Facts about pacemakers

•About 1 million people a year worldwide are implanted with a pacemaker.

•An estimated 1.5 million Americans have a pacemaker today.

•Medtronic Inc., St. Jude Medical Inc. and Boston Scientific Corp. are the main companies making pacemakers.

•After age 65, a person's chance of needing medical imaging doubles -- the same demographic group that is most likely to need an electronic implantable device.

•A patient with an electronic implantable device has a 50 percent to 75 percent likelihood of need an MRI over the lifetime of their device, but is advised against getting one.

•Approximately 60 million MRI procedures are performed worldwide each year.