I’ve recently seen a spate of reports of individuals whose “life has been saved” by the Apple Watch. Reading these articles generally reveals that it was actually the onset of atrial fibrillation that was detected. While that is very important and promptly addressing atrial fibrillation can allow treatment to prevent devastating strokes, I have yet to see true evidence of saving lives. Until they build in a defibrillator, I suspect most of the health benefits from this type of remote monitoring will be identification of bradycardia, atrial fibrillation and other cardiac arrhythmias. A large study on the value of arrhythmia monitoring with the watch, The Apple Heart Study, has had its rationale and design published but the results remain to be reported. Versions 4 and 5 of the Apple Watch can take a single lead EKG, but I have not seen any reports where changing morphology is used to detect hyperkalemia or QT prolongation or ischemia. There is a paper in preprint on using the Apple Watch to take standard and precordial leads, by placing it on the leg or changing the finger used to record. It remains to be seen if this rather cumbersome approach has practical utility in a busy medical practice.