Comparison of CRT and CRT-D in heart failure: systematic review of controlled trials.

Few studies have directly compared cardiac resynchronisation therapy (CRT) with combined CRT-cardioverter defibrillator therapy (CRT-D) in patients with left ventricular (LV) impairment. We performed a systematic analysis to assess the therapeutic effects of CRT and CRT-D in patients with LV impairment and heart failure.