We have been developing a new diagnosis tool for cardiac arrhythmia. Our clients are expert cardiologists. They can use our Mobile App with a Smartphone or Tablet, easily and cost-efficiently. The App records the beeps of a heart rate monitor or takes a picture of the printout of an electrocardiogram (ECG), communicates with a server, and displays the result of the calculations as decision support for the medical expert.Depending on the diagnosis of the medical expert either a long-term treatment with drugs or an operation follows. The correct diagnosis and proper treatment implies an increased life quality and a reduction of unnecessary drug side effects (for patients); avoidance of legal disputes and higher success rates (for doctors); reduced costs (for health insurance companies); and an increase in the number of profitable procedures (for providers of ablation technology). Alas, the misdiagnosis rate of expert cardiologists and of competing diagnosis tools so far is high. Studies report success rates of 50%. We showed in a peer-reviewed study that our success rate is almost 90%. We have received preliminary feedback from cardiologists in hospitals that our prototype works well and that they want to use it in their daily work. The diagnosis is a daily task for cardiologists in Europe, with an estimated number of one million diagnoses per year.We have unique selling points and market entry barriers for competitors: our approach is based a) on a deep understanding of electrophysiological processes and the integration of the team into clinical practice and b) on sophisticated mathematical algorithms that are not easy to reimplement and further enhanced in the ERC Consolidator Grant MODEST and c) on a comfortable IPR situation (granted patent).With isitFlutter we want to perform a multi-center test and adapt our product accordingly, evaluate competition and IPR, and extend our contacts with future customers, investors, and players in the market.