Summary

Heart failure (HF) is a cardiovascular condition where the heart cannot pump blood effectively, leading to disabling symptoms of dyspnea, fatigue, low exercise tolerance, and frequent hospitalizations. Managing HF is challenging, as it often coexists with several comorbidities related to cardiovascular- and brain-health (e.g., hypertension, dyslipidemia, cognitive impairment). Physical activity (PA) programs represent a promising adjuvant to pharmacological treatments to improve patients’ functional capacity, reduce their symptoms, and facilitate long-term PA maintenance as patients’ exercise tolerance improves. However, few (<20%) patients with HF attend and adhere to traditional structured exercise programs such as cardiac rehabilitation. In response, the STEP-IN trial aims to develop and evaluate an individualized, accessible, and digitally supported step-based PA intervention.

This two-arm, single-blind multicenter randomized controlled trial will enroll 200 adults with HF with reduced (≤40%) or mildly reduced ejection fraction (41-49%) and a II or III NYHA functional class. They will be randomized 1:1 to a 9-month step-based PA intervention or enhanced usual care. The intervention will leverage wearable devices and a personalized online platform alongside behavior change methods to progressively increase participants’ daily step count (volume) and step cadence (intensity), with increments individually planned every 2 weeks. The primary outcome is the change in functional capacity measured with a six-minute walk test from baseline to 9 months. Secondary clinical, mechanistic and behavioral outcomes include HF-related symptoms and limitations (Kansas City Cardiomyopathy Questionnaire), systemic inflammation (blood-based inflammatory biomarkers, e.g., high-sensitivity C-reactive protein), and PA and steps metrics (Stepwatch and Matrix accelerometers). Changes in heart- and brain-health will also be explored using echocardiography and neuroimaging.

Positive findings will demonstrate improvements in functional capacity and PA levels, and reductions in HF-related symptoms and limitations, and systemic inflammation. If proven effective, the scalable nature of STEP-IN may facilitate its integration into routine clinical care.