Abstract Body (Do not enter title and authors here): Background
Self-care is essential for managing heart failure (HF), yet many patients struggle with adherence to prescribed medications, low sodium diet, and daily self-monitoring of vital signs and symptoms. Commercial mobile health (mHealth) technologies offer unique opportunities for improving HF self-care, but their efficacy is underexplored.

Aim
This study aimed to assess the feasibility and preliminary efficacy of a patient-centered intervention (iCardia4HF) that integrates multiple commercial mHealth apps and devices with individually tailored text messages (TM) to promote HF self-care.

Methods
We conducted a two-arm, pilot randomized trial (NCT04262544) with allocation concealment and masking of outcome assessors. Eligible patients (adults with Stage C HF) were randomly assigned to either the control or intervention group. The control group (CG) received usual care enhanced with the provision of three consumer mHealth devices: Fitbit activity tracker and Withings Body Cardio scale and blood pressure (BP) monitor. The intervention group (IG) received the iCardia4HF program which synergistically integrates these devices with three commercial mHealth apps (Health Storylines, Withings, and Fitbit) and a program of individually tailored TM promoting HF self-care adherence. The primary outcome was medication adherence (MEMS bottle) and daily weighing adherence (Withings scale) over 12 weeks. Secondary outcomes included daily BP monitoring (Withings BP cuff) and change in self-reported self-care (SCHFI v7.2). Timestamped adherence data were transmitted from the devices to a secure digital health platform. Two-sample t-tests were performed to assess intervention effects.

Results
A total of 81 patients completed the 12-week follow up (IG=42, CG=39). Participants’ mean age was 54.7 years (SD=11.0), 81% were African American, 45% were female, 64% had HFrEF, and 85% had NYHA class II or III. There were significant differences between the IG and CG in medication adherence (85% vs 75%; d=0.5, 95% CI: 0.04, 0.96; p=0.03) and daily self-monitoring of weight (72% vs 54%; d=0.6, 95% CI: 0.15, 1.04; p=0.007) and BP (67% vs 50%; d=0.54, 95% CI: 0.08, 1.0; p=0.02) over 12 weeks. There were no significant differences between the two groups in self-reported HF self-care.

Conclusion
This pilot study provides preliminary evidence of feasibility and potential efficacy warranting further evaluation of the iCardia4HF intervention in a larger, fully powered trial with longer follow-up.