Pacemakers are mainly used to treat slow arrhythmias, but they can also be used for the treatment of heart failure, as follows: 1) defibrillation pacemakers, or ICDs, which can treat and prevent heart failure by treating ventricular fibrillation; 2) triple-chamber pacemakers, or CRTs, which can synchronize left and right ventricular contractions to treat intractable heart failure. If the QRS wave width exceeds 0.12s and the patient is in sinus rhythm, and if the effect of drug therapy is not satisfactory, then this pacemaker can be considered for treatment.