BRIDGE Trial: Embedding Consumer-grade mHealth Technologies Into Cardiac Rehabilitation

Phase II Cardiac Rehabilitation (CR) is an evidence-based secondary prevention program for patients with cardiovascular disease (CVD).The core components of comprehensive CR are well-established and include patient assessment, exercise training, physical activity (PA) promotion, health education, nutritional counseling, psychological support, and CVD risk management. Phase II CR programs generally offer three sessions per week in an outpatient center - known as center-based CR (CBCR) - and supplemental healthy lifestyle behaviors are encouraged in patients' daily living environments. Despite strong evidence supporting the effectiveness of CBCR, its impact is constrained by four main barriers: 1) patients often fail to maintain adequate physical activity on non-CR days; 2) many patients fail to attend all prescribed CR sessions while others prematurely discontinue the program; 3) many CBCR programs are exercise-centered, offering minimal attention to other core components (e.g. risk management); and 4) reach remains limited, with poor adherence to home-based recommendations. Data shows that up to 86.5% of CR participants fail to meet guideline-recommended weekly PA targets and remain largely inactive on non-CR days. Also, only 26.9% of participants completed the 36-session course of CBCR, while 56.7% attended at least 25 sessions - a threshold associated with significant health benefits. Additionally, standardized educational programs for CR participants are lacking across many healthcare systems, and it is reported that a lack of CR knowledge and low self-efficacy are significant barriers to CR adherence and PA regimen adherence. Many CR programs do not fully deliver all components of comprehensive CR, with a tendency to emphasize exercise training while providing less consistent attention to diet, medication adherence, and other risk management components. Innovative and scalable strategies that extend patient support beyond the clinic and reinforce behavior change are urgently needed to maximize the clinical benefits of CBCR.

Mobile health (mHealth) technologies, such as smartphones, apps, text messages, wearables, and other commercially available connected health devices, have gained popularity in recent years. These mHealth tools offer a promising adjunctive approach to traditional CBCR programs, helping overcome some of the existing challenges. Mobile apps and wearable activity trackers can facilitate more frequent self-monitoring in the community and encourage positive health behaviors, including self-management of CVD. Evidence shows that text messages (TMs) are associated with improvements in PA and medication adherence among different populations and support self-management of chronic conditions. Our recent systematic review published in The Lancet Digital Health demonstrates that provision of exercise-based CR at home facilitated by mHealth technologies is associated with significantly greater benefits in functional capacity and other health outcomes compared with usual care. These findings confirmed that mHealth can effectively enable patients to engage in CR-related behaviors outside formal outpatient settings. However, very few studies have evaluated mHealth as an adjunct to CBCR to extend behavioral support in people's daily living environments. The question of whether mHealth tools can meaningfully augment the effectiveness of CBCR remains largely underexplored. Additionally, prior studies have mainly tested research-developed apps that are not commercially available, thus limiting scalability and potential for real-world implementation. The effect of tailored theory-based TM programs combined with widely used commercial mHealth tools among CBCR participants remains underexplored.

To address these gaps, our study team has developed an mHealth intervention (BRIDGE) that integrates commercially available mHealth apps (Fitbit app and Withings app) and connected devices (Fitbit tracker, Withings BP and weight monitor) with individually tailored TMs selected from a study-developed TM library. BRIDGE intervention will augment CBCR by targeting multiple CR components, including exercise training, PA, heart-healthy diet, weight management, and CVD risk management.

The goal of the proposed project is to evaluate the feasibility, acceptability, and preliminary efficacy of the BRIDGE intervention in improving exercise capacity and self-reported health outcomes through a randomized controlled trial (RCT). A total of 30 CR participants will be recruited and randomized to one of two treatment groups: (1) CBCR alone, (2) CBCR + BRIDGE intervention.

Participants randomized to the control group will receive standard outpatient CBCR at UI Health with no additional study-delivered mHealth intervention. The CBCR program at UI Health is a structured, medically supervised secondary prevention program for patients with qualifying cardiovascular conditions. It includes individualized aerobic and resistance exercise training, clinical monitoring during exercise sessions, education on heart disease and risk factor management, counseling to promote healthy lifestyle behaviors, and support for long-term adherence to prescribed treatment and self-care recommendations.

