Pacemaker therapy for antibradycardia support and cardiac resynchronization for amelioration of congestive heart failure have evolved technologically and application these therapies in different patient populations has been studied extensively. This chapter reviews new indications for cardiac resynchronization therapy (CRT), and application of CRT in patients with atrial fibrillation and patients with right bundle branch block. Strategies to improve response to CRT by echocardiographic screening of candidates as well as schemes to improve response to CRT by alteration of atrioventricular and interventricular timing sequences as well as newer lead and pulse generator technology are reviewed. New information on the potentially deleterious effect of right ventricular pacing and strategies to minimize this are reviewed.