Unfolding the reality of the smoking paradox in a South Asian cohort of patients presenting with ST-elevation acute coronary syndrome undergoing primary percutaneous coronary intervention.

OBJECTIVES

Smoking is a potent risk factor for coronary artery disease, but there is controversy about its protective nature in terms of prognosis in ST-elevation acute coronary syndrome patients undergoing primary percutaneous coronary intervention. So, the main objective of this study is to unfold this controversy in a South Asian population in terms of clinical angiographic parameters and its in-hospital outcomes.

METHODS

In this study, we included 1756 consecutive patients diagnosed with ST-elevation acute coronary syndrome undergoing primary percutaneous coronary intervention. Patients were classified into smokers and non-smokers, and the in-hospital mortality rate was compared. Multivariable logistic regression analysis was performed to evaluate the paradoxical role of smoking.

RESULTS

Smokers were younger (53.78 ± 11.16 years vs 56.43 ± 11.17 years;  < 0.001) and more frequently men (98.7% vs 69.9%;  < 0.001) and had less diabetes (19.6% vs 44.8%;  < 0.001) and hypertension (38.5% vs 64.9%;  < 0.001). Smokers presented less frequently in Killip III (5.6% vs 8.1%;  < 0.001) and Killip IV (2.5% vs 4.8%;  < 0.001). Smokers mostly had single vessel disease (41.7% vs 34.4%;  = 0.013), whereas non-smokers had the multi-vessel disease and frequently presented with total occlusion of the culprit vessel (64.6% vs 58.8%;  = 0.040). Smokers have significantly lesser mortality (1.8% vs 4.3%;  = 0.009) compared to non-smokers with an odds ratio of 0.41 (95% confidence interval (CI): 0.21-0.82,  = 0.011); however, adjusted odds ratio on multivariable analysis was 0.67 (95% CI: 0.31-1.41,  = 0.290).

CONCLUSIONS

The paradoxical protective role of smoking is the confounding effect of mainly younger age, less coronary artery disease burden, lower prevalence of diabetes and hypertension, and lower Killip III/IV at presentation.