A 76-year-old patient presented to our regional hospital in Queensland Australia with COVID-19-related symptoms on a background history of heart transplantation in 2007 (no documentation available). Her ECG was first interpreted as atrial fibrillation (AF) by the computer and admitting doctor. Commencement of treatment with anticoagulant was considered. On a closer look, however, sinus rhythm at a rate of 65 beats per minute was evident, but increased atrial activity with two distinct p waves on the rhythm strip was noted. Only one of the two atrial impulses was conducted to the ventricles, which is suggestive of a biatrial heart transplant. 

Incorrect interpretation of atrial fibrillation can result in unnecessary investigations and potentially harmful treatment. According to Lindow et al. (1) in almost 10% of ECGs with a computer-based diagnosis of atrial fibrillation or atrial flutter, the diagnosis was incorrect. In almost half of the cases, the misdiagnosis was not corrected by the overreading physician. Some of those patients received inappropriate anticoagulant treatment because of misdiagnosis. Furthermore, atrial fibrillation in heart transplants can be associated with graft rejection (2), therefore misinterpretation of the ECG as AF could have led to more unnecessary investigations/treatment.