Implantable Defibrillator System Shock Function, Mortality, and Cause of Death After Magnetic Resonance Imaging.

BACKGROUND

Studies have shown that magnetic resonance imaging (MRI) does not have clinically important effects on the device parameters of non-MRI-conditional implantable cardioverter-defibrillators (ICDs). However, data on non-MRI-conditional ICD detection and treatment of arrhythmias after MRI are limited.

OBJECTIVE

To examine if non-MRI-conditional ICDs have preserved shock function of arrhythmias after MRI.

DESIGN

Prospective cohort study. (ClinicalTrials.gov: NCT01130896).

SETTING

1 center in the United States.

PATIENTS: 629 patients with non-MRI-conditional ICDs enrolled consecutively between February 2003 and January 2015.

INTERVENTIONS: 813 total MRI examinations at a magnetic field strength of 1.5 Tesla using a prespecified safety protocol.

MEASUREMENTS: Implantable cardioverter-defibrillator interrogations were collected after MRI. Clinical outcomes included arrhythmia detection and treatment, generator or lead exchanges, adverse events, and death.

RESULTS

During a median follow-up of 2.2 years from MRI to latest available ICD interrogation before generator or lead exchange in 536 patients, 4177 arrhythmia episodes were detected, and 97 patients received ICD shocks. Sixty-one patients (10% of total) had 130 spontaneous ventricular tachycardia or fibrillation events terminated by ICD shocks. A total of 210 patients (33% of total) are known to have died (median, 1.7 years from MRI to death); 3 had cardiac arrhythmia deaths where shocks were indicated without direct evidence of device dysfunction.

LIMITATIONS: Data were acquired at a single center and may not be generalizable to other clinical settings and MRI facilities. Implantable cardioverter-defibrillator interrogations were not available for a subset of patients; adjudication of cause of death relied solely on death certificate data in a subset.

CONCLUSION

Non-MRI-conditional ICDs appropriately treated detected tachyarrhythmias after MRI. No serious adverse effects on device function were reported after MRI.

PRIMARY FUNDING SOURCE: Johns Hopkins University and National Institutes of Health.