Why might I not be able to have an MRI scan?

An x-ray image showing someone with a pacemaker

I have a pacemaker and have been told I can’t have an MRI scan, why is this?

Dr Mike Knapton says:

An MRI scanner uses very strong magnetic fields to create a detailed image of the inside of your body. These magnets may affect any metal implants or fragments in your body – including pacemakers and their wires but also implantable cardioverter defibrillators (ICDs), metal heart valves, brain aneurysm clips, artificial joints and dental fillings.

In some of these cases you may still be able to have an MRI, but you should always tell medical staff beforehand if any of these apply to you.  

These MRI magnets may affect any metal implants or fragments in your body – including pacemakers

An MRI can also affect the settings of your device, as each one is programmed specifically for your heart. 

The alternative would usually be to have a CT scan instead as this uses radiation and won’t affect your pacemaker.

This scan involves lying on a bed which passes through a doughnut-shaped opening in a CT scanner to create an image of your heart. 

In recent years “MRI safe” pacemakers and leads have been developed. These can be implanted into new pacemaker patients who we know will need MRIs in the future. 

Mike KnaptonMeet the expert

Dr Mike Knapton is Associate Medical Director (Prevention and Care) at the BHF, overseeing the strategic role in helping patients and the public reduce their risk of heart disease. He remains a GP and works one day a week at a practice in Cambridge.