Aim: To evaluate the effectiveness of an artificial intelligence (AI)-assisted 12-month Health Coach-Led Digital Lifestyle Intervention (HEALDI) versus control on diffuse myocardial fibrosis and ambulatory blood pressure in individuals with hypertensive heart disease (HHD), with secondary outcomes including multi-organ health parameters, health behaviours, social support, psychological health, and health-related quality of life.

Background: The global prevalence of hypertensive heart disease (HHD) has increased approximately 1.5-fold, from 7.82 million cases in 1990 to 12.50 million in 2021, and it is now the second leading cause of heart failure worldwide. In HHD, chronic pressure overload drives fibroblast activation and interstitial collagen deposition, leading to diffuse myocardial fibrosis which is associated with cardiac dysfunction, arrhythmias, impaired coronary flow reserve, and an increased risk of sudden cardiac death and heart failure. Although diffuse myocardial fibrosis is potentially reversible, no approved anti-fibrotic pharmacological therapy currently exists. Furthermore, there is limited evidence evaluating the effectiveness of lifestyle interventions, particularly aerobic exercise, in reversing diffuse myocardial fibrosis.

Design: A parallel, single-blinded two-arm randomised controlled trial.

Method: This study is a randomised controlled trial with repeated measures, recruiting 200 physically inactive individuals with HHD from the community, including participants from Project RESET, a community-based cohort study in Singapore. Participants will be randomly allocated to either the intervention or control group.

Participants in the intervention group will receive the 12-month HEALDI intervention, which includes the HEALDI mobile application, wearable device, and remote health coaching. Participants in the control group will receive a wearable device and a basic mobile application without intervention features, used solely for data collection.

Data will be collected at baseline (upon randomisation) and at 6, 12 and 24 months. A process evaluation will be conducted using intervention engagement data. In addition, semi-structured interviews with participants and health coaches will explore perceptions of the intervention and behaviour change. A within-trial economic evaluation, from both healthcare system and societal perspectives, will be performed to assess cost-effectiveness.

Significance: This study will generate insights into the role of lifestyle modification as a complementary, non-pharmacological strategy alongside pharmacotherapy to halt or slow HHD progression, improving long-term cardiovascular outcomes.

Specific Study Aims

1. To compare the effectiveness of HEALDI on change in diffuse myocardial fibrosis, ambulatory blood pressure, with secondary outcomes including multi-organ clinical parameters (e.g. blood tests, liver and brain imaging) and patient-reported outcomes (e.g. physical activity, dietary practices, perceived stress, sleep quality, medication adherence, social support, psychological health, and health-related quality of life).
2. Examine the cost-effectiveness of HEALDI intervention.
3. Explore the perceptions of the individuals with HHD and health coaches regarding HEALDI.

Hypotheses

It is hypothesised that participants who received the HEALDI intervention, compared to the control group will have:

• Greater regression in diffuse myocardial fibrosis;
• Greater improvement in ambulatory blood pressure;
• Improved multi-organ clinical paramaters;
• Greater adoption and sustained adherence to health behaviours;
• Better quality of life;
• Lower cost to participants and hospitals.

HEALDI Intervention The HEALDI intervention is a 12-month, AI-assisted, health coach-led digital lifestyle intervention comprising a wearable device, HEALDI mobile application, health coach web portal, and administrative web portal. The system functions as an integrated platform to facilitate interaction between participants and health coaches, supporting personalised lifestyle modification.

Participants will access the HEALDI mobile application via their personal smartphones and will be provided with a wearable device that continuously collects activity and physiological data. These data, together with participant-entered health metrics (e.g., blood pressure, medication), will be synchronised to a secure cloud server and made available on the health coach portal to inform coaching sessions, including goal setting and progress review.

Certified health coaches will deliver 30-45-minute remote coaching sessions over 12 months: weekly during the first month, biweekly for the subsequent 5 months, and monthly for the remaining 6 months.

Data Analysis Data will be analysed using IBM SPSS Statistics Version 29.0, with two-tailed p<0.05 indicating statistical significance. Analyses will follow the intention-to-treat principle. Baseline categorical variables will be compared using Chi-squared or Fisher's exact tests, and continuous variables using independent t-tests or Mann-Whitney U tests, depending on normality. Linear mixed models will assess repeated continuous outcomes, and generalized estimating equations (GEE) will be used for ordinal outcomes. Descriptive analyses will summarise utilisation of the mobile app, wearable adherence, and coaching engagement.

Qualitative interviews will be audio-recorded, transcribed, and analysed thematically using Braun and Clarke's six-step framework. Two independent coders will familiarise themselves with the data, generate initial codes and iteratively refine them through discussion.

Inclusion Criteria:

• Left ventricular hypertrophy on cardiovascular magnetic resonance based on local age and sex specific criteria
• Age 40-70 years old
• Has internet access
• Owns and uses a smartphone daily
• Able to converse and comprehend the English or Chinese language

Exclusion Criteria:

• History of major cardiovascular events (MACE), which is defined as coronary heart disease death, non-fatal myocardial infarction, stroke
• Diagnosed with secondary causes of hypertension (E.g., renal causes - renal artery stenosis, chronic renal failure; endocrine causes- pheochromocytoma, Cushing's syndrome, hyperthyroidism; cardiac causes - coarctation of the aorta)
• Diagnosed with significant coronary artery disease with previous percutaneous intervention or coronary artery bypass surgeries
• Diagnosed with cardiac arrhythmias such as atrial fibrillation and frequent premature ventricular contractions
• Diagnosed with inherited/acquired cardiomyopathies (E.g., hypertrophic cardiomyopathy, dilated cardiomyopathy)
• Diagnosed with infiltrative disease (E.g., cardiac amyloid, cardiac sarcoid)
• Contraindications to Brain and Cardiac Magnetic Resonance or gadolinium contrast (E.g., renal failure- eGFR <30ml/min/m2 or documented contrast allergy; implantable devices such as cardiac pacemakers, brain aneurysms or clips, metal implants (including braces), foreign bodies in the eye; claustrophobia; end organ failure; women who are pregnant or breast-feeding)
• Any pre-existing medical conditions or disabilities that limits their participation in lifestyle interventions (E.g., Dementia)
• Individuals who have achieved the Singapore physical activity guideline of 150 minutes of moderate intensity exercise or 75 minutes of vigorous intensity exercise per week or an equivalent combination per week
• Limited life expectancy of less than 12 months
• Participating in other research projects involving behavioural therapy or changes related to physical activity

Due to the extensiveness of the clinical parameters and self-reported data, there could be exploratory analyses conducted in the future. As such, there are no current plans to share IPD.

The principal investigator will remain blinded to group allocation. Outcome assessors, including research assistants administering questionnaires and technicians performing study procedures, will be blinded to participants' assigned groups.