Sex differences in secondary prevention and outcomes post-myocardial infarction in Scotland

Abstract Background Sex differences in outcomes after myocardial infarction (MI) are of increasing interest. Differential receipt of evidence-based treatments may contribute to such disparities. Purpose In this study, we investigate sex differences in the burden of risk factors, in-hospital and long-term treatment and outcomes in contemporary practice in Scotland, by analysing a nationwide sample of consecutive MI admissions. Methods All MI admissions centrally recorded between 2010-2016 by Public Health Scotland were included and followed up until the end of 2021. Poisson regressions analysed in-hospital outcomes (percutaneous coronary intervention (PCI), mortality and post-discharge secondary prevention medication). Models were adjusted for age, co-morbidities and ST-elevation on the electrocardiogram. Royston-Parmar models analysed long-term outcomes (all-cause and cardiovascular mortality, major adverse cardiovascular events (MACE)) and were sequentially adjusted for confounders (age, comorbidities, secondary prevention medications). A 2:1 age and sex-matched general population were included as controls. Results Of a total 47,063 MI patients, 15,776 (33.5%) were women. They were matched with 81,641 controls free of major cardiovascular disease. Median (interquartile range) age was 64 (56-72) years for men and 69 (60-75) years for women. Obesity, hypertension and renal disease were the risk factors more prevalent amongst women, while men had higher rates of previous MI, peripheral vascular disease and atrial fibrillation. Compared to men, women were less likely to undergo PCI (risk ratio (95% confidence interval) – 0.87 (0.86-0.89)) or receive secondary prevention (0.94 (0.93-0.95)), but had similar in-hospital mortality (1.06 (0.99-1.13)), after multi-variable adjustment. Over a median follow-up of 8.4 (6.8-10.2) years, women had higher raw rates of adverse outcomes. However, after full confounder adjustment, this translated into lower risk for women of all cause-mortality 0.92 (0.89-0.95), cardiovascular mortality 0.82 (0.78-0.87) and MACE 0.92 (0.88-0.95) (Figure 1). The female survival advantage was attenuated post-MI in comparison to controls free of significant cardiovascular disease (Figure 2). Conclusions Women and men have different MI risk factor profiles. Women had overall worse crude outcome rates after MI, driven by age and comorbidities. This may have been driven further by undertreatment after MI, including PCI and secondary prevention. Urgent identification of drivers for such disparities in care is warranted in order to improve outcomes and ensure health equity.