Food and Drug Administration Perspective

In April 2005, the US Food and Drug Administration (FDA) commented on the current research regarding the use of magnetic resonance imaging (MRI) on patients with a pacemaker or implantable cardioverter-defibrillator (ICD).1 Pacemaker and ICD labeling currently cautions physicians against the use of MRI, and MRI manufacturers contraindicate MRI for pacemaker and ICD patients. As discussed in our previous editorial, several studies have demonstrated the potential for MRI to be performed in pacemaker or ICD patients without serious clinical consequence.2–4 Studies presented by Sommer et al5 and Nazarian et al6 in this issue of Circulation offer further promising evidence in this regard. As with the previous studies, however, the authors acknowledge a multitude of limitations that prevent broad applicability of the results. Furthermore, one of these studies was not entirely free from concerning outcomes with the potential for serious clinical events. We view these results as consistent with our previous message that, on a case-by-case basis, the diagnostic benefit from MRI outweighs the presumed risks for some pacemaker and ICD patients. However, the FDA remains firm in its belief that those risks have not yet been characterized and mitigated sufficiently to justify the routine use of MRI in those populations. The FDA continues to believe that a more thorough evaluation of concerns related to heating, arrhythmogenesis, and proper device function during and after MRI, as well as validated MR protocols, should be available before approval for labeling that …