We report a patient with heart failure who received a cardiac resynchronization therapy defibrillator implant and suffered from wide QRS complex tachycardia and repetitive shocks from his defibrillator. Several episodes of ventricular tachycardia were induced by inappropriate defibrillator shocks for slow atrial flutters with one to one ventricular conduction. We performed atrioventricular node ablation and successfully eliminated the inappropriate shocks and improved biventricular capture.