[Atrial fibrillation and the sentinel watch.]

The Apple Watch 4 is a wearable device whose advertising launch made a lot of noise, not only for technological advances in general, but above all because the latest version is able to record an electrocardiogram. The device signals to the wearer the possible presence of atrial fibrillation, an arrhythmia that is often difficult to identify. There is also the possibility that the increased engagement of citizens causes excessive confidence in self-monitoring and in "do-it-yourself" diagnoses. Therefore medical experts are needed, who educate the user for a correct use, avoiding the risk of false positives and consequent false alarms. Currently, methodologically rigorous studies are lacking to validate the use of the device to integrate the traditional diagnostic tools.