MRIs May Be Safe Even For Patients with “Non-MRI-Conditional” Pacemakers or ICDs

March 10, 2017

Magnetic resonance imaging may be possible for patients even if they have pacemakers or ICDs that have not been approved by the FDA for MRI scanning.

Non–MRI-conditional pacemaker or ICD may not be a contraindication for MRI, according to a study published in The New England Journal of Medicine.

Researchers from several states sought to determine the risks associated with MRI at a magnetic field strength of 1.5 tesla for patients who had a pacemaker or ICD that was not approved by the Food and Drug Administration for MRI scanning, thereby considered to be non–MRI-conditional.

One thousand patients with a pacemaker and 500 with an ICD were included in the study. The patients had been referred for clinically indicated nonthoracic MRI at a field strength of 1.5 tesla. The researchers interrogated the devices before and after MRI with the use of a standardized protocol and were the devices appropriately reprogrammed before the scanning. The primary end points were death, generator or lead failure, induced arrhythmia, loss of capture, or electrical reset during the scanning. The secondary end points were changes in device settings.

The results showed that no deaths, lead failures, losses of capture, or ventricular arrhythmias occurred during MRI. One ICD generator could not be interrogated after MRI and required immediate replacement. The researchers noted that the device had not been appropriately programmed per protocol before the MRI. The researchers also observed six cases of self-terminating atrial fibrillation or flutter and six cases of partial electrical reset. Changes in lead impedance, pacing threshold, battery voltage, and P-wave and R-wave amplitude exceeded prespecified thresholds in a small number of cases. Repeat MRI was not associated with an increase in adverse events.

The researchers concluded that in their study, “device or lead failure did not occur in any patient with a non–MRI-conditional pacemaker or ICD who underwent clinically indicated nonthoracic MRI at 1.5 tesla, was appropriately screened, and had the device reprogrammed in accordance with the prespecified protocol.”