Patient population
Between December 2000 and December 2017, 170 consecutive DCM patients received an implantation of an implantable cardioverter-defibrillator (ICD) or cardiac resynchronization therapy with defibrillator (CRT-D) for primary or secondary prevention of VTAs in Hokkaido University Hospital. Patients were diagnosed as DCM when they satisfied the following criteria: (1) absence of significant coronary stenosis, (2) abnormal LV function (reduced LVEF <50% and dilation), and (3) exclusion of other cardiac and systemic disorders. After exclusion of patients with short follow-up/lost to follow-up, no follow-up echocardiographic data, and no follow-up record of ICD/CRT-D cases, 136 DCM patients were recruited in this study. According to the presence or absence of RR-NSVT, 68 patients without RR-NSVT were classified as the RR-NSVT (-) group and 68 patients with RR-NSVT as the RR-NSVT (+) group.