Several multicenter randomized clinical trials have established cardiac resynchronization as a safe and effective way to treat heart failure patients. This is reflected in the Focus Update of the European guidelines that describes a class IA indication in patients with NYHA class II-IV heart failure with LVEF≤35% and QRS≥120 ms (NYHA III/IV) or ≥150 ms (NYHA II). If applied in clinical practice, this patient selection results in ineffective treatment in about one third of patients implanted. Since the pathophysiological basis of the disease, a disorganized electromechanical function in patients with left bundle branch block (LBBB), is amenable to analysis with imaging methods, imaging has always played an important role in patient selection. None of the parameters used proved to be reliable for the prediction of cardiac resynchronization therapy success in the multicenter PROSPECT trial. Following the publication of PROSPECT in 2008, several new studies using echocardiography and cardiac magnetic resonance imaging were published. New publications are evaluated and analyzed in the context of earlier ones.