Full-Body MRI in Patients With an Implantable Cardioverter-Defibrillator: Primary Results of a Randomized Study

• Published in: Journal of the American College of Cardiology 2015-06, Vol.65 (24), p.2581-2588
• Main Authors: Gold, Michael R, Sommer, Torsten, Schwitter, Juerg, Al Fagih, Ahmed, Albert, Timothy, Merkely, Béla, Peterson, Michael, Ciuffo, Allen, Lee, Sung, Landborg, Lynn, Cerkvenik, Jeffrey, Kanal, Emanuel
• Format: Article
• Language: English
• Subjects: Aged; Cardiovascular Diseases - diagnosis; Cardiovascular Diseases - epidemiology; Cardiovascular Diseases - therapy; Defibrillators, Implantable - adverse effects; Electric Countershock - adverse effects; Electric Countershock - instrumentation; Electric Countershock - methods; Female; Follow-Up Studies; Humans; Internationality; Magnetic Resonance Imaging - adverse effects; Magnetic Resonance Imaging - methods; Male; Middle Aged
• ISSN: 0735-1097; 1558-3597
• DOI: 10.1016/j.jacc.2015.04.047

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).