Mobile App–based Self-Monitoring of Health Behaviors in Middle-Aged Men after Myocardial Infarction: A One-Year Randomized Controlled Trial

PURPOSE: Middle-aged men after myocardial infarction (MI), particularly those at risk for heart failure, require sustained health behaviors for effective long-term self-care. This study evaluated the 1-year efficacy of a mobile app-based weekly self-monitoring program grounded in the information-motivation-behavioral skills model. METHODS: A single-blind, randomized controlled trial was conducted with 68 post-MI men who underwent percutaneous coronary intervention and had a left ventricular ejection fraction < 50%. Participants were randomly assigned to the experimental group (n = 35), who used With Your Heart, a mobile app developed for this study. The app included a weekly self-monitoring checklist with algorithm-based feedback, and participants additionally received nurse counseling during outpatient visits every 3 months. The control group (n = 33) received standard lifestyle education through a leaflet at the baseline. Outcomes were measured at the baseline, 3 months, 6 months, and 12 months. Data were analyzed using repeated-measures analysis of variance to examine group × time interactions, with Bonferroni correction applied for post hoc comparisons. RESULTS: Average age of the experimental group was 58.01 (±8.52) years and 57.35 (±9.63) years in the control group. Overall, 85.3% experienced a first-time MI, whereas 14.7% had a recurrent MI. Significant group × time interaction effects were found for health behaviors (F = 10.24, p<.001) and illness perception (F = 3.15, p = .026). The experimental group demonstrated sustained improvements in health behaviors across all follow-up points and reduced negative illness perception at 3 and 6 months. Resilience was significantly higher in the experimental group overall, although no interaction effect was observed. Depression decreased over time in both groups, with no between-group differences. CONCLUSION: Weekly app-based self-monitoring significantly improved health behaviors and favorably influenced psychological outcomes, particularly illness perception and resilience, in middle-aged post-MI men at risk for heart failure. These findings support app-based self-monitoring as a feasible digital healthcare strategy to promote lifestyle modification for at-risk patients during outpatient care.