An unusual cause for inappropriate defibrillator shock

A 50-year-old lady with dilated cardiomyopathy and scar VT underwent single chamber implantable cardioverter-defibrillator (ICD, Medtronic Ltd, Evera XT VR, DVBB2D1) implantation 2 months back. A Sprint Quattro secure 6947 DF1 dual coil lead was placed at RV apex. Now, she presents with an episode of ICD shock while having breakfast. The device interrogation shows a 36 J shock in VF zone (Fig 1A). However, the stored electrograms (EGM) reveal distinct QRS complexes in the far-field EGM; hence, suggesting the shock is related to oversensing. Fig 1B shows 2 panels of another recent episode. Fortunately, there was aborted therapy as there was intermittent resolution of the oversensing. The lead impedance was normal but threshold was high. Is it possible to predict the reason for the oversensing from the EGM and how to troubleshoot?