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Figure 1 The figure shows the syncopal event observed in Patient no. 1. (A) Heart rate trend during the whole 21-min loop recording. The heart rate is initially stable at 80 beats/min and then suddenly falls at the time of syncope. (B) Expanded electrocardiographic recording at the time of the syncopal event. The onset of atrioventricular block is sudden, with no change in the PP interval; the main pause lasted 12 s.