Cardiac biomarkers in patients with permanent pacemakers and implantable cardioverter-defibrillators undergoing an MRI scan

Background: Recent series suggest that magnetic resonance imaging (MRI) scanning can be performed safely in select patients with pacemakers or implantable cardioverter-defibrillators (ICDs). Limited data have been reported on cardiac biomarker release following MRI scans in patients with pacemakers. The current study evaluated cardiac biomarkers pre- and postscan in patients with permanent pacemakers or ICDs undergoing MRI scanning of any body region without peak specific absorption rate (SAR) limit. Methods: Thirty-seven patients with a total of 75 leads underwent a total of 40 MRI scans of both truncal and nontruncal regions using usual protocols with standard peak SAR settings for the scan. No patient was pacemaker dependent. Pacemaker magnet mode and ICD therapy were disabled during the scan. Baseline cardiac troponin-I and myoglobin levels were obtained immediate pre- and 6-12 hours postscan. Pacemaker capture thresholds were measured immediately pre- and postscan. Results: The median peak SAR was 2.4 (1.3, 3.2) W/kg for all scans. Cardiac troponin-I was unchanged following an MRI scan (0.01 (0.01, 0.02) versus 0.01 (0.01, 0.02) ng/mL, P = 0.90). Capture thresholds were no different pre- and postscan (0.67 (0.50, 0.80) versus 0.70 (0.50, 0.79) V at 0.5 ms, P = 0.50). Conclusions: The current series suggests that an MRI scan may be performed safely in carefully selected patients with close monitoring during the scan without limitation on peak SAR level or body landmark. Furthermore, it is unlikely that an MRI scan will produce sufficient tissue heating to cause enough myocardial cell necrosis to result in cardiac biomarker release.