Many mobile health applications including mobile heart monitoring applications are available on Apple App Store, and Google Play Store. However, when the user feels dissatisfied with the user interface design of the mobile heart monitoring application, it impacts user satisfaction level to the extent that the users do not use it anymore. User satisfaction level is a very important factor in usability to identify a mobile heart monitoring application which is pleasant and comfortable for continuous use. This study recruited four cardiologists in a hospital in Palembang, Indonesia for evaluating the user interface design of a mobile heart monitoring prototype called HeartM. The prototype has several features including measuring patient's heart rate and blood pressure rate, treatment record, forum, and chat to ease communication between heart patients and their cardiologist. The focus of the user interface design evaluation are on content, visual and navigation aspects. This paper contributes to user interface design knowledge and design recommendations particularly for mobile heart monitoring applications.