Chapter 3: MRI Safety for ICD & Pacemaker Patients

Long awaited results of the MagnaSafe study regarding the safety of MRIs in patients with implantable devices were published in February.   The MagnaSafe study established a multi-center prospective registry for patients undergoing MRI scans despite their having an implanted device not deemed safe for MRI scanning by the FDA.

During the study, MRI scans were performed on a variety of patients who underwent the scans despite the perceived risk.  MagnaSafe ultimately found that these MRI scans were relatively safe, and the risk to patients was low.  However, one shortcoming of the Magna-Safe study was that none of the scans involved in the study involved areas of the body near the implantable device:  instead they involved more remote body parts such as the head, legs or arms.

In May, two posters at the Heart Rhythm Society meeting in Chicago addressed the safety of MRI scans in patients with abandoned leads in their body.

Now, a new study by researchers from the Intermountain Medical Center Heart Institute in Salt Lake City has built upon the findings of the Magna-Safe study and further established the safety of MRIs in patients with non-MRI conditional devices while following the special protocols established by the Magna-Safe study.  The study specifically included patients undergoing scans of the heart, lungs and chest area, all of which had previously been excluded from the MagnaSafe data.

The study looked at 212 MRI exams in 178 patients with an MRI or pacemaker between February 2014 and August 2016. During the 2+ year period of observation, the researchers encountered no problems related to either the implantable devices themselves, or to the 418 leads associated with the devices.  Due the absence of problems, the researchers concluded that these studies are safe for patients.

Now, lead author, Dr. Jeffrey L. Anderson, MD, along with several of the researchers involved in the MagnaSafe trial, have signed and submitted a letter to the U.S. Centers for Medicare & Medicaid Services, asking that it cover medically-necessary MRIs in patients with non-MRI conditional implantable devices and performed under the protocol used in the MagnaSafe study.

[Editor’s note – This is good news for implantable device patients who may need high quality imaging for treatment of various medical problems. You can find a blog entry here describing my own experiences seeking a brain MRI while implanted with an older, non-MRI conditional defibrillator here.]

 

 

Safety of MRIs With Abandoned Leads

Two posters presented at this weekend’s Heart Rhythm Society meeting in Chicago show that patients who have abandoned pacemaker or ICD leads may safely undergo MRI exams.

These posters follow the earlier MagnaSafe study which demonstrated the safety of MRI for patients with pacemakers and ICDs, but which excluded patients with abandoned leads from the findings.

The first, by researchers at Mayo Clinic, included 57 patients with 63 abandoned leads who underwent 70 MRI exams in a 1.5 Tesla machine.  The authors saw no clinical problems and no device malfunction following the scans.

The researchers also monitored blood troponin levels in 35 of the patients following the scans and did not see any elevation which could indicate distress to the heart from the scan.

The second poster, from the University of Pennsylvania, involved 24 patients with abandoned leads who underwent 34 MRI exams.  The results of this study also failed to demonstrate any clinical problems or patient discomfort resulting from the MRI scans.

With any luck, everyone will soon be able to obtain an MRI and will not be denied due to any kind of implantable cardiac device.

For an account of my personal experiences seeking MRI with an ICD, read this.

Study Shows MRIs Safe for Pacemaker & ICD Patients

The long awaited results from the Magna-Safe study were published today in the New England Journal of Medicineand it was good news for pacer and implantable cardioverter–defibrillator (ICD) patients! When proper precautions have been taken, MRIs were found to be safe in patients implanted with certain older pacemakers or ICDs.

In order to study the safety of scanning these patients, doctors set up a prospective registry for patients undergoing MRI in scanners with a magnetic field strength of 1.5 tesla who were scanned despite having a non-MR conditional device (i.e. a device which had not been deemed safe for MRI scanning by the FDA).

MRIs were performed on 1000 patients with pacemakers and 500 patients with ICDs and the results of the study showed that as long as appropriate patient selection and safety protocols were followed, patients had no problems with the MRI scans.

This is indeed good news for those of us with older devices who may be in need of MRI scans. To read about my own experiences and investigation of this issue, read my previous blog entry YES WE SCAN! ICDs and MRIs.

Yes We Scan! ICDs and MRIs

Why MRI is Important:

Magnetic Resonance Imaging, or MRI, is one of the most important tools of modern medicine.  MRIs can be used to evaluate almost every kind of medical issue, from brain tumors to twisted ankles.  They provide clear images, and in some instances, also provide superior visualization.  Because they do not expose the imaging subject to radiation, they are generally preferred over CT scans, even when the two scans would reveal the same information.

MRI in HCM:

In the last several years, MRI has also become an important tool in the evaluation of hypertrophic cardiomyopathy (HCM).  The images resulting from MRI have proven superior in visualizing the size and structure of the heart and, when used with a contrast agent, MRIs are able to show the extent of scarring in the HCM heart.

MRI Hasn’t Been an Option for Many of Us:

MRI has been unavailable to those of us who have an implantable defibrillator or ICD to in order to protect us from sudden cardiac arrest.  Until recently, having an ICD was an absolute contraindication to MRI.  Newer MRI-safe ICD systems have been in use for the last few years, but that still leaves in place the contraindication for those of us who have older ICD units in place.  That problem is that older lead systems that were implanted along with old, non-MR compatible generators may be incompatible with the newer MR compatible technology, and it may not be possible to simply hook up these old leads to a new MRI compatible generator.  And, it is not as easy as you might think to extract old leads.  Scar tissue grows around these leads, making their removal an intricate and dangerous procedure that is best done only in carefully controlled circumstances by highly specialized physicians. Continue reading “Yes We Scan! ICDs and MRIs”

Abandoned Leads Harder to Extract

According to a recent study published in JACC: Clinical Electrophysiology, previously abandoned pacemaker and implantable defibrillator leads which have been capped off and left behind following replacement were harder to extract later.  These abandoned leads also made it more difficult to treat device infections.

When interviewed about the significance of these study results, several physicians knowledgeable in the field further emphasized that lead removal requires special skill and equipment not typical for the average physician who implants cardiac devices.  Hence, patients facing a potential lead extraction should consider their options carefully and seek care from a specialist in lead extraction.

 

Unsuspected AFib Detected in HCM Patients

A recent retrospective study published in the Journal of Cardiovascular Electrophysiology found that atrial fibrillation (AF) occurred for the first time in 16 of 30 patients (53%) of patients with implantable devices being followed at the center conducting the study.

Of the patients experiencing AF for the first time, 14 of 16 (88%) of the patients were not aware of having experienced any clinical symptoms.  As patients age, AF appears to be a common consequence of HCM.  Patients may be caught unaware and unprepared, so monitoring is especially important.