Physical fitness after myocardial infarction compared with clinical reference values: a SWEDEHEART registry study

Purpose The primary aim of this study was to describe physical fitness in a large real-world cohort of patients entering exercise-based cardiac rehabilitation (EBCR) after first-time myocardial infarction (MI). The secondary aim was to compare the results with clinical reference values. Methods This registry-based cohort study used data from the Swedish Web-system for Enhancement and Development of Evidence-based care in Heart Disease Evaluated According to Recommended Therapies (SWEDEHEART) post-MI registry between 2016 and 2019. Patients with first-time MI who underwent physiotherapist-led assessments of physical fitness at EBCR entry were included. Exercise capacity was evaluated by a symptom-limited cycle ergometer test and muscular endurance by a unilateral heel-rise test. Results were compared with age-stratified and sex-stratified clinical reference values. Reference values for exercise capacity were based on the Swedish Kalmar dataset, the national standard reference in Sweden since 2014, and reference values for heel-rise performance were based on a Swedish normative dataset of healthy adults. Results A total of 15 105 patients (mean age 62.5±9.1 years, 78.4% men) were included. Exercise capacity (Watt max from the exercise test) was higher in men than women across age groups, and muscular endurance declined with age, with a steeper age-related decline in women’s heel rise performance. The mean exercise capacity of the study population corresponded to 64.7±27.4% of predicted values in men and 68.4±18.9% in women. Muscular endurance averaged 78.4%±51.0% of reference values in men and 61.7%±43.2% in women. Conclusion At EBCR entry after a first-time MI, both exercise capacity and muscular endurance were substantially below age-specific and sex-specific reference values. These results underscore the importance of systematic baseline assessments and tailored rehabilitation interventions targeting both exercise capacity and muscular endurance.