Abstract
This report describes a patient with drug refractory severe chronic ischemia heart failure, atrial fibrillation with bradycardia, and left bundle branch block who had a failed implantation of a biventricular pacemaker because of a high left ventricular pacing threshold. VVI pacemaker implantation had not improved the patient's condition. MRI-guided biventricular pacemaker upgrade had been performed with a left ventricular epicardial lead at the lateral region where a 4-mm thickening during systole had been proven. After 6 months of effective resynchronization, the patient's functional class improved to NYHA II without further need of hospitalization.