Objective: To investigate the impact of myocardial scar and drug treatment response on the risk of ventricular arrhythmia in patients with nonischemic cardiomyopathy(NICM). Methods: A retrospective analysis was conducted on 77 NICM patients with left ventricular ejection fraction (LVEF)≤35% who underwent cardiac magnetic resonance (CMR) with late gadolinium enhancement (LGE) and received drug treatment. The LVEF change during the one-year follow-up period were collected. Response to drug treatment was defined as LVEF increase≥10% within one year. The primary outcome endpoint is ventricular tachyarrhythmia (VTA), which includes persistent ventricular tachycardia (VT), ventricular fibrillation (VF), sudden cardiac death (SCD), and aborted SCD. The secondary endpoint is the long-term composite endpoint of VTA, all-cause mortality, and heart failure hospitalization (HFH).Kaplan Meier curves and Log rank tests were used for survival analysis, while Cox proportional hazards regression was used for multivariate analysis.Results: After a median of 34(16-49) months follow-up,The change in LVEF within one year after drug treatment were not related to LGE (P=0.379), but negatively correlated with LGE burden, with a correlation coefficient of -0.295 (95% CI: -0.487~-0.076, P=0.009).During follow up,five patients experienced VTA events. In survival analysis,VTA events were associated with LGE burden (P=0.005) and not with the presence of LGE and drug response (P=0.309,P=0.890). In the multivariate Cox regression model, LGE burden was an independent risk factor of VTA events (HR=1.075, 95% CI 1.002-1.054, P=0.043). The long-term composite endpoint of NICM patients is related to LGE burden and changes in LVEF (P=0.040, P=0.025).Conclusion: LGE burden is an independent risk factor of VTA events in NICM patients, and the occurrence of VTA events is not related to drug treatment response.