Sample 24-hour ambulatory ECG recordings in the Group A and B. The 24-hour ECG recording revealed a number of exercise-provoked VPCs (n = 51) occurring solely above the heart rate of 90 bpm in a typical CPVT patient from group A. In a patient from group B, VPCs (n = 8 042) occurred also in resting conditions. The number of VPCs per hour is indicated by gray bars. The maximal heart rate per hour is shown by the curves. ECG = electrocardiogram, VPC = ventricular premature complex, bpm = beats per minute.