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In the past, MRIs have been considered dangerous for people with implanted defibrillators and pacemakers.

However, new research has found that magnetic resonance imaging is safe for cardiac electronic devices, even for chest imaging, for both conditional and non-conditional devices.

Led by researchers from the in the US, 鈥楻eal World MRI Experience with Non-Conditional and Conditional Cardiac Rhythm Devices After MagnaSafe鈥�, published in the , found that MRI imaging can be safely performed on patients with devices.

鈥淢agnetic resonance imaging has become very popular,鈥� said Dr Jeffrey Anderson, senior study author and cardiologist at the Intermountain Medical Center Heart Institute. 鈥淚t鈥檚 excellent for looking at soft tissue changes. But it involves very high-strength magnetic fields, which means if a patient has any implanted metal devices containing iron, it could potentially cause harm.鈥�

X-rays can see bone, but they don鈥檛 provide much information about soft tissues like the brain, the heart or other internal organs. 鈥淢RIs are marvelous for that,鈥� Dr聽Anderson said.

The researchers evaluated 212 MRI studies in 178 patients with a cardiac implantable electronic device between February 2014 and August 2016. They didn鈥檛 find a single problem requiring remediation in the entire series, which involved a total of 418 implanted leads.

鈥淭hat鈥檚 a pretty big number of leads exposed to these very strong MRI fields. You would think if there was even a 1% chance of having a problem, it would have shown up,鈥� Dr聽Anderson said. 鈥淣ot even one generator or lead needed more than a minor adjustment, if any at all.鈥�

In the past, MRIs have been considered risky because of the fear a pacemaker or defibrillator device鈥檚 generator circuits could be disrupted; its metal leads could be pulled out of place by the magnetism; or the lead tips could become hot and scar surrounding tissues, interfering with pacing and defibrillating function.

To counter that, some newer devices have been specifically made and tested to be safe for use with MRIs under certain test conditions in magnetic fields. Devices in this category are referred to as 鈥榗onditional CIEDs鈥� (cardiac implantable electronic devices) and have been approved for MRI use under imaging conditions implemented by the US聽Food and Drug Administration.

Most people who have implantable defibrillators and pacemakers don鈥檛 have these newer, more expensive conditional devices, however. Rather, they have standard non-conditional devices. In patients with non-conditional devices who have a medical need for imaging, and in whom MRI is deemed the most desirable diagnostic tool, MRI usually hasn鈥檛 been used, or the non-conditional devices and leads have been removed and replaced with conditional devices and leads beforehand.

Imaging decision-making for those with cardiac implantable electronic devices has started to change with publication this year of a large multicentre study called the MagnaSafe Registry study, which showed that non-conditional devices can be safely imaged by MRI if proper precautions are observed. Published in the , the study was limited in that it looked at the safety of MRIs only in parts of the body not in direct proximity to the implantable cardiac rhythm devices, which are typically in the chest under one of the collarbones.

The new Intermountain Medical Center Heart Institute study directly builds on the MagnaSafe study, validating findings of the main MagnaSafe cohort of 1500 patients and expanding that group of patients to include those who need an MRI of their lungs, heart or other organs within the chest.

In addition, the new study includes many patients with conditional devices, providing a side-by-side comparison of the two types of devices.

Dr聽Anderson said the research confirms the MagnaSafe findings and shows it is also safe to use MRI to look at the heart or lungs in patients with these implantable devices.

Image credit: 漏stock.adobe.com/au/merly69