Cardiac Magnetic Resonance as a Tool to Assess Dyssynchrony.

Cardiac resynchronization therapy (CRT) improves cardiac mechanics and quality of life in many patients with evidence of electromechanical cardiac dyssynchrony. However, up to 30% of patients receiving CRT do not respond to therapy. The mediator for poor response likely varies among patients; however, careful evaluation of mechanical dyssynchrony may inform management strategies. In this article, some of the methods and supporting evidence for dyssynchrony assessment with MRI as a predictor for CRT response are presented. The case is made for pre-implant assessment with MRI because of its ability to characterize scar, coronary venous distribution, and regional strain patterns.