Abstract 21511: Cardiac MR in Patients with Implanted Defibrillators: Safety and Image Quality
Objectives: The presence of a defibrillator (ICD) has been considered a contraindication to MRI, however small series of patients have been reported. Cardiac MR (CMR) in ICD patients is challenging given artifacts caused by generator and leads. We evaluated safety and factors contributing to image quality in ICD patients undergoing CMR
Methods: Retrospective analysis of 43 patients from 07/08 to 05/10. Informed consent was obtained and CMR was performed at 1.5T. The ICD was interrogated prior to the study and tachycardia detection and therapy disabled; pacemakers were programmed to VVI mode at 40 bpm in non-dependent patients or higher if ectopy was less pronounced at that rate. CMR sequences were adapted to minimize energy deposition (SAR) and image artifact. After CMR, ICDs were re-interrogated and returned to previous settings.
Results: One study was performed for congenital heart disease, the remainder for scar evaluation prior to EP ablation. Devices from all three major manufacturers, including single chamber, dual chamber, and biventricular leads were scanned. Generators had been implanted an average of 35 ± 28 months (range 0–120), leads for 44 ± 37 months (range 0–120). All studies were completed safely: no patients reported discomfort. There were 2 episodes of nonsustained VT, neither required treatment. All devices could be interrogated after CMR. There were no clinically relevant changes in parameters, including pacing and sensing thresholds, lead impedances, and battery voltages. Spin echo sequences were less affected by generator artifact than gradient echo; SSFP cine images were not interpretable, while non-balanced gradient echo cine images had variable quality. Delayed enhancement images were severely limited in 3/42 cases (1study was noncontrast). Factors associated with increased study quality included: study performed for evaluation of ARVC/D (8/43) and right sided generator placement (1/43). Factors associated with decreased quality included: ectopy requiring real-time SSFP cine (2/43) and smaller distance from generator to heart.
Conclusions: CMR was performed safely in 43 ICD patients, with diagnostic image quality in almost all cases. A variety of patient specific factors contribute to image quality in these studies.
- © 2010 by American Heart Association, Inc.