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Pacemaker system designed for use during MRI demonstrates safety in worldwide trial
No MRI-related complications occurred in patients implanted with the new pacemaker system.
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Heart Rhythm Society's 30th Annual Scientific Sessions
The EnRhythm pacemaker system was found safe and effective in patients undergoing magnetic resonance imaging, according to trial results presented this morning at Heart Rhythm 2009.
The pacemaker system (EnRhythm, Medtronic), designed to minimize lead tip heating and provide a programmable MRI pacing mode, was implanted in 464 patients who were then randomly assigned to either receive or not receive an MRI; 244 MRI scan visits occurred. Researchers followed 444 patients of the total study population for one month following the scans. The primary safety endpoint was freedom from procedure-related complications, and the efficacy was measured using capture thresholds and sensing amplitudes.
According to the study results, no MRI procedure-related complications or MRI-attributed sustained ventricular arrhythmias, asystole episodes or pacemaker malfunctions occurred. According to the study abstract, the system-related complication-free rate was 91.7% (P<.001). Atrial pacing capture thresholds were similar between the MRI group and control group (–0.01 ± 0.23 vs. –0.04 ± 0.64), as were ventricular pacing thresholds (0 ± 0.21 vs. 0.04 ± 0.39). Sensing amplitude decreases of >50% occurred for atrial leads in 5.3% of the MRI group vs. 7.2% of the control group, and for ventricular leads in 3% of the MRI group compared with 5.1% of the control patients. No arrhythmias were identified.
The pacemaker system is available in Europe but is not FDA approved.
“There were no complications attributed to the MRI scan, no evidence of clinical bradycardia or tachycardia, nor was there subclinical pacemaker performance or technical pacemaker or lead damage in the patients receiving MRI scans,” Bruce L. Wilkoff, MD, director of cardiac pacing and tachyarrhythmia devices at the Cleveland Clinic, said in his presentation. “In the MRI environment under specific guidelines, the new pacemaker system facilitates access to this important diagnostic imaging technique.”– by Eric Raible
For more information:
- Wilkoff B. LBCT I. Presented at: Heart Rhythm 2009; May 13-16; Boston.
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