MRI is often required for patients with cardiac implanted electronic devices (CIED). MRI has been reported to be safe in these patients when appropriate device programming changes are performed prior to the scan. Nevertheless, prior protocols excluded patients with abandoned leads or pacemaker-dependency.^1,2 The goal of this study is to examine whether this protocol is applicable to a consecutive group of patients including patient groups who were excluded in prior reports.

The protocol followed at our institution for MR imaging of CIED patients is limited to 1.5T scanners, where the scan ordering is based on necessity and absence of an alternative imaging modality. The device-related relative contraindications include the presence of abandoned leads, pacemaker dependency, and time to lead implant <6 weeks, with the possibility of the ordering physician overruling these exclusions. The protocol and pre-MRI assessment include interrogation of baseline device characteristics: threshold testing, sensing, battery voltage and impedance as well as pacing dependency. A provider with CIED management expertise assesses the baseline device information, where the device is programmed according to the patients’ needs with tachyarrhythmia detection and therapy disabled during the scan. The patients’ rhythm and vital signs are monitored while the patient is in the scanner. Device reinterrogation and reprogramming are performed after completion of the scan, as well as at 1-week and 3-months after imaging.

The cardiac scans were performed to assess the existence of late-gadolinium enhancement (LGE) prior to ventricular tachycardia (VT) ablation procedures. The imaging protocol consists of cine short-axis and long-axis images (SSFP sequence, TR = 4.2 ms, TE = 1.8 ms, resolution = 1.4×1.4 mm², slice thickness = 8 mm) as well as 2D LGE imaging (inversion recovery sequence, TR = 6.7 ms, TE = 3.2 ms, resolution = 1.4×2.2 mm², slice thickness = 8 mm, specific absorption rate (SAR) limit = 2 W/Kg). The brain imaging protocol included axial T2-weighted, T1-weighhted, and FLAIR images, as well as axial and coronal post-contrast T1-weighted images (slice thickness/gap = 5/1 mm, total scan time ~16 minutes). The spine imaging protocol included sagittal and axial T2-weighted fast spin-echo, T1-weighted spin-echo, and post-contrast T1-weighted spin-echo images (sagittal and axial slice thickness/gap = 4/0.4 mm and 5/2 mm, respectively, total scan time ~15 minutes).

A total of 162 MRI scans were obtained in 142 consecutive patients with CIED’s (106 patients had defibrillators and 36 patients had pacemakers, as shown in Table 1). Twenty-nine patients were pacemaker-dependent and 11 patients had abandoned leads. Cardiac MRI scans were performed in 94 patients and spinal/brain scans were performed in 47 patients. In one patient, 2 cardiac scans were performed. In the cardiac scans, the images were non-diagnostic only in 4 patients due to extensive artifacts from the implanted cardiac defibrillator (ICD). In 65 patients, LGE was detected without artifacts. No LGE was identified in 25 scans. In the brain/spine scans, eight patients underwent multiple studies and one patient underwent 7 scans. All, except one, brain/spinal scans were diagnostic without artifacts. Only one patient developed VT during a spine scan and was removed from the scanner for device reactivation, which terminated VT without consequences. No other adverse events were noted. The device parameters essentially remained the same immediately, 1-week, and 3-months after the scans, as shown in Table 2. No changes in the device parameters occurred that required reprogramming of any device. Some significant differences in the lead impedances were detected when the baseline impedances were compared to the impedance 1-week after the scan in the atrial leads, defibrillation lead, and coronary sinus pacing leads. Nevertheless, these changes could not be detected at 3-months after the scan.The present study demonstrates that cardiac and non-cardiac MRI could be safely performed in patients with abandoned pacemaker and defibrillator leads as well as in pacemaker-dependent patients. No major adverse events occurred in these patients. In the analyzed cohort of 142 patients, only in one pacemaker-dependent patient, the heart rate dropped from 90 to 50 bpm during spinal imaging using a fast spin-echo sequence (SAR = 1.89W/Kg) due to elevated noise rate of the ICD. In this patient, a prior cardiac scan was performed a week earlier where no problems were observed, as the cardiac LGE sequence has low SAR of 0.11W/Kg. Therefore, with the protocol described in this study, MR imaging could be safely performed in CIED patients without exposing the patients to risk, despite pacemaker dependency, presence of abandoned leads, and other CIED contraindications. This study recommends that MR imaging be available to more CIED patients who can benefit from it.