Participants are encouraged to attend up to 36 supervised sessions over \~12 weeks. In addition to supervised exercise, CBCR includes education related to cardiovascular disease self-management, physical activity, healthy eating, weight management, lipid control, blood pressure management, smoking cessation, stress reduction, and other risk factor modification strtegies.

Other: CBCR

Participants randomized to the intervention group will receive BRIDGE in addition to the standard CBCR program at UI Health. BRIDGE is a multimodal mHealth intervention designed to extend behavioral support beyond clinic visits through mobile app- and device-based self-monitoring, feedback, and individually tailored text messages promoting healthy lifestyle behaviors (e.g. physical activity, heart healthy diet, and medication adherence).

Other: CBCR · Behavioral: BRIDGE mHealth intervention

The CBCR program at UI Health is a structured, medically supervised secondary prevention program for patients with qualifying cardiovascular conditions. It includes individualized aerobic and resistance exercise training, clinical monitoring during exercise sessions, education on heart disease and risk factor management, counseling to promote healthy lifestyle behaviors, and support for long-term adherence to prescribed treatment and self-care recommendations. Participants are encouraged to attend up to 36 supervised sessions over \~12 weeks.

Description: The intervention includes three commercially available mHealth apps and devices: Withings Body Composition weight scale, Withings BP monitor, and Fitbit Charge 6 activity tracker along with their companion mobile apps. Each app incorporates behavior change tools that support daily self-monitoring, feedback, and reminders across key cardiac rehabilitation domains, including physical activity, weight and blood pressure management, and cardiovascular risk factor reduction. Participants will also receive up to five individually tailored text messages per week throughout the intervention period. Messages will be individualized based on (1) patient responses to validated questionnaires administered at baseline and (2) patient-generated health data from the app/devices. Messages will target physical activity, healthy eating, weight management, blood pressure control, and cardiovascular risk reduction.

Time frame: * Baseline; * End of the CBCR program, an average of 12 weeks

Peak metabolic equivalents (METs) is a valid, clinically meaningful, and widely accepted measure of functional capacity in patients with CVD and in CR settings. It's found that peak functional capacity measured in METs is the strongest predictor of mortality risk in both normal subjects and patients with CVD. Each one MET increase is has been associated with 25% reduction in all-cause mortality among CR patients.

Peak METs will be generated by the clinic's telemetry system (cardiline) during graded exercise test (GXT), using workload estimates derived from treadmill speed and grade. Peak METs are routinely used in the CR clinic to guide individualized exercise prescription.

Time frame: * Baseline; * End of the CBCR program, an average of 12 weeks

Systolic blood pressure (SBP) and Diastolic blood pressure (DBP) will be measured at the clinic and reported in the patient's chart (EMR).

Time frame: * Baseline; * End of the CBCR program, an average of 12 weeks

BMI will be used to measure weight management and body composition.

Time frame: * Baseline; * End of the CBCR program, an average of 12 weeks

Depression will be assessed by the Patient Health Questionnaire-9 (PHQ-9). PHQ-9 is a reliable and valid measure to screen and measure the level of depression. It has been extensively tested in various populations with excellent psychometric properties (Cronbach's α 0.86-0.89). The total score ranges from 0 to 27, with a higher score indicating a more severe level of depression.

Time frame: * Baseline; * End of the CBCR program, an average of 12 weeks

Health related quality of life (HRQoL) will be assessed with the Medical Outcomes 36-Item Short Survey (SF-36). SF-36 has been used extensively in CR studies, and its psychometric properties have been tested among patients with CVD. The 36 items are divided into 8 subscales: Physical Functioning, Roles Limitations due to Physical Problems, General Health Perceptions, Vitality, Social Functioning, Role Limitations due to Emotional Problems, General Mental Health, and Health Transition. Items within each subscale are totaled to yield a summed score for that subscale. Each summed score ranges from 0 (negative health) to 100 (positive health).

Time frame: * End of the CBCR program, an average of 12 weeks

Percentage of completed CR sessions over the prescribed sessions at the end of the study.

Time frame: From date of randomization until the end of the CBCR program, an average duration of 12 weeks

Average number of steps and moderate-to-vigorous physical activity (MVPA) minutes per day will be assessed with Fitbit - a valid wrist- based monitor for patients in the intervention group. All time-stamped activity and wear-time data will automatically be transferred via participants' phone to the iCardia server.

Activity Questionnaire short form (IPAQ-SF) for patients in both the intervention group and control group.

Time frame: * Baseline; * End of the CBCR program, an average of 12 weeks

Self-reported physical activity will be assessed by the International Physical Activity Questionnaire short form (IPAQ-SF) for patients in both the intervention group and control group. The IPAQ-SF is a 9-item form that records the activity of four intensity levels: 1) vigorous-intensity activity such as aerobics, 2) moderate-intensity activity such as leisure cycling, 3) walking, and 4) sitting. The correlation between the IPAQ-SF overall scale and any index never reached the standard of 0.50.

Time frame: * Baseline; * End of the CBCR program, an average of 12 weeks

Mediterranean Diet adherence screener (MEDAS) is a 14-item questionnaire. MEDAS assesses the participants' Mediterranean diet adherence. The Mediterranean diet is a cardioprotective eating pattern that emphasizes whole, minimally processed foods.The Mediterranean diet has been shown to offer significant health benefits for patients with cardiovascular and cerebrovascular conditions, certain cancers, type 2 diabetes, and cognitive decline. It is a valid (ICC =0.692, Pearson r = 0.573) and low-burden instrument suitable for clinical and research use. MEDAS will be used to evaluate and generate TMs targeting nutrition. The overall score of Mediterranean Diet adherence screener (MEDAS) ranges from 0 to 14, with a higher score indicating healthy diet adherence.

Time frame: * Baseline; * End of the CBCR program, an average of 12 weeks

Adherence to Refills and Medication Scale (ARMS) is a 12-item questionnaire. ARMS assesses behaviors related to prescription and medication use. This tool has demonstrated strong reliability (Cronbach's α = 0.814) and validity (Spearman's ρ =-0.651, P \< 0.01), including in populations with limited health literacy. ARMS will be used to evaluate and generate TMs targeting CVD risk management (i.e., medication adherence).

Time frame: * Baseline; * End of the CBCR program, an average of 12 weeks

The Coronary Artery Disease Education Questionnaire Short Version (CADE-Q SV) assesses knowledge of coronary artery disease and cardiac rehabilitation (CR), which is associated with adherence and completion of CR. It includes 20 items across five core CR domains: medical condition, risk factors, exercise, nutrition, and psychosocial risk. The CADE-Q is one of the few validated tools for tailoring patient education in CR and has demonstrated acceptable reliability (Cronbach's alpha = 0.65 - 0.77) and validity. The overall score ranges from 0 to 20, with a higher score indicating better knowledge of coronary artery disease.

Time frame: * Baseline; * End of the CBCR program, an average of 12 weeks

Withings BP monitoring adherence, defined as the % of days patients measured their BP over the study period. It will be assessed with time-stamped data transmitted to our study server (iCardia) from the Withings BP cuff whenever a patient performs a measurement.

Time frame: * Baseline; * End of the CBCR program, an average of 12 weeks

It is defined as the % of days patients recorded their weight over the study period. Weighing adherence will be assessed via time-stamped data automatically transmitted from the scale to the iCardia server whenever a patient performs a measurement.

Time frame: * Baseline; * End of the CBCR program, an average of 12 weeks

Cardiac Self-efficacy Scale (CSES) is a 13-item questionnaire that evaluates patients' confidence in their ability to maintain physical functioning and control symptoms related to CHD. It encompasses two dimensions: patients' confidence that they can maintain functioning (five items) and that they can control symptoms (eight items). Its reliability and validity have been well established among patients with CHD. CSES will be used to evaluate patients' cardiac self-efficacy and generate TMs targeting nutrition and CVD risk management.

BRIDGE Trial: Embedding Consumer-grade mHealth Technologies Into Cardiac Rehabilitation as a Model for Chronic Disease Management