Intervention protocol
Personnel in intervention practices were trained by research staff about study procedures with monthly refreshers for medical assistants. Eligible patients were mailed a letter approximately two weeks before a scheduled visit informing them about the study and inviting them to participate at their upcoming visit. Patients scheduled in a time frame too short to mail a letter were given a paper information sheet at the visit. When patients checked in, a printed sheet with a unique study identification number and barcode was automatically printed to remind medical assistants that the patient was eligible to participate. Medical assistants then asked eligible patients if they would like to participate in the study while performing routine intake and vital signs assessment. Verbally consenting patients then had vital signs obtained and, in addition, placed their fingers on a single lead AliveCor KardiaMobile ECG device (AliveCor Inc., Mountain View, CA) affixed to an iPad (Apple Inc. Cupertino, CA) to conduct AF screening. The software was configured to read the printed barcode and automatically link the ECG tracing to the participant’s study identification number. All screening was performed by practice medical assistants, not research staff.Screening results appeared on the device and included the categories: “Possible AF,” “Normal,” “Unclassified,” or “No analysis (unreadable).” Medical assistants were instructed to repeat the single-lead ECG once for “Unclassified” or “No analysis” results and then document the final result in the electronic medical record (EMR) (Epic, Verona, WI) along with other vital signs. A paper form with results was also provided for practices that routinely provided PCPs with written vital sign results. Medical assistants notified PCPs if a patient had a “Possible AF” reading. PCPs were informed that the single-lead ECG was a screening test and did not confer a definitive diagnosis of AF. PCPs managed all subsequent care including whether to obtain a 12-lead ECG during the visit. As part of the study, independent cardiologists reviewed all single-lead ECG tracings within seven days. PCPs were notified if a pre-specified actionable rhythm was identified but not addressed during the visit (Supplemental Table 