Participants in the intervention arm will receive a digital RE-AIM-informed autonomy-competence intervention over four months. The intervention will aim to improve medication adherence by enhancing patients' autonomy, motivation, self-management confidence, and treatment competence.

Participants in the control group will receive standard routine cardiology care, including physician consultation, medication prescription, and usual counselling, without additional digital adherence support

Participants in the intervention arm will receive a digital RE-AIM-informed autonomy-competence intervention over four months. The intervention will aim to improve medication adherence by enhancing patients' autonomy, motivation, self-management confidence, and treatment competence. It will include individualized medication planning, shared decision-making, motivational counselling, adherence goal setting, structured medication education, pill-management support, symptom-monitoring guidance, problem-solving for adherence barriers, WhatsApp reminders, monthly telephonic follow-up, and reinforcement counselling. Family involvement will be encouraged where appropriate. Intervention fidelity will be monitored using delivery checklists, supervision, and periodic review.

The first primary outcome will be medication adherence (self-efficacy) in heart failure patients, measured using the Self-Efficacy for Appropriate Medication Use Scale Urdu version (SEAMS-U) and pill count adherence assessment. The Self-Efficacy for Appropriate Medication Use Scale (SEAMS) is a 13-item tool measuring patient confidence in medication adherence. It typically uses a 3-point Likert scale (1=not confident, 2=fairly confident, 3=extremely confident). Scores range from 13 to 39, with higher scores indicating higher self-efficacy.

The second primary outcome is medication adherence (objective adherence rate), will also be assessed using pill count methodology. Adherence rate will be calculated as the proportion of pills taken divided by the number of pills prescribed over the previous 30 days, expressed as a percentage. An adherence rate ≥80% will be considered adequate adherence.

The Minnesota Living with Heart Failure Questionnaire (MLHFQ) will be used. It consists of 21 items, each scored on a 6-point Likert scale ranging from 0 to 5, where 0 indicates no impact, and 5 indicates a very severe impact of heart failure on the patient's life. The total score ranges from 0 to 105, with higher scores indicating poorer health-related quality of life. The questionnaire also includes two major subscales: the physical dimension (8 items; score range 0-40) and the emotional dimension (5 items; score range 0-25), with higher scores indicating poorer HRQoL.