Cardiac Magnetic Resonance as Risk Stratification Tool in Non-Ischemic Dilated Cardiomyopathy Referred for Implantable Cardioverter Defibrillator Therapy—State of Art and Perspectives

Figure 1. (A,B) show short axis views of the basal and mid segments in late gadolinium enhancement (LGE) sequences in a patient with non-ischemic cardiomyopathy and LVEF 40%. Extensive LGE (mid-wall septal and subepicardial) is observed. This patient had sustained monomorphic VT and underwent successful epicardial VT ablation. (C,D) show short axis views of the basal and mid segments in LGE sequences in a patient with non-ischemic cardiomyopathy and LVEF 27%. No LGE is observed. This patient has never experienced ventricular arrhythmias during follow-up.

Figure 2. Functional correlation between the scar identified with late gadolinium enhancement and the ventricular tachycardia circuit in a patient with non-ischemic cardiomyopathy. In (A), CMR images are reconstructed with the ADAS 3D software (ADAS 3D Medical, Barcelona, Spain, https://www.adas3d.com) to identify border zone corridors. In this case one corridor is identified in the subepicardium of the mid-lateral left ventricular wall. This corridor nicely matches with the critical isthmus of the sustained monomorphic tachycardia induced during the ablation procedure, shown in (B). Ablation inside the isthmus determined the interruption of the ventricular tachycardia after 6 s (B).

Figure 3. Schematic representation of a potential risk-stratification and ICD selection strategy based on LGE. Additional factors may have variable prognostic weight in different sub-population of LGE + DCM patients. Risk factors for non-sudden death, such as Age, NYHA class and comorbidities will also influence ICD benefit. LGE: late gadolinium enhancement. VA: ventricular arrhythmias. SD: sudden death. ICD: Implantable cardioverter defibrillator. LVEF: left ventricular ejection fraction. ECV: extracellular volume fraction. NSVT: non sustained ventricular tachycardia. * LGE− patients with very severe LV dysfunction (LVEF ≤ 20%) have been suggested to have higher risk of VA/SD; however, these patients might have a not negligible competing risk of non-sudden death with a direct impact on the potential benefit of primary prevention ICD.