The formative, landmark descriptions of the prevalence and risk of atrial fibrillation (AF) in the Framingham Heart Study were based on “spot” 12-lead electrocardiograms.1 In terms of surveillance, this was largely unchanged from centuries of recording an irregular pulse by palpation and required a very high frequency of sustained arrhythmia to detect AF. However, the last decade has seen a substantial increase in the potential tools available for detection of infrequent AF, including a variety of “wearable” technologies.2-6 The ready availability of both medical and consumer-based technologies for diagnosis of AF is driving a major shift in the approach from characterizing AF as a binary diagnosis—present or absent—to one on a continuum (based more on frequency of arrhythmia).7