Abstract: Objective: To explore the causes of death in patients with heart failure who have received cardiac resynchronization therapy(CRT).Methods: Fifty-three patients with NYHA class Ⅲ or Ⅳ heart failure who had failed to respond to standard pharmacologic therapy were treated by CRT.The routine medicine was applied after the operation.The follow-up lasted from 1 to 80 months,and the outcome was observed.Results: Seven patients died during the follow-up,5 of whom were cardiac death and 2 non-cardiac death.Cardiac death was mainly induced by deterioration of heart function and cardiac arrhythmia.Deterioration of heart function was related to primary heart disease and occurrence of atrial fibrillation.Conclusions: Causes of death in patients with CRT are varied and cardiac death is associated with the primary heart disease and the occurrence of atrial fibrillation.