Abstract
Clinical trials have demonstrated improved outcomes with cardiac resynchronization therapy in patients with heart failure and electrical evidence of dyssynchrony. There has been intense effort at developing imaging markers of dyssynchrony with the aim of improved risk stratification. However, these efforts have not been fruitful to date. This article discusses mechanisms of cardiac dyssynchrony, reviews clinical data supporting resynchronization therapy, and addresses the lack of convincing evidence to support the use of noninvasive imaging measures of dyssynchrony in improving patient management.