This paper presents the process of developing the design of a mobile application using Google’s Design Sprint methodology. This methodology consists of the implementation of a five-day sprint design process, including multidisciplinary team composition, problem definition, solution outline, decision making, prototyping, and a user-testing phase. The proposed digital prototype facilitates the development of the mobile application through rapid iterations and continuous improvements as a pre-implementation step. This mobile application aims to enable real-time ECG monitoring using Internet of Health Things (IoHT) technology to improve remote cardiac care in the Mexican health sector. In order to achieve this, the mobile app includes user profiles, real-time ECG monitoring, alert notifications, ECG history viewing, multiple patients connected simultaneously, and options for sharing and printing the ECGs. We designed these features to assist both patients and doctors in heart care in Mexico. In terms of data transmission, a Bluetooth connection between the mobile application and a developed wearable device carries out this task. The results obtained by the Design Sprint testing phase show that 80% of users found the interpretation of ECG data in the digital prototype intuitive, and 60% had a positive browsing experience. Currently, we are improving the mobile app design to enhance the User Interface/User Experience (UI/UX) according to the Design Sprint recommendations. Despite these ongoing improvements, both the wearable device and the mobile application are working properly, demonstrating their potential to improve heart care for patients in Mexico with the intention of expanding to other countries.