First report of a wearable fitness tracking device capturing a cardiac arrest

A previously healthy 37 year old man, with no risk factors, sustained a cardiac arrest whilst running a half marathon. During the event, he was using a fitness tracking device (Fitbit Surge, Fitbit Inc. San Francisco). The time and location of the arrest was determined from the Fitbit data when the pace fell to zero, indicating a lack of movement (Figure 1). Interestingly, at the time of the arrest the heart rate decreased but did not fall to zero as expected. These heart rate inaccuracies may be related to cardiopulmonary resuscitation (CPR) interference.