There are many differences between cardiac resynchronization therapy (CRT) and conventional pacing therapy in terms of indications and implant techniques. Generally speaking, CRT requires implanting 3 pacing leads in heart failure patients with ventricular dysynchrony. A left ventricular lead is implanted via intravenous coronary sinus. The pacing site of left ventricle has important influence on therapy response. Sometimes open chest implant or other pacing modes are adopted to compensate the anatomical limitation of coronary sinus and its branches. In addition, the pacing sites and modes of right atrium and right ventricle are also under research to further improve CRT response.