[Horizons and perspectives on the problem of non--responders to cardiac resynchronization therapy.]

Cardiac resynchronization therapy (CRT) has been shown as a successful strategy in the treatment of patients with heart failure and electrical dyssincrony. However, a significant proportion of implanted patients fails to respond sufficiently or in a predictable manner. Consequently, non response to CRT remains a valuable problem in clinical practice. In order to improve CRT response and long-term clinical benefits, the proper evaluation of patient's global frialty, the technology improvement, the multimodality imaging approach and the use of simple and low cost electrographic parameters (to verify effective biventricular capture and QRS narrowing) could play a important role. Therefore, the integration of various medical expertises (clinical cardiology, cardiac advanced imaging, electrophysiology) is a crucial element in order to achive the maximal benefits from this promising tecnique. In the multistep process (from patients evaluation to results verification) the follow-up even from the earliest post implantation phase, should be managed with great attention having the potential for impact the prognosis. This brief review focus the problem of non responder to CRT, giving particular attention to the different variables that may play a role (comorbilities, improvement in the tecnology of device implantation, role of multimodality imaging and electrocardiographic parameters).