Lower age at first myocardial infarction in female compared to male smokers

Smoking is one of the most important risk factors for myocardial infarction. Smokers usually suffer their first myocardial infarction earlier in life compared to non-smokers. This age difference seems to be greater in women than in men. The aim of this study was to examine the age and sex differences in terms of smoking in patients with first myocardial infarction who were enrolled in the Swiss National Registry of myocardial infarction, AMIS Plus.

Data of 15,711 patients admitted to an AMIS Plus hospital between 1999 and 2008 with a first myocardial infarction were analysed. Several multivariate regression, interaction and sensitivity analyses were conducted.

The mean age at first myocardial infarction was 68.5 ± 12.2 years for non-smokers and 56.6 ± 11.7 years for smokers (P < 0.001). After stratification by sex the difference between non-smokers and smokers was 10.2 years in men and 13.1 years in women. Even after adjustment for risk factors (overweight, hypertension, dyslipidaemia, diabetes), comorbidities (peripheral vascular disease, cerebrovascular disease, chronic lung disease), regular cardiovascular medication intake before admission, Killip classification and ECG on admission, male smokers were 8.7 years younger than male non-smokers at first myocardial infarction. In women, the age difference between smokers and non-smokers was 10.8 years, giving a sex-specific difference of 2.1 years (P < 0.001).

In the AMIS Plus cohort, smoking was associated with younger age at first myocardial infarction and this was much more pronounced in women. Public health campaigns should take into account the impact of smoking on premature first myocardial infarction, especially in women.