Background
Exercise has shown significant health benefits in patients with heart failure (HF), including reduced hospitalizations and cardiovascular mortality. However, it also poses risks such as angina, arrhythmias, and syncope—especially during unsupervised sessions. Access to supervised cardiac rehabilitation (CR) remains limited, particularly among racial and ethnic minority groups, making exercise safety a critical concern in this population.

Objective
To address this challenge, our team has developed a prototype wearable biosensor to collect sweat and measure its biomarkers during exercise. This proof-of-concept study aims to determine whether serum biomarkers that rise during exercise (e.g., CRP and norepinephrine) are detectable in sweat and correlate with serum concentrations. Ultimately, we aim to evaluate whether sweat biomarkers can be used to predict high-risk exercise responses in HF patients and inform safer, personalized exercise prescriptions. We hope to explore whether sweat CRP correlates with adverse events (e.g., angina, arrhythmias, syncope) and whether sweat NE levels align with the ventilatory threshold (VT1) to identify exercise intensities associated with increased risk.

Methods
Ten HF patients undergoing cardiopulmonary exercise testing (CPET) have been enrolled. During CPET, sweat samples (mid-, post-, and total exercise) and blood samples (pre-, mid-, and post-exercise) are collected simultaneously. Telemetry ECG is monitored, and participants report perceived exertion (RPE) in their pre- and post-exercise symptom questionnaires. Sample analyses will assess the presence and concentration of sweat biomarkers, their correlation with serum levels, and their associations with CPET parameters and clinical symptoms. CRP concentrations will be measured using high-sensitivity ELISA, while NE levels will be quantified using HPLC with electrochemical detection. Correlations will be analyzed using Pearson or Spearman coefficients.

Results & Conclusions
Data analysis is ongoing. If successful, this study may establish a novel, non-invasive method to monitor exercise safety in HF. If validated, this wearable biosensor could enhance the safety of home-based CR, increase accessibility for underserved populations, and ultimately reduce morbidity and mortality in all patients with heart failure.