Mesubi Olurotimi, Ahmad Ghada, Jeudy Jean, Jimenez Alejandro, Kuk Richard, Saliaris Anastasios, See Vincent, Shorofsky Stephen, Dickfeld Timm
Maryland Arrhythmia and Cardiology Imaging Group (MACIG), University of Maryland, Baltimore, Maryland; Division of Cardiology, University of Maryland, Baltimore, Maryland; Division of Cardiovascular Medicine, University of Iowa, Iowa City, Iowa.
Pacing Clin Electrophysiol. 2014 Oct;37(10):1274-83. doi: 10.1111/pace.12405. Epub 2014 Apr 26.
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.
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.
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 cm(2) ) resulted in an artifact burden of 54 ± 21% of the LV myocardial area (327 ± 15 cm(2) ). 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).
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.
心脏磁共振成像（CMRI）是评估心肌瘢痕的金标准。虽然CMRI非常适合用于室性心动过速（VT）的基质评估，但大多数患者在进行消融治疗时已植入植入式心脏复律除颤器（ICD）。本研究评估了在对植入ICD的VT患者进行标准延迟钆增强CMRI（LGE-CMRI）心肌瘢痕评估期间的ICD伪影负担。
31例植入ICD且患有心肌病的患者在VT消融术前使用1.5-T磁共振扫描仪进行了LGE-CMRI检查。采用美国心脏协会（AHA）17节段模型，对短轴LGE序列进行伪影负担定位和评估。
31例患者进行了消融术前CMRI检查，其中单腔ICD患者13例，双腔ICD患者11例，双心室ICD患者7例。MRI检查前后ICD参数未发生变化。所有患者均有磁化率伪影，496个节段中有51.6%（256个）受到伪影影响。伪影面积（178±136 cm²）导致伪影负担占左心室心肌面积（327±15 cm²）的54±21%。前壁受伪影影响最大（89%），而侧壁、间隔壁和下壁分别为52%、49%和23%（P<0.0001）。心尖节段的伪影负担（66%）高于中间节段（49%）和基底节段（44%）（P = 0.0005）。伪影面积与前后位胸部X线片上的ICD与心脏距离相关（r = 0.42，P = 0.021），与体重指数相关（r = -0.48，P = 0.008）。
目前临床LGE-CMRI瘢痕成像方案产生的ICD伪影影响超过50%的左心室心肌，且与ICD与心脏距离相关。这显著限制了CMRI在图像引导VT消融中的应用。
