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.]

 

 

Atrial Fibrillation: Treatable HCM Complication

A recent paper by doctors at Tufts University’s HCM Center found that transient episodes of atrial fibrillation (AF) are treatable and do not often progress to permanent AF.

This study found that AF was not a frequent cause of death by heart failure or sudden cardiac arrest.  However, the researchers identified AF as an important cause of stroke in HCM patients.  Therefore, they recommend a low threshold for starting HCM patients on anti-coagulants following an initial AF episode.

Researchers in this study analyzed statistics from 1558 HCM patients, 20% of whom experienced AF.  74% experienced only sporadic episodes, while 26% went on to develop permanent AF.

At the time of publication, 91% of the 277 of the patients included in the sample were still alive and between the ages 49 and 75 years old.

 

 

More is Needed for Women With HCM

A recent study published in the European Heart Journal by doctors from the Mayo Clinic showed that women with hypertrophic cardiomyopathy (HCM) have a statistically reduced rate of survival as compared to men with HCM.

To respond to this inequity, the doctors suggest that the medical system must improve at identifying HCM in the female patient population. Additionally, they propose a lower threshold for the referral of female patients for more advanced therapies.

The study compared by gender the data of 3673 patients (1661 women and 2012 men) who had an initial HCM evaluation at Mayo Clinic between 1975 and 2012.

The data showed that compared to men, women with HCM:

  • present with the disease at an older age;
  • are more likely to have the obstructive form of the disease;
  • have increased diastolic dysfunction;
  • are more likely to have worse cardiopulmonary exercise test results; and
  • are more likely to have pulmonary hypertension.

Strikingly, a female HCM patient’s risk of dying (from any reason – not specifically HCM) was about 6% higher than that for a man over a 5 years period and approximately 11% higher over a 10 year period.

The authors suggest several possible explanations for this discrepancy:

  1. Genetic and endocrine differences between males and females;
  2. Women with HCM do not undergo cardiac screening tests with the same frequency as men and therefore go undiagnosed and untreated longer than men;
  3. Women are less likely to be diagnosed with HCM during routine medical exams and are more likely to be misdiagnosed with hypertension instead of being accurately diagnosed with HCM;
  4. Women are more likely to be on medications for other conditions which could be blamed for vague symptoms; and
  5. Beta-blockers, which were associated with increased survival in this study, were less likely to have been prescribed to women by their referring doctors.

 

Editor’s Note:  As a female HCM patient who is included in this study, I can pretty confidently speak on behalf the other 1660 of us by voicing the hope that researchers identify and remedy any factors which contribute to worse outcomes in female patients.  In fact, we hope for equally good outcomes for all!

 

A Risk Calculator for Sudden Death -Results of HCM-EVIDENCE Study

The HCM Risk–SCD Score

In 2014, the European Society of Cardiology (ESC) introduced a numerical predictor (the “HCM Risk–SCD score”) to assist physicians in identifying those patients at highest risk for sudden cardiac death who would benefit from the implantation of a prophylactic implantable cardioverter-defibrillator.

Using an algorithm generated by the answers to a series of questions, the tool estimates the 5-year risk of sudden cardiac arrest for any particular patient.  You can find the tool online here.

About the HCM-EVIDENCE Study

The reliability of this tool was recently evaluated by the HCM-EVIDENCE study, the results of which were presented at the recent ESC meeting in Barcelona.  This study examined the reliability of the HCM Risk–SCD score in 3,703 patients. The study looked at whether the scores accurately predicted the risk of sudden cardiac arrest (SCA) in particular patients.  The results of the study showed that the tool was useful in distinguishing high from low- risk patients.

Patients who were classified as low risk (whose score predicted less than a 4% chance of a SCA over a 5-year period) had an actual incidence of SCA of 1.4%, while those classified as high risk (with a score predicting a chance of SCA that was greater than or equal to 6% over a 5-year period) had a SCA incidence of 8.9%.

According to the British investigator who led the study, Dr. Constantinos O’Mahoney, “…for every 13 high-risk patients who receive an ICD as recommended by ESC guidelines, one patient could potentially be saved from SCD ...The study also showed that a low score on the HCM Risk-