ILR documentation of a syncope episode due to sinus arrest (type 1A of the ISSUE classification). (A) Heart rate trend during 42min of loop recording. Initially, the heart rate is stable at approximately 70bpm; at the beginning of the episode the heart rate increases to 100bpm, then decreases rapidly to a very low rate. (B) The expanded ECG at the time of syncope shows prolonged multiple pauses due to sinus arrest. The noise recorded during the pauses of 8s and 19s of asystole probably reflects jerking movements of the patient. The finding of initial sinus tachycardia, progressive sinus bradycardia, frequently followed by sinus arrest has been regarded as highly suggestive of a neurally mediated mechanism.