Mechanical dyssynchrony in congestive heart failure: diagnostic and therapeutic implications.

Myocardial imaging has been successfully applied to the evaluation of patients with heart failure, particularly identifying candidates who are likely to respond to cardiac resynchronization therapy (CRT). Recent studies have shown the benefits of CRT in heart failure patients with depressed ejection fraction (EF) and a narrow QRS complex, albeit in a small number of patients, and without a placebo arm. In addition, few reports have noted the presence of pathophysiologically relevant mechanical dyssynchrony in patients with heart failure and normal EF. Collectively, these data support the need for a better understanding of cardiac function/dysfunction and its treatment in these patient groups.