Background and Aims Patients with repaired tetralogy of Fallot remain at risk of life-threatening ventricular tachycardia related to slow-conducting anatomical isthmuses (SCAIs). Preventive ablation of SCAI identified by invasive electroanatomical mapping is increasingly performed. This study aimed to non-invasively identify SCAI using 3D late gadolinium enhancement cardiac magnetic resonance (3D-LGE-CMR). Methods Consecutive tetralogy of Fallot patients who underwent right ventricular electroanatomical mapping (RV-EAM) and 3D-LGE-CMR were included. High signal intensity threshold for abnormal myocardium was determined based on direct comparison of bipolar voltages and signal intensity by co-registration of RV-EAM with 3D-LGE-CMR. The diagnostic performance of 3D-LGE-CMR to non-invasively identify SCAI was determined, validated in a second cohort, and compared with the discriminative ability of proposed risk scores. Results The derivation cohort consisted of 48 (34 ± 16 years) and the validation cohort of 53 patients (36 ± 18 years). In the derivation cohort, 78 of 107 anatomical isthmuses (AIs) identified by EAM were normal-conducting AI, 22 were SCAI, and 7 blocked AI. High signal intensity threshold was 42% of the maximal signal intensity. The sensitivity and specificity of 3D-LGE-CMR for identifying SCAI or blocked AI were 100% and 90%, respectively. In the validation cohort, 85 of 124 AIs were normal-conducting AI, 36 were SCAI, and 3 blocked AI. The sensitivity and specificity of 3D-LGE-CMR were 95% and 91%, respectively. All risk scores showed an at best modest performance to identify SCAI (area under the curve ≤ .68). Conclusions 3D late gadolinium enhancement cardiac magnetic resonance can identify SCAI with excellent accuracy and may refine non-invasive risk stratification and patient selection for invasive EAM in tetralogy of Fallot.

中文翻译：

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三维心脏磁共振可以识别法洛四联症中的慢传导解剖峡部

背景和目的 法洛四联症修复后的患者仍然面临与慢传导解剖峡部 (SCAI) 相关的危及生命的室性心动过速的风险。通过侵入性电解剖标测识别的 SCAI 的预防性消融越来越多地进行。本研究旨在使用 3D 晚期钆增强心脏磁共振 (3D-LGE-CMR) 无创性识别 SCAI。方法 纳入连续接受右心室电解剖标测（RV-EAM）和 3D-LGE-CMR 的法乐氏四联症患者。通过 RV-EAM 与 3D-LGE-CMR 的共同配准，直接比较双极电压和信号强度，确定异常心肌的高信号强度阈值。确定了 3D-LGE-CMR 无创识别 SCAI 的诊断性能，并在第二个队列中进行了验证，并与建议的风险评分的辨别能力进行了比较。结果 推导队列由 48 名患者（34 ± 16 岁）组成，验证队列由 53 名患者（36 ± 18 岁）组成。在推导队列中，EAM 识别的 107 个解剖峡部 (AI) 中，78 个为正常传导 AI，22 个为 SCAI，7 个为阻塞 AI。高信号强度阈值为最大信号强度的 42%。 3D-LGE-CMR 识别 SCAI 或阻断 AI 的敏感性和特异性分别为 100% 和 90%。在验证队列中，124 个 AI 中有 85 个为正常传导 AI，36 个为 SCAI，3 个为阻断 AI。 3D-LGE-CMR 的敏感性和特异性分别为 95% 和 91%。所有风险评分最多都显示出识别 SCAI 的适度性能（曲线下面积 ≤ 0.68）。结论 3D 晚期钆增强心脏磁共振可以非常准确地识别 SCAI，并可以完善法洛四联症侵入性 EAM 的无创风险分层和患者选择。