ObjectivesTo assess the differences in the management and prognosis of acute coronary syndrome in men and women who were admitted to hospital for acute coronary syndrome.DesignCross sectional study.SettingDischarge data from Swiss hospitals linked at the hospital and patient levels.Participants224 249 adults (18 years and older) were admitted to hospital for acute coronary syndrome between 1 January 2009 and 31 December 2017 in any Swiss hospital, of which 72 947 (32.5%) were women. People who were discharged against medical advice were excluded.ResultsWomen admitted to hospital with acute coronary syndrome were older than their male counterparts (mean age 74.9 years (standard deviation 12.4)v67.0 years (13.2)). Irrespective of acute coronary syndrome type, women were less likely to undergo diagnostic procedures, such as coronary angiography (adjusted odds ratio 0.79 (95% confidence interval 0.77 to 0.82) for non-ST-segment elevation myocardial infarctionv0.87 (0.84 to 0.91) for ST-segment elevation myocardial infarction)) and ventriculography (0.84 (0.82 to 0.87)v0.90 (0.87 to 0.91)). Women were also less likely to receive treatments, such as percutaneous coronary intervention (0.67 (0.65 to 0.69)v0.76 (0.73 to 0.78)) and coronary artery bypass graft (0.57 (0.53 to 0.61)v0.79 (0.72 to 0.87)). Women had a poorer prognosis than men, with a higher likelihood of healthcare related complications (1.10 (1.06 to 1.15)v1.14 (1.09 to 1.21)) and of a longer hospital stay (1.24 (1.20 to 1.27)v1.24 (1.20 to 1.29)). In non-adjusted models, the likelihood of death in hospital was higher among women (odds ratio 1.30 (95% confidence interval 1.24 to 1.37) for non-ST-segment elevation myocardial infarctionv1.75 (1.66 to 1.85) for ST-segment elevation myocardial infarction), but the association was reversed for ST-segment elevation myocardial infarction (adjusted odds ratio 0.87 (0.82 to 0.92)) or was non-significant for non-ST-segment elevation myocardial infarction (1.00 (0.94 to 1.06)) after adjustment for confounding variables. The main effect modifier was age: younger women were more likely to die than men of the same age and older women were less likely to die than men of the same age. For example, women who were younger than 50 years had a 38% increased likelihood of dying compared with men of the same age range (adjusted odds ratio 1.38 (1.04 to 1.83)).ConclusionsSex inequalities were reported in the management of heart disease in this population of patients from a high income country with good healthcare coverage. These differences affect mortality and morbidity, especially in younger women. Efforts are needed to overcome these inequalities, including educational programmes aimed at healthcare professionals.