Abstract Background Acute coronary syndrome (ACS) and heart failure (HF) are frequent causes of hospitalisation and readmissions. A novel smartphone app-based model of care (TeleClinical Care – TCC) was developed to support patients after ACS or HF admission. Purpose This randomised control trial aimed to characterise both the intervention and clinical outcomes. The primary endpoint was the incidence of 30-day readmissions. Secondary endpoints included six-month cardiac and all-cause readmissions, mortality, major adverse cardiovascular events (MACE), cardiac rehabilitation (CR) completion, medication adherence, serum low-density lipoprotein (LDL-C), quality of life, blood pressure, body mass index, waist circumference and six-minute walk distance. Additionally, cost-effectiveness and user satisfaction were evaluated. Methods Patients were randomised 1:1 to either TCC plus usual care or usual care alone and were followed-up at six months. Intervention arm participants received the TCC app and were asked to use Bluetooth-enabled devices for measuring weight, heart rate, blood pressure and physical activity daily. Readings were automatically transmitted to the patient's smartphone and a secure web-server (KIOLA). Customisable thresholds for each parameter were defined at discharge. Abnormal readings were flagged by email to a monitoring team, who discussed management with the patient's usual healthcare providers. The app also provided educational push notifications. Results 164 patients from two hospitals in Sydney, Australia were enrolled between February 2019 and March 2020 (TCC n=81, control n=83). Recruitment ceased during the COVID-19 pandemic. The mean age was 61.5 years. 79% of patients were male. The per-patient mean percentage of days with data transmission was 64.2±27.5%. 565 alerts were received, 16% of which resulted in additional investigations, healthcare consultation or a change in management. There was no difference in 30-day readmission rate (11 readmissions in each arm). There was a significant difference in six-month readmissions, favouring the intervention (21 vs. 41 readmissions, HR=0.40, 95% CI 0.16–0.95, P=0.03), driven by a reduction in cardiac readmissions (11 vs. 25, HR=0.51, 95% CI 0.27–0.94, P=0.03). Use of TCC was associated with improved CR completion (39% vs. 18%, P=0.025) and medication adherence (75% vs. 50%, P=0.002). There was no significant difference in mortality, MACE, LDL-C, quality of life or any of the physical parameters. The average user rating was 4.56 out of 5. The study cost EUR 4015 per readmission saved. Upon modelling, it was calculated that if the number of enrolled patients exceeds 243, total expenditure will be overcome by cost savings from reducing readmissions. Conclusion The TCC model of care was feasible and safe. In this study, clinical benefits were demonstrated including a reduction in six-month readmissions, improved CR completion and improved medication adherence. Funding Acknowledgement Type of funding sources: Public hospital(s). Main funding source(s): Department of Cardiology, Prince of Wales HospitalPrince of Wales Hospital Foundation Figure 1. TCC interfaceFigure 2. Cumulative readmissions over the course of the trial