Pivotal trials of cardiac resynchronization therapy: evolution to therapy in mild heart failure.

Cardiac resynchronization therapy (CRT) has traditionally been reserved for patients with left ventricular (LV) dysfunction in the setting of advanced heart failure. Early clinical trials clearly demonstrated reverse ventricular remodeling and clinical benefits following CRT in this population. More recently, with the publication of the REVERSE, MADIT-CRT, and RAFT trials, the benefits of CRT have been demonstrated in patients with LV dysfunction and mild heart failure calling into question the optimal timing for biventricular pacemaker implantation. With the expanded indications for CRT arising from these studies, significant questions remain specifically with regards to the economic impact on health care systems and to the added risk of future morbidity due to device infection and malfunction.