Division of Cardiology, Medical University of South Carolina, Charleston, South Carolina.
Department of Diagnostic and Interventional Radiology and Nuclear Medicine, German Red Cross Hospital, Neuwied, Germany.
J Am Coll Cardiol. 2015 Jun 23;65(24):2581-2588. doi: 10.1016/j.jacc.2015.04.047. Epub 2015 May 14.
Magnetic resonance imaging (MRI) of patients with conventional implantable cardioverter-defibrillators (ICD) is contraindicated.
This multicenter, randomized trial evaluated safety and efficacy of a novel ICD system specially designed for full-body MRI without restrictions on heart rate or pacing dependency. The primary safety objective was >90% freedom from MRI-related events composite endpoint within 30 days post-MRI. The primary efficacy endpoints were ventricular pacing capture threshold and ventricular sensing amplitude.
Subjects received either a single- or dual-chamber ICD. In a 2:1 randomization, subjects either underwent MRI at 1.5-T of the chest, cervical, and head regions to maximize radiofrequency exposure up to 2 W/kg specific absorption rate and gradient field exposure to 200 T/m/s per axis (MRI group, n = 175), or they underwent a 1-h waiting period without MRI (control group, n = 88). A subset of MRI patients underwent ventricular fibrillation induction testing post-MRI to characterize defibrillation function.
In 42 centers, 275 patients were enrolled (76% male, age 60.4 ± 13.8 years). The safety endpoint was met with 100% freedom from the composite endpoint (p < 0.0001). Both efficacy endpoints were met with minimal differences in the proportion of MRI and control patients who demonstrated a ≤0.5 V increase in ventricular pacing capture threshold (100% MRI vs. 98.8% control, noninferiority p < 0.0001) or a ≤50% decrease in R-wave amplitude (99.3% MRI vs. 98.8% control, noninferiority p = 0.0001). A total of 34 ventricular tachyarrhythmia/ventricular fibrillation episodes (20 induced; 14 spontaneous) occurred in 24 subjects post-MRI, with no observed effect on sensing, detection, or treatment.
This is the first randomized clinical study of an ICD system designed for full-body MRI at 1.5-T. These data support that the system is safe and the MRI scan does not adversely affect electrical performance or efficacy. (Confirmatory Clinical Trial of the Evera MRI System for Conditionally-Safe MRI Access; NCT02117414).
常规植入式心脏复律除颤器（ICD）患者的磁共振成像（MRI）检查是禁忌的。
这项多中心、随机试验评估了一种新型 ICD 系统的安全性和有效性，该系统专门设计用于全身 MRI 检查，不受心率或起搏依赖的限制。主要安全性目标是在 MRI 后 30 天内，MRI 相关事件复合终点的无事件发生率>90%。主要疗效终点是心室起搏夺获阈值和心室感知幅度。
受试者接受单腔或双腔 ICD 治疗。根据 2:1 的随机分组，受试者要么在胸部、颈部和头部进行 1.5-T 的 MRI，以最大限度地提高射频暴露量，达到 2 W/kg 比吸收率和梯度场暴露量，每个轴达到 200 T/m/s（MRI 组，n=175），要么在没有 MRI 的情况下等待 1 小时（对照组，n=88）。一部分 MRI 患者在 MRI 后进行心室颤动诱导测试，以评估除颤功能。
在 42 个中心，共纳入 275 名患者（76%为男性，年龄 60.4±13.8 岁）。安全性终点达到，复合终点的无事件发生率为 100%（p<0.0001）。两个疗效终点均达到，MRI 组和对照组中，起搏夺获阈值增加≤0.5 V 的患者比例差异极小（100%MRI 组 vs. 98.8%对照组，非劣效性 p<0.0001）或 R 波振幅降低≤50%的患者比例差异极小（99.3%MRI 组 vs. 98.8%对照组，非劣效性 p=0.0001）。MRI 后 24 名患者共发生 34 次室性心动过速/室颤（20 次诱导，14 次自发），感知、检测或治疗均无明显影响。
这是第一项针对 1.5-T 全身 MRI 设计的 ICD 系统的随机临床研究。这些数据支持该系统是安全的，MRI 扫描不会对电性能或疗效产生不利影响。（条件安全 MRI 访问的 Evera MRI 系统确证性临床试验；NCT02117414）。
