Evera MRI | Clinical Trial - Evera MRI
The goal of this trial was to assess the safety and efficacy of a magnetic resonance imaging (MRI)-safe implantable cardioverter-defibrillator (ICD) system designed for full body imaging.
Contribution to the Literature: Evera MRI is the first trial to show safety and efficacy of a novel MRI-safe ICD system in clinical patient populations.
Patients receiving an Evera-ICD were randomized in a 2:1 fashion to either MRI or to undergo a 1-hour waiting period without MRI (control) 9-12 weeks after implant.
- Implantation of single- or dual-chamber ICD
- Pectoral implant
- MRI testing with 1.5T machine
- Total number of enrollees: 263
- Duration of follow-up: 4.5 months
- Mean patient age: 60.4 years
- Percentage female: 24%
- Percentage with ICD indication: Primary prevention (74%), secondary prevention (26%)
- Percentage with atrial fibrillation: 25%
Primary safety endpoint: 100% complication-free rate was met, with no sustained ventricular tachycardia (VT) episodes during MRI, and no MRI-related complications or lack of capture (p < 0.0001). Five MRI-related observations were reported (one episode of atrial tachycardia during the scan associated with asynchronous pacing). Mortality for the MRI group vs. control was 4.6% vs. 4.5%.
Primary efficacy endpoint: Change in ventricular pacing capture threshold: 0.0 vs. 0.02 V. Mean change in R-wave amplitude was -0.1 vs. 0.04 mV. Fourteen spontaneous VT/ventricular fibrillation (VF) episodes were observed during follow-up, with no significant detection delay. Among 120 patients with a dual-chamber ICD, ≤0.5 V increase in atrial pacing at 0.4 msec was 98.7% vs. 100% (p = 0.006).
This is the first randomized controlled trial of fully body imaging of an MRI-safe ICD. The trial found no adverse effects with a standardized, 1.5T MRI protocol. Pacing and sensing were not significantly impacted by MRI, with normal arrhythmia detection and defibrillation function documented following these exams. This is an important advance since patients with ICDs have traditionally been excluded from receiving MRIs. Reasons include the induction of ventricular arrhythmias during the MRI procedure, adverse changes in pacing or sensing as a consequence of MRI, and abnormal defibrillation function due to the exposure.
Larger registries to document continued safety and efficacy of this ICD system will be important, if this device receives Food and Drug Administration (FDA) approval. It is also unclear if more powerful MRI systems, such as 3T, or scans performed either immediately after ICD implant or in those with long-standing devices (all patients in this trial had de novo implants), will demonstrate similar safety and efficacy.
Gold MR, Sommer T, Schwitter J, et al., on behalf of the Evera MRI Study Investigators. Full-Body MRI Scanning in Patients With an ICD: Primary Results of the Randomized Evera MRI Study. J Am Coll Cardiol 2015;May 14:[Epub ahead of print].
Editorial Comment: Moss AJ, Kutyifa V. Safe MRI Scanning in Patients Implanted With an Upgraded (Conditional) ICD: The Beneficial Tip of a Troublesome Iceberg. J Am Coll Cardiol 2015;May 14:[Epub ahead of print].
Clinical Topics: Arrhythmias and Clinical EP, Noninvasive Imaging, Prevention, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Magnetic Resonance Imaging
Keywords: Arrhythmias, Cardiac, Atrial Fibrillation, Defibrillators, Implantable, Diagnostic Imaging, Electric Countershock, Heart Conduction System, Magnetic Resonance Imaging, Pacemaker, Artificial, Primary Prevention, Secondary Prevention, Tachycardia, Ventricular, Ventricular Fibrillation
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