Sudden cardiac arrest results in sudden loss of consciousness and, if the cardiac arrhythmia persists, can result in death. This video shows Christian Eriksen during the world cup of 2021. Right after exertion, he suddenly falls and is unconscious. Note that his eyes are open during the arrest. In this case, cardiac arrest is promptly recognized and he is succesfully resiscutated by defibrillation.
For more information to recognize sudden cardiac arrest see: http://dx.doi.org/10.1136/bjsports-2019-101159