In this patient, the first sequence of ATP accelerated the arrhythmia to ventricular flutter detected in the VF zone. In some patients, the various sequences of ATP are arrhythmogenic, and transform systematically a hemodynamically stable, monomorphic VT into a fast, life-threatening VT or into VF. In a first step, one can lower the aggressiveness of the pacing sequences. Various settings can be programmed to vary the intensity of the sequences of ATP: 1) bursts are more aggressive than ramps, 2) when the pacing rate is a percentage of the tachycardia cycle, the lower the percentage, the stronger the sequence, 3) the greater the number of pacing cycles the more aggressive is the salvo, especially with a ramp, where the length of each consecutive cycle decreases, 4) the shorter is the shortest pacing interval reached by the ICD, the more aggressive is the sequence of ATP.

The salvo of ATP delivered in this patient (burst of 8 cycles at 232 ms) was not particularly aggressive. When ATP is systematically arrhythmogenic or unsuccessful (the bursts do not terminate or accelerate the tachycardia), it may be recommended to not program these therapies and to program a 5-10 J shock as first therapy instead. In this patient presenting with  arrhythmogenic right ventricular dysplasia the arrhythmia was exercise-induced. A release of catecholamines was probably the cause of the initial arrhythmia and might have contributed to the arrhythmogenic properties of the salvo of ATP. A closely followed administration of a beta-adrenergic blocker seems in order.