Smoking is the dominating modifiable risk factor in younger patients with STEMI.

AIMS:: Smoking is an important modifiable risk factor for myocardial infarction. It is unclear whether smoking habits at the time of an incident ST-segment elevation myocardial infarction (STEMI) differ across age groups and sex.

METHODS AND RESULTS:: We included patients with incident STEMI registered in the Western Denmark Heart Registry from 2005 to 2015 ( n=9914). Patients were divided into four age groups (30-49, 50-59, 60-69 and ⩾70 years) with the latter serving as reference. Smoking was the most prevalent modifiable risk factor in 30-49-year-old patients (74% vs. hypertension 15%, hyperlipidaemia 10% and diabetes 7%). The smoking prevalence decreased with increasing age, while treatment for hypertension, hyperlipidaemia and diabetes increased with increasing age. Smoking was five times (odds ratio (OR) 5.15; 95% confidence interval (CI) 4.37-6.07) more prevalent among 30-49-year-old patients with STEMI than the reference group. Differences according to sex were significant as the OR for current smoking in women was 9.88 (95% CI 6.94-14.08) compared to OR 3.78 (95% CI 3.12-4.58) in men.

CONCLUSIONS:: Despite public information campaigns and general warnings, smoking remains the most prevalent modifiable risk factor in younger patients with STEMI.