A retrospective cross-sectional study on the association between tobacco smoking and incidence of ST-segment elevation myocardial infarction and cardiovascular risk factors.

Background: Cigarette smoking is a well-established risk factor for the development of coronary heart disease. However, the relationship between smoking and acute ST-segment elevation myocardial infarction (STEMI) is less well described.

Objective: To determine the relative risk of acute STEMI in smokers and ex-smokers, compared with individuals who had never smoked.

Methods: This observational study studied all patients with STEMI undergoing percutaneous coronary intervention (PCI) in South Yorkshire, UK from 1 January 2009 to 6 April 2012. Additional contemporary demographical data for the South Yorkshire population, supplied by the Office for National Statistics, allowed derivation of the incidence rate of STEMI in South Yorkshire-both overall and stratified by smoking status. Incidence rate ratios and population attributable risk (PAR) were calculated to quantify STEMI risk.

Results: There were 1715 STEMIs in 1680 patients during the study period. Smoking status was obtained in 96.2% patients. The prevalence of smoking was 47.3% in patients with STEMI and 22.0% in the general population. In patients with STEMI, smokers were ∼10 years younger, mean (SD) 57.2 (11.1) years, than never-smokers, 66.4 (12.1) years, and ex-smokers, 67.9 (11.9) years. The age-standardised incident rate ratio of STEMI was 5.2 (4.5-6.1) for current smokers and 1.1 (1.0-1.3) for ex-smokers, with the reference group being never-smokers for both. Almost 50% of STEMIs were attributable to smoking (PAR=48.3%).

Conclusion: Cigarette smoking is associated with a fivefold increased risk of STEMI. Smoking cessation reduced this risk to a level similar to never-smokers.