EDITORIAL Mechanical dyssynchrony in CRT: still searching for the Holy Grail

This editorial refers to ‘Dynamic relationship of left-ventricular dyssynchrony and contractile reserve in patients undergoing cardiac resynchronization therapy’†, by I. Stankovic et al., on page 48–55 The challenge of non-response to cardiac resynchronization therapy Cardiac resynchronization therapy (CRT) is a cornerstone of modern day heart failure therapy due to the consistent reduction in morbidity and mortality observed in large-scale clinical trials in patients with a severely reduced left ventricular ejection fraction (LVEF ≤35%), symptomatic heart failure, and a wide QRS complex.1 – 5 The individual benefit derived from CRT, however, may vary considerably, with a significant number of subjects demon-strating good or even excellent clinical and echocardiographic improvement and others showing little to no response.6 A reliabl