Case report
A 70-years-old man with a ischemic cardiomyopathy underwent ICD implant at an outside institution for primary prevention of sudden cardiac death three years ago. The ICD was a Medtronic Maximo II VR with a dual-coil VVI ICD lead. Two weeks ago the patient experienced a shock. The electrocardiography showed NSR (Figure 1). Device interrogation demonstrated that the stored intracardiac electrograms (EGMs) of the events are shown in Figures 2-3. The analysis of the episode revealed a sudden change to very rapid and irregular myocardial activity with EGM alternans that reach VF zone and a shock is delivered that restores sinus rhythm (Figure 3 ).Chest X-ray and fluoroscopy showed the active ICD lead was in the coronary sinus (Figure 4). There was no ventricular capture with pacing from ICD (Figure 5).This could only be explained by sensing of atrial signal during an acute AF in the ICD lead, probably due to inappropriate lead implantation to the coronary sinus during the first procedure. The patient has been treated with new single coil active ICD lead implantation to the right ventricule and old ICD electrode left in place (Figure 6).