What a New Study Reveals About MRI Use and Implantable Cardioverter Defibrillators

Emerging research suggests that 1.5-Tesla magnetic resonance imaging (MRI) has no serious adverse impact on the capability of implantable cardioverter defibrillators (ICDs) to detect and treat arrhythmias.

In the prospective cohort study, recently published in Annals of Internal Medicine, researchers reviewed clinical data for 629 patients (median age of 62.7) with ICDs and a total of 813 1.5-Tesla MRI exams. In addition to baseline ICD interrogations and interrogations performed after MRI, the study authors also reviewed data from symptom-prompted interrogations and recommended interrogations performed at least every six months, according to the study.

During a median follow-up period of 2.2 years, the researchers said there was a total of 4,177 detected arrhythmias in 237 patients. With the exception of three deaths, the researchers found the use of ICDs successfully treated and terminated all spontaneous arrhythmias. Out of the 210 deaths reported in the study cohort, 10 patients had arrhythmia-related cardiac deaths. The researchers noted that shocks were not indicated in seven patients who had pulseless electrical activity and two patients had ventricular tachycardia or ventricular fibrillation that was refractory to appropriate shocks.

The researchers added there were no syncope episodes attributed to abnormalities in ICD detection of arrhythmias. The study authors also noted no detection delays from undersensing in episodes of ventricular tachycardia or ventricular fibrillation.

“Our findings are consistent with the accumulating evidence that 1.5-Tesla MRI scans do not induce clinically significant functional changes in non-MRI conditional ICDs, which could theoretically be due to heating at the lead-tissue interface, lead or generator dislodgement, or hardware and software damage after MRI,” wrote study co-author Henry R. Halperin, M.D., a professor of medicine, radiology, and biomedical engineering at Johns Hopkins University.

(Editor’s note: For related content, see “Can Emerging AI-Guided Software Rein in Scan Times for Cardiac MRI?” and “Could Photon Counting Reduce Iodinated Contrast Media for CT Angiography?”)

Despite widespread use of non-MRI conditional ICD systems, the study authors maintained that misperceptions about MRI safety contribute to health-care inequities in this patient population.

“ … A substantial patient population with non-MRI-conditional ICDs currently exists with continued inequities in access to clinically indicated MRI examinations, likely from continued perceived risks of MRI examinations in patients with these devices,” emphasized Halperin and colleagues. “Our study provides additional safety data for this patient population under a standardized imaging protocol.”

In regard to study limitations, the authors acknowledged the inherent limitations of a single center study that may preclude extrapolation of the findings to other clinical settings and MRI facilities. Halperin and colleagues pointed out that 15 percent of patients in the study did not have follow-up ICD interrogations and there was no mortality data for 30 of these patients who were lost to follow-up. According to the study, 12 percent of patients died within a year of having MRI and 21 percent died within three years of having MRI. While the researchers suggested these patients may have reflected a “sicker” population who had non-cardiac-related indications for MRI, they conceded the lack of a comparison group with MRI-conditional ICDs and similar indications for MRI.