Cardiac resynchronization therapy: current trends and future directions.

Despite the clear cut indications for cardiac resynchronization therapy (CRT) laid down by guideline forming bodies, there are numerous unresolved issues. This review article primarily focuses on the current trends in CRT and the challenges encountered in patient selection, procedure related and postimplantation patient management issues. The high rate of non-response to CRT warrants a critical appraisal of the patient selection criteria, with the role of QRS duration and use of imaging to quantify ventricular dyssynchrony being the major points of discussion. Likewise the role of CRT in relatively asymptomatic heart failure patients, those with atrial fibrillation and the benefits of providing an implantable cardioverter defibrillator backup to all CRT devices has yet to be clearly defined. The development of effective and minimally invasive surgical techniques, dependable and reproducible means for optimal pacing site localization and comparative trials on superior mode of lead positioning, pacing sites and optimized CRT programming encompassing diverse patient populations would further advance current standards of CRT. Innovative approaches to resolve these controversies and future goal directed research is needed. Development of novel, comprehensive prediction tools to identify responders to CRT and the possibility of 'leadless' pacing would be interesting futuristic prospects.