ILR documentation of a syncope episode due to a paroxysmal AV block (type 1C of the ISSUE classification). (A) Heart rate trend during the whole 21-min loop recording. Initially, the heart rate is stable at approximately 80bpm and suddenly falls at the time of the syncope. (B) The expanded ECG shows blocked P waves with two main pauses of 5s and 6s duration. The sinus rate increases during AV block. The noise recorded during the second pause probably reflects jerking movements of the patient. The sudden onset AV block (and ventricular pause) with concomitant increase in sinus rate suggests an intrinsic disease of the His–Purkinje system as observed in the Stokes–Adams attacks.