Smoking in relation to ST-segment elevation acute myocardial infarction: findings from the Register of Information and Knowledge about Swedish Heart Intensive Care Admissions

OBJECTIVES: In the past few decades, clinical presentation in AMI has been reported to be changing, with milder cases and less ST-elevation myocardial infarction, the most serious form of AMI. The better outcome may be due to improved medical and interventional management, as well as more sensitive methods for detecting AMI. However, changes in risk factors have also been documented, especially lower tobacco-smoking rates. Therefore, the relation between smoking and ST-elevation AMI in a large observational cohort was analysed. METHODS: Data were derived from 93 416 consecutive patients aged 25 to 84 years and admitted to hospital between 1996 and 2004 with a first AMI. RESULTS: Tobacco smoking was more prevalent in younger patients (ie, <65 years). More than 50% of younger patients presenting with STEMI were smokers at the time of hospitalisation. After multiple adjustments, smoking was found to be an independent determinant for presenting with STEMI compared with non-STEMI. The adjusted odds ratio (OR) associated with smoking was 2.01 (99% CI 1.75 to 2.30) in younger women and 1.33 (99% CI 1.22 to 1.43) in younger men, with a significant interaction between smoking and gender. In older women and men (> or =65 years), the corresponding ORs were 1.33 (99% CI 1.20 to 1.48) and 1.14 (99% CI 1.04 to 1.25), respectively. CONCLUSION: Tobacco smoking is a major determinant for presenting with STEMI compared with non-STEMI, particularly among younger patients and among women. These results indicate that smoking is one of the major risk factors for presenting with more severe AMIs.