Aims: This study examined clinical factors associated with sex differences in the use of acute reperfusion therapy (fibrinolysis or primary percutaneous coronary intervention) in ST-elevation myocardial infarction (STEMI) patients, and the interaction between sex and these factors in Sweden and Canada.

Methods: Patients with STEMI in Sweden (n=32,676 from the Register of Information and Knowledge about Swedish Heart Intensive Care Admissions) were compared with similar patients in Canada (n=3375 from the Canadian Global Registry of Acute Coronary Events) for the period 2004–2008.

Results: Unadjusted vs. age-adjusted odds ratios (OR) for no reperfusion (women vs. men) were for Sweden 1.57 (95% CI 1.49–1.64) vs. 1.14 (95% CI 1.08–1.20), and for Canada 1.61 (95% CI 1.39–1.87) vs. OR 1.18 (95% CI 1.01–1.39). Sex differences persisted after multivariable adjustments (including prehospital delay, atypical symptoms, diabetes), factors for which no interaction with sex was found. Among women <60 >years, adjusting for atypical symptoms in Canada and angiographic data in Sweden made the greatest contribution to explaining observed sex differences.

Conclusions: In both countries, acute reperfusion therapy in STEMI was used less often in women than in men. Factors associated with these sex differences appear to differ between older and younger women. Targeted interventions are needed to optimize care for women with STEMI, as well as sex- and age-stratified reporting of quality indicators to assess their effectiveness.