Development of strategies for guiding cardiac resynchronization therapy.

This article illustrates the highly interesting possibilities of cardiac resynchronization therapy (CRT) yet also discusses several problems for optimal implementation. The authors have presented possible strategies to improve CRT by designing and using better measurements of mechanical dyssynchrony or discoordination, leading to better patient selection. In addition, application of CRT can be improved by developing techniques to reach the optimal pacing site(s) easier and algorithms for easier programming of optimal atrioventricular delay and interventricular interval. Also, application of CRT in patients with less severe heart failure deserves further attention. Finally, the mechanism of ventricular interaction may open new fields of application of left ventricle-based pacing in patients who have heart failure, even with a narrow QRS complex.