Is MR safe with ICD and pacemaker patients?

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While no definitive answer presents itself to this question, Edward Martin, MD, an invasive/noninvasive cardiologist at the Oklahoma Heart Institute in Tulsa, Okla., said that the presence of an implantable cardioverter-defibrillator (ICD) is more complex than the presence of a pacemaker when imaging a patient. Martin presented his lecture in a series “The Latest Advances in Cardiovascular MRI” at the Transcatheter Cardiovascular Therapeutics meeting this week in Washington, D.C.

Martin said that 2.4 million U.S. patients have pacemakers, and 400,000 patients have an ICD. There are 15,000 MRI systems implemented worldwide, and 80 million studies are being conducted each year.

The current concerns about doing an MR on a patient with an ICD or pacemaker are: asynchronous pacing can be pro-arrythmic; experimental myocardial infarction can produce a lack of output, with resolution of continuous monitoring; and induced-currents may cause heating of lead-tissue may interface with a threshold check required post-scan.

Currently, the ICD needs to be shut off, or use sub-threshold and asynchronous programming during an MRI exam.

According to Martin, 17 deaths have occurred in patients with pacemakers who have gone through an MRI. Unfortunately, those deaths were unmonitored, therefore, there is no information on the deaths, Martin said.

Martin reviewed a prospective institutional review board-approved study of 61 MRI exams in 54 patients, most of whom were non-pacemaker dependent. The results showed no changes in battery volume, including the two patients with pacemakers. Out of 308 leads, 145 right atrial and 162 left ventricular and one in coronary sinus, there were 11 significant changes. The two patients with pacemakers required increased programming, and one patient died, but it was not related to the pacemaker.

Martin strongly recommends that patients who are pacemaker-dependent put the devices in the asynchronous mode when undergoing an MRI. He noted additional complications of an increased force and torque and a saturation of the transformer.