Cigarette smoking as a risk factor for ST-elevation of myocardial infarction in young women

Background St-elevation myocardial infarction (STEMI) is the most serious form of clinical presentation of coronary heart disease. Women with STEMI have worse prognosis compared with men. The overall reduction in both incidence of STEMI and active smokers makes it unclear what role smoking continues to play as a risk factor for STEMI in the two sexes. Purpose To use the relation between current cigarette smoking and myocardial infarction to quantify the relative risk (RR) ratio of STEMI in women and men. Methods Data were derived from 11,925 consecutive patients admitted to 41 hospitals referring data to the International Survey of Acute Coronary Syndromes in Transitional Countries (ISACS-TC) registry (NCT0128776) from January 2010 to July 2018 with a first acute myocardial infarction. Outcome measures included rates of STEMI at clinical presentation as marker of larger infarctions. Estimates were obtained using logistic-regression and propensity score matching models for current versus never or former smokers. The RR was estimated using men as a reference value. Results Smokers experienced myocardial infarction (either STEMI or non-STEMI) much earlier than did non-smokers both in women (59.0±10.2 versus 68.7±11.30 years) and men (55.8±10.3 versus 63.3±11.7 years). Current tobacco smoking was more prevalent in men (50.35% vs 31.75%) and in younger patients (57.71 vs 28.81%). Among younger patients, smoking remained prevalent in men (60.11% vs 49.85%). Smoking was significantly related to STEMI (OR 1.45; 95% CI: 1.32–1.59) compared with non-STEMI. This association was noted in women (OR 1.61; 95% CI: 1.34–1.93) and men (OR 1.39; 95% CI: 1.24–1.56) and was stronger for younger (<65 years) compared with older ages (ORs 1.49; 95% CI: 1.33–1.67 vs 1.34; 95% CI: 1.13–1.59). The risk of STEMI in young women was higher than in young men (ORs 1.63; 95% CI 1.30–2.06 vs 1.45; 95% CI 1.26–1.66,). Propensity score matching analysis confirmed data. Rates of STEMI in young women and young men were 75.8% versus 64.5%, with a significant RR ratio (OR 1.15; CI 1.07–1.23) across outcomes. Conclusions Although current smoking still is an important risk factor for STEMI at all ages and sexes, it is especially relevant in younger women. Mechanisms underlying the sex difference are not related to differences in smoking behaviour. This finding is a critical reminder that physicians and society should address in rigorous tobacco-control programs in the general population with a distinctive emphasis on women, particularly in those countries where smoking among young women is increasing in prevalence.