<qa>  What is the aim of the study?The aim of this study is to investigate if imaging guided optimal left ventricular LV lead placement improves the response rate to cardiac resynchronization therapy CRT. Consecutive patients meeting the standard criteria for CRT are included in a prospective, double-blinded, randomized trial to LV lead positioning either 1 guided by cardiac imaging using echocardiography, single-photon emission computed tomography, and visualization of cardiac venous anatomy cardiac computed tomography CT, venography to target an epicardial vein at the site of latest mechanical activation without scar tissue or 2 using standard LV lead placement. 