T wave pacing inducing electrical storm and multiple shocks in an ICD-recipient: a novel complication of the automatic gain control function.

Implantable cardioverter-defibrillator (ICD) is highly effective in treating life-threatening ventricular arrhythmias, but it can also have proarrhythmic effect in some cases. We report the case of a 72 years old patient with an ischemic cardiomyopathy in whom an ICD was implanted for a poorly tolerated ventricular tachycardia (Profiles MD-Ventritex). Forty-eight hours after implantation, the patient suddenly received 15 successive shocks. ECG tracings and intracardiac EGM showed the presence of several VT episodes, all induced by the antibradycardia pacing of the ICD: the automatic gain control function of the device failed to detect ventricular premature beats in this patient, leading to a bradycardia pacing falling on the T wave and inducing multiple VTs and shocks.