Smoking and sex differences in first manifestation of cardiovascular disease

Background and aims: An increasing proportion of women believe that smoking few cigarettes daily substantially reduces their risk of developing cardiovascular (CV) related disorders. The effect of low intensity smoking is still largely understudied. We investigated the relation among sex, age, cigarette smoking and ST segment elevation myocardial infarction (STEMI) as initial manifestation of CV disease. Methods: We analyzed data of 50,713 acute coronary syndrome patients with no prior manifestation of CV disease from the ISACS-Archives (NCT04008173) registry. We compared the rates of STEMI in current smokers (n = 11,530) versus nonsmokers (n = 39,183). Results: In the young middle age group (<60 years), there was evidence of a more harmful effect in women compared with men (RR ratios: 1.90; 95% CI: 1.69-2.14 versus 1.68; 95% CI: 1.56-1.80). This association persisted even in women who smoked 1 to 10 packs per year (RR ratios: 2.02; 95% CI: 1.65 to 2.48 versus 1.38; 95% CI: 1.22 to 1.57). In the older group, rates of STEMI were similar for women and men (RR ratios: 1.36; 95% CI: 1.22-1.53 versus 1.39; 95% CI: 1.28-1.50). STEMI was associated with a twofold higher 30-day mortality rate in young middle age women compared with men of the same age (odds ratios, 5.54; 95% CI, 3.83-8.03 vs. 2.93; 95% CI, 2.33-3.69). Conclusions: Low intensity smoking provides inadequate protection in young - middle age women as they still have a substantially higher rate of STEMI and related mortality compared with men even smoking less than 10 packs per year. This finding is worrying as more young - middle age women are smoking, and rates of smoking among young-middle age men continue to fall.