This article is more than 5 years old. Information may no longer be current.
ProMRI: ICD safe in patients undergoing cardiac, thoracic spine MRI
BOSTON — An implantable cardioverter defibrillator was safe and effective in patients undergoing a cardiac or thoracic spine MRI at 1.5 T, according to the results of the ProMRI study.
Researchers conducted a multicenter prospective, single-arm, nonrandomized study to evaluate the clinical safety of the ICD system (Iforia ProMRI, Biotronik). Khaled Awad, MD, from the University of Alabama at Birmingham, and colleagues enrolled 170 patients implanted with a dual-chamber (DR-T) or single-chamber (VR-T DX) ICD system. Nondiagnostic cardiac MRI or thoracic spine MRI was performed at least 1 week after enrollment, with the ICDs placed into MRI mode, with ventricular fibrillation detection and therapy programmed off.
Khaled Awad
Researchers monitored cardiac rhythm during the scan and interrogated the device before, immediately after and 1 month following the MRI.
The primary endpoints were freedom from serious adverse device events, freedom from ventricular capture threshold increase > 0.5 V at 1 month and freedom from decrease in R-wave sensing (defined as decrease in R-wave sensing > 50% at 1 month or R-waves < 5 mV at 1 month).
Of the 170 patients enrolled, 154 (mean age, 60 years; 77% men; 22% with ICD indication for secondary prevention) were programmed to MRI mode and 150 had 1-month follow-up.
There were no adverse events related to the ICD system and device, meaning the rate of freedom from serious adverse device events was 100% (P < .001), Awad said during a press conference. Of the 43 events reported to investigators, most were not serious, he said.
Freedom from ventricular capture threshold increase > 0.5 V at 1 month was 100% (P < .001).
Freedom from decrease in R-wave sensing was 99.3% (P < .001). The one patient who did not meet the endpoint did not undergo an MRI because of claustrophobia.
Post-MRI, 403 episodes of ventricular arrhythmia were detected in 39 patients; all episodes were properly detected and treated, he said.
“Most important, there was no impact on the ICD’s main function, which is detecting and treating ventricular arrhythmias,” he said. “We think these data demonstrate the safety and efficacy of that ICD system as configured under those specific MRI conditions.”
The device received FDA approval in 2014, but it has not yet been approved for use with MRI, Awad said. “I think regulatory changes are needed in the future to allow for routine scanning of patients with ICDs that are specifically designed for the MRI environment,” he said. – by Erik Swain
Reference:
Awad K, et al. Abstract LBCT02-04. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 13-16, 2015; Boston.
Disclosure: The study was funded by Biotronik. Awad reports no relevant financial disclosures.
Perspective
Back to Top
This study looked at the safety of performing MRI scans in patients with ICDs. Many patients will require an MRI scan some time during their lifetime. However, they will not be able to have this potentially very important diagnostic study performed if they have an ICD. In the United States, there is no ICD that is currently approved by the FDA for MRI scanning. This trial, sponsored by Biotronik, demonstrated that we can actually safely perform MRIs in these patients, without damage to the lead or device, and no significant adverse effects were seen. At 1 month, there was good stability in the pacing and sensing parameters, and the devices functioned normally. These findings are very exciting. We now need longer-term data to see if there are any other effects on the system that we are not aware of right now.