This study randomised patients aged over 16 presenting with an episode of palpitations or pre-syncope whose underlying ECG rhythm remains undiagnosed into two groups, with one group using a smart phone based event recorder. The study aims to discover if the event recorder may allow for better and earlier diagnosis of these patients. The results for this study are available here: https://www.thelancet.com/journals/eclinm/article/PIIS2589-5370(19)30026-4/fulltext