Associations of Exercise Capacity After Myocardial Infarction with Mortality and Major Adverse Cardiovascular Events: Sex-Specific Findings from the Nationwide SWEDEHEART Cohort.

AIM: Investigate sex-specific associations between exercise capacity and the risk of all-cause mortality and major adverse cardiovascular events (MACE) after myocardial infarction (MI), using nationwide real-world data. METHODS: A prospective cohort study using the SWEDEHEART registry. Patients with an MI (2016-2020) were included. Exercise capacity (maximal workload in Watts) was assessed using bicycle ergometer testing performed before exercise-based cardiac rehabilitation, 2-8 weeks after hospital discharge. Outcomes were all-cause mortality and MACE (MI, stroke, and cardiovascular death), identified in national cause-of-death and patient registries (2016-2023). Associations between exercise capacity and outcomes were evaluated using adjusted Cox proportional hazard models. The functional form of the association was assessed using restricted cubic splines. RESULTS: There were 15,945 patients (78% men), with a median age of 64 (IQR: 56-70) years, included. During a median follow-up of 3.2 (2.3-4.3) years, 420 deaths and 948 MACE occurred. Higher exercise capacity (per 10-Watt increase) was associated with an 18% lower hazard of death in men and a 33% lower hazard in women, with a linear association for both sexes. Similarly, MACE hazard decreased by 8% in men and 18% in women per 10-Watt increase in exercise capacity, with a curvilinear association for men and linear association for women. CONCLUSION: Higher exercise capacity measured by routine clinical exercise testing was associated with lower risk of all-cause mortality and recurrent MACE, with stronger associations in women. These findings support the use of exercise capacity testing to identify patients at the highest risk.