Determinants of Functional Improvement After Cardiac Rehabilitation in Acute Coronary Syndrome

Introduction: Cardiac rehabilitation (CR) is an effective tool for secondary prevention after acute coronary syndrome (ACS). Aim: Aim of our study was to find the significant determinants of exercise capacity (evaluated with the six-minute walking test—6-MWT) and functional improvement in patients undergoing CR after an ACS. Methods: The study group included 298 patients (mean age 61.6 ± 10.2 years; males 80.2%) who, after ACS, were enrolled in CR program at Niguarda Hospital in Milan from 2015 to 2018. For all patients, we collected anamnestic, clinical and instrumental cardiological data. All patients performed a 6-MWT at the beginning (6-MWT-1) and at the end (6-MWT-2) of CR program. Δ meters were used to represent functional improvement. Results: Multiple linear regression models were carried out for 6-MWT-1, 6-MWT-2, Δ meters and % Δ meters. Standardized regression coefficients showed that age (β = − 0.237; p < 0.001), BMI (β = − 0.116; p = 0.006) and heart rate (β = − 0.082; p = 0.040) were determinants of exercise capacity (6MWT-1 and 2), whereas age (β = −.231; p = 0.004), sex (β = − 0.187; p = 0.008) and BMI (β = − 0.164; p = 0.022) were determinants of functional improvement (Δ meters). Conclusions: Our data showed that functional improvement after CR in ACS patients is mainly related to non-cardiological variables. Instead it is related to intrinsic factors, both modifiable (BMI) and non-modifiable (age, sex).