Characteristics that Predict Response After Cardiac Resynchronization Therapy

Purpose of Review Cardiac resynchronization therapy (CRT) is an established modality for treating heart failure. However, one-third of patients do not respond and it is increasingly recognized that response is not binary and we should be aiming for "best response". This review looks at factors predicting response and remodelling and highlights areas where we may improve both the proportion of responders but also maximize response in an individual. Recent Findings We review the clinical characteristics predicting response including structural and electrical remodelling and discuss areas of debate. We examine the evidence supporting the recently described move from anatomical-based placement of the left ventricular (LV) lead to an electrical approach with intra-operative electrical mapping and targeting of late activating regions of the LV. Finally, evidence for electrocardiographically guided post-implant programming, aiming for the narrowest paced QRS, is discussed. This includes the increasing use of atrioventricular and interventricular delay optimization and the use of newer algorithms and methods (Sync-AV, Adaptiv-CRT, Multipoint pacing, etc.) for achieving the best response. Recent data supports a tailored, individualized approach to patient selection, LV lead placement and programming to get the best response from CRT.