4 past smokers and 2 never smokers. The chi-square analysis indicates that these differences are statistically significant (p < 0.001), highlighting the association between smoking and the severity of coronary artery disease. Overall, current smokers are more likely to suffer from more severe forms of coronary disease compared to those who have quit or never smoked.

Table 3: Angiographic findings in each group and in the whole sample and their respective analysis

In Table 4 shows significant differences in smoking behaviour among the three groups: Never Smokes, Past Smoker, and Current Smoker. Among the Never Smokes group, 71 out of 72 patients (98.6%) have never smoked, with only 1 person (0.4%) having started smoking. In the Past Smoker group, 48 patients (66.7%) have successfully quit smoking, while 24 (33.3%) relapsed after quitting. For the Current Smoker group, 87 participants (90.6%) continue smoking, and only 9 patients (9.4%) have quit. Across the total sample, 87 patients (36.3%) are current smokers, and 57 (23.8%) have quit. The statistical analysis, with a chi-squared value of 435.78 and a p-value of < 0.001, indicates a highly significant difference in smoking behaviour across these groups. This suggests a strong association between smoking status and group membership, with a clear divergence in smoking behaviour depending on whether patients have never smoked, quit smoking, or continue to smoke.

Table 4: Smoking Behavior Re-evaluation in each group and in the whole sample and their respective analysis

*Tukey-B

Table 5 presents the mortality data across the same groups. In the Never Smokes group, 4 patients (1.7%) died, while in the Past Smoker group, 10 patients (4.2%) died. The Current Smoker group had the highest mortality rate, with 13 patients (5.4%) died. In total, 27 patients (11.3%) in the whole sample passed away. The statistical analysis again reveals a highly significant difference in mortality rates between the groups, with a chi-squared value of 435.78 and a p-value of < 0.001. This indicates that smoking status is strongly associated with mortality, with current smokers showing the highest mortality rate, followed by past smokers, and never smokers exhibiting the lowest mortality. These findings suggest that smoking, particularly current smoking, may increase the risk of mortality.

Table 5: Mortality in each group and in the whole sample and their respective analysis

*Tukey-B

In Table 6, the incidence of other events during follow-up is analysed across smoking groups. A majority of participants did not experience any event, with 26.3% of never smokers, 20% of past smokers, and 14.2% of current smokers remaining event-free. Among those who did experience events, current smokers were more likely to suffer from acute coronary syndrome or STEMI (12.1%), repeat revascularization (8.8%), and stent thrombosis (2.5%). Past smokers also had higher rates of these events compared to never smokers, with 4.6% having ACS/STEMI, 2.5% requiring repeat revascularization, and 0.8% experiencing stent thrombosis. In contrast, never smokers experienced fewer such events, with only 0.8% having ACS/STEMI and minimal occurrences of repeat revascularization and stent thrombosis. These differences are statistically significant (p < 0.001), suggesting that smoking behaviour is strongly linked to adverse cardiovascular events. Overall, current smokers have the highest risk of experiencing these events, followed by past smokers, with never smokers having the lowest risk.

Table 6: Other events in follow-up in each group and in the whole sample and their respective analysis

*Tukey-B

Our study found significant differences in health parameters across smokers, past smokers, and never smokers. Current smokers were younger and had the highest levels of nicotine dependence, as indicated by the Fagerstrom score, along with a higher BMI compared to past and never smokers. Smoking was linked to increased prevalence of hypertension, dyslipidemia, and a higher risk of other cardiovascular factors. In our tertiary care cohort, smoking emerged as a dominant modifiable risk factor among patients with angiographically confirmed coronary artery disease, corroborating evidence from diverse Indian studies. For example, the Kashmir Heart Survey reported high smoking prevalence,76% in rural and 67% in urban CAD patients, with its ubiquity across socio-geographic strata [13]. Our results make even with this pattern, reinforce the urgent need for tobacco control efforts in both urban and rural populations.

Consistent with prior research, our study established that smokers presented with more extensive coronary involvement and higher severity indices compared to non-smokers. This mirrors systematic reviews indicating that smoking correlates with greater CAD severity, even though its relationship with the number of occluded vessels remains inconsistent [14]. In our cohort, active smokers had increased multi-vessel disease, echoing observations in ST elevation myocardial infarction cohorts where smoking was associated with more severe angiographic patterns. Similarly, Agrawal et al. observed that in young South Asian CAD patients, smoking was linked to more frequent single-vessel disease but also elevated rates of acute problems [15].

A striking feature of our dataset was the prevalence of premature CAD among younger smokers (<45 years), in keeping with results from Indian tertiary centres. The retrospective study by Nadeem et al. showed that smokers with premature CAD also carried higher rates of hypertension, diabetes, dyslipidaemia, and central obesity compared to smoking controls without CAD [16]. Our analysis infers that the young smokers were more likely than their non-smoking peers to exhibit multiple metabolic comorbidities. These results suggest that tobacco use potentiates other risk factors, fostering an earlier and more aggressive disease phenotype.

Different many prior works that delineate clear urban–rural risk gradients, the Kashmir study found similar high smoking rates in both environments. In our tertiary centre, tertiary referrals from both rural and urban areas showed consistently high smoking prevalence, suggesting that urban–rural differences might diminish as disease worsens and patients reach higher-level care centres.

The detrimental mechanisms linking smoking with CAD, endothelial dysfunction, pro-thrombotic and pro-inflammatory effects, and lipid alterations have been well-established [17]. These processes are probably underpinning our observed results: higher clot problem, impaired coronary flow, and higher rates of in-hospital adverse consequences among smokers. Mostly, our study also found that smokers had suggestively lower HDL levels and more frequent dyslipidaemia, consistent with the mechanistic perceptions described in the literature.

Our results show the need for aggressive tobacco cessation strategies in tertiary situation. Evidence shows that smoking cessation can dramatically improve prognosis after CAD events. Until now, studies like the one by Vijayvergiya et al. have identified persistent gaps in secondary prevention, mainly cessation support, among CAD cohorts. In our centre, fewer than half of active smokers reported receiving formal counselling or pharmacotherapy, indicating substantial room for improvement in integrated cardiovascular care [18].

A unique aspect of this study is the coupling of tobacco exposure data with angiographic severity and specific clinical presentations of CAD, rather than limiting the scope to prevalence alone. By correlating smoking patterns with the extent of coronary vessel involvement, presence of left main disease, thrombus burden, and acute coronary syndrome subtypes, the study adds valuable evidence to the existing literature on the pathophysiologic consequences of tobacco exposure. This approach allows for a more direct evaluation of whether certain patterns of tobacco use are associated with more aggressive disease phenotypes, complementing earlier angiographic studies such as those by Barbash et al. (1995) and Yusuf et al. (2004), which demonstrated an increased burden of severe multivessel disease among active smokers [13,14].

Strengths include the large sample size, inclusion of both young and elderly patients, standardised angiographic and clinical parameters, and comparison across smoking status. Limitations as an observational, single-centre study, causality cannot be established. Recall bias may affect smoking history. In addition, the predominance of male smokers, consistent with other cohorts, limits analysis in women and may reflect social determinants of tobacco use.

Future Directions

Further investigation should explore the outcomes of structured cessation programs in tertiary care environments and assess whether improved access to tobacco pharmacotherapy leads to sustained quitting and reduced recurrent events. In addition, evaluating second-hand smoke exposure, especially among females and children, would help address hidden risks highlighted in broader Indian populations.

The study has concluded that there is a strong and statistically significant association between smoking behavior and adverse cardiac outcomes. Current smokers demonstrated the highest rates of mortality and cardiovascular events, including ACS/STEMI and repeat revascularization, compared to past and never smokers. The chi-squared analyses revealed significant differences in smoking behavior, mortality, and the incidence of cardiac events across the three groups, further supported by the bivariate correlation analysis. Notably, smoking was associated with smaller coronary artery diameters, increased hypertension, and dyslipidemia, all of which are major contributors to cardiovascular risk. These findings shows that the critical role of smoking cessation in mitigating the risk of cardiovascular diseases and mortality, highlighting the need for targeted public health interventions aimed at reducing smoking prevalence and promoting smoking cessation to improve long-term health outcomes. This current study showed distinct differences in health outcomes based on smoking behavior. Current smokers exhibited the highest mortality rate (5.4%) and the greatest incidence of cardiovascular events, including ACS/STEMI (12.1%) and repeat revascularization (8.8%). Past smokers, although showing a reduced risk compared to current smokers, still experienced significant health issues, such as ACS/STEMI (4.6%) and repeat revascularization (2.5%). In contrast, never smokers had the lowest mortality (1.7%) and cardiovascular event rates, with 26.3% remaining event-free. The data further emphasize that while quitting smoking reduces health risks, the benefits are most pronounced in those who have never smoked, suggesting a cumulative adverse effect of prolonged smoking. These results underline the urgent need for effective smoking cessation interventions to mitigate long-term cardiovascular risks. Smoking, particularly current smoking, significantly affects multiple health parameters. Current smokers tend to be younger, more dependent on nicotine, and exhibit higher levels of hypertension, dyslipidemia, and other cardiovascular risk factors. While smoking status significantly impacted the severity of coronary artery disease (CAD), it was also associated with smaller coronary artery diameters, highlighting the negative impact of smoking on vascular health. Additionally, smoking affects blood parameters, kidney function, and lipid profiles, further increasing the risk of cardiovascular events. This study demonstrates a significant association between smoking and various cardiovascular and metabolic risk factors, including hypertension, dyslipidemia, and altered lipid and blood parameters. The study also highlights the complex interplay between lifestyle factors, such as smoking, and genetic components, such as family history, which collectively contribute to the risk of CAD and other cardiovascular diseases. Future research could explore the long-term effects of smoking cessation on CAD progression and vascular health. Longitudinal studies assessing the impact of smoking on coronary artery diameter and the recovery of arterial function post-cessation would be valuable. Additionally, investigating the molecular mechanisms behind the observed correlations could lead to more effective interventions for preventing cardiovascular diseases in smokers.

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