Gathering user requirements and acquiring client's trust are important tasks to be carried out in the early stage of knowledge discovery in databases (KDD) process. They have been particularly challenging within medical informatics domain due to physicians' heavy workload and distrust. In many cases, the failure to address these challenges has resulted in low user adoption and compliance rate. This paper describes the early stages of knowledge discovery on cardiovascular database in the state of Sarawak, Borneo Island. Our use of the incremental proof-of-success approach through rapid prototyping have proved to be an effective way to gather user requirements and winning trust from the local cardiologists.