What is the clinical evidence from this study?

Study design: Observational. Population: Patients with a non-MRI-conditional pacemaker or ICD (n=1500). Intervention: Nonthoracic MRI at 1.5 tesla. Primary outcome: Death, generator or lead failure, induced arrhythmia, loss of capture, or electrical reset during the scanning.

February 17, 2017Open Access

Assessing the Risks Associated with MRI in Patients with a Pacemaker or Defibrillator

Key Result

Nonthoracic MRI at 1.5T in 1500 cases with non-MRI-conditional pacemakers or ICDs caused no deaths or lead failures; one ICD required replacement due to improper pre-scan programming.

Study Design

Type

Observational (n=1,500)

Structured PICO

Is nonthoracic MRI at 1.5 tesla safe in patients with non-MRI-conditional pacemakers or ICDs when using a standardized reprogramming protocol?

Population

1500 cases of patients with a 'non-MRI-conditional' pacemaker (n=1000) or implantable cardioverter-defibrillator (n=500) referred for clinically indicated nonthoracic MRI.

Intervention

Clinically indicated nonthoracic MRI at 1.5 tesla with standardized device interrogation and reprogramming before and after scanning.

Outcome

Death, generator or lead failure, induced arrhythmia, loss of capture, or electrical reset during the scanning.safety

Nonthoracic MRI at 1.5 tesla can be performed safely in patients with non-MRI-conditional pacemakers or ICDs when using a standardized screening and reprogramming protocol.

Abstract

BACKGROUND: The presence of a cardiovascular implantable electronic device has long been a contraindication for the performance of magnetic resonance imaging (MRI). We established a prospective registry to determine the risks associated with MRI at a magnetic field strength of 1.5 tesla for patients who had a pacemaker or implantable cardioverter-defibrillator (ICD) that was "non-MRI-conditional" (i.e., not approved by the Food and Drug Administration for MRI scanning). METHODS: Patients in the registry were referred for clinically indicated nonthoracic MRI at a field strength of 1.5 tesla. Devices were interrogated before and after MRI with the use of a standardized protocol and were 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. RESULTS: MRI was performed in 1000 cases in which patients had a pacemaker and in 500 cases in which patients had an ICD. 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 device had not been appropriately programmed per protocol before the MRI. We 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. CONCLUSIONS: In this 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. (Funded by St. Jude Medical and others; MagnaSafe ClinicalTrials.gov number, NCT00907361 .).