Most exposures to electromagnetic interference are transient and pose no threat to patients with pacemakers and implantable cardioverter defibrillators. Prolonged exposure may be catastrophic in pacemaker dependent patients. New technologies (wireless phones, electronic antitheft surveillance) are safe if proper precautions are takes. Radiofrequency ablation requires concomitant temporary pacing. MR imaging remains contraindicated in patients with these devices until further study is undertaken.