Impact of ICD Artifact Burden on Late Gadolinium Enhancement Cardiac MR Imaging in Patients Undergoing Ventricular Tachycardia Ablation

Background Cardiac magnetic resonance imaging (CMRI) is the gold standard for myocardial scar evaluation. Although ideal for substrate assessment in ventricular tachycardia (VT), most patients have an implantable cardioverter-defibrillator (ICD) at presentation for ablation. This study evaluates the ICD artifact burden during standard late gadolinium enhancement CMRI (LGE-CMRI) evaluation of myocardial scar in VT patients with ICDs. Methods Thirty-one patients with ICD and cardiomyopathy underwent LGE-CMRI using 1.5-T magnetic resonance scanner before VT ablation. Using the American Heart Association (AHA) 17-segment model, short-axis LGE series were analyzed for artifact burden localization and assessment. Results Preablation CMRI was performed in 31 patients with single chamber (n = 13), dual chamber (n = 11), and biventricular (n = 7) ICDs. Pre- and post-MRI ICD parameters were unchanged. All patients had susceptibility artifact and 51.6% (256 of 496) of segments were affected by artifact. The artifact area (178 ± 136 cm2) resulted in an artifact burden of 54 ± 21% of the LV myocardial area (327 ± 15 cm2). The anterior wall was most affected by artifact (89%) compared with 52%, 49%, and 23% in the lateral, septal, and inferior walls, respectively (P < 0.0001). The apical segments had more artifact burden (66%) than the mid (49%) and basal (44%) segments (P = 0.0005). Artifact area correlated with ICD-heart distance on anteroposterior chest radiograph (r = 0.42, P = 0.021) and body mass index (r = –0.48, P = 0.008). Conclusions Current clinical LGE-CMRI scar imaging protocols produce ICD artifacts that affect >50% of the LV myocardium and correlate with the ICD-heart distance. This significantly limits the application of CMRI for image-guided VT ablation.