Objectives To investigate for trends in sex-related differences in the invasive diagnostic–therapeutic cascade in a population of patients with acute coronary syndromes (ACS).

Design A nationwide cohort study.

Setting Administrative and clinical registries covering all hospitalisations, invasive cardiac procedures and deaths in the Danish population of 5.6 million inhabitants.

Participants We included 52 565 patients aged 30–90 years who were hospitalised with a first ACS from January 2005 to November 2011. Follow-up was 60 days from the day of index admission.

Main outcome measures Diagnostic coronary angiography, percutaneous coronary intervention or coronary artery bypass within 60 days of index admission.

Results Women constituted 36%, were older, had more comorbidity and were less likely to be admitted to a hospital with cardiac catheterisation facilities than men. Mortality rates were similar for both sexes. Diagnostic coronary angiography was performed less frequently on women compared with men, both within 1 day (31% vs 42%; p<0.001) and within 60 days (67% vs 80%; p<0.001), yielding adjusted female–male HRs of 0.83 (0.79–0.87) and 0.86 (0.84–0.89), respectively.Among the 39 677 patients undergoing coronary angiography, non-obstructive coronary artery disease was more frequent among women than men (22% vs 9%; p<0.001). Women were less likely to undergo percutaneous coronary intervention (58% vs 72%; p<0.001) and coronary artery bypass (6% vs 11%, p<0.001) within 60 days than men, yielding adjusted HRs of 0.96 (0.92–0.99) and 0.81 (0.74–0.89), respectively. The sex-related differences were not attenuated over time for any of the invasive cardiac procedures (p values for trend >0.05).

Conclusions In this nationwide study, men were more likely to undergo an invasive approach than women when hospitalised with a first ACS—a difference persisting from 2005 to 2011. Future studies should focus on the potential mechanisms behind this differential treatment.