Smartwatch detection of atrial flutter and atrial fibrillation: when the apple falls far from the tree - case report.

Consumer wearables are increasingly used to document palpitations, but their algorithms are almost exclusively validated for atrial fibrillation (AF). We report a 70-year-old man with recurrent palpitations, no prior cardiovascular history, and controlled hypertension. A single-lead Apple Watch ECG classified sinus rhythm at 75 bpm, while a same-day 12-lead ECG revealed typical atrial flutter with sawtooth waves and regular atrioventricular conduction. After adequate anticoagulation, the patient underwent successful electrical cardioversion with 120 J and remains in stable sinus rhythm. This case highlights that AF-validated smartwatch algorithms may miss other supraventricular arrhythmias, particularly with regular ventricular response. Smartwatches can aid AF screening and symptom capture, but persistent symptoms require confirmation with standard 12-lead ECG. Future work should prioritize algorithm refinement and rigorous, post-market validation beyond AF to ensure that consumer devices transition from wellness tools to clinically reliable instruments for arrhythmia management.