During the last decade, since its introduction, cardiac resynchronisation therapy (CRT) has become a mainstay therapy in a selected group of patients with end-stage heart failure and a left bundle branch block (LBBB) on the ECG. While the evidence for the beneficial effects of CRT in large populations has been established unequivocally,
1 it is the response in the individual which has grasped the interest of most due to the relatively large number of nonresponders. In up to 40% of patients fulfilling the current guideline criteria for CRT no clinical improvement and/or echocardiographical remodelling is observed during follow-up. Many studies have been conducted to distinguish the responders from the nonresponders in order to improve the selection of patients who would benefit from this relatively expensive treatment. …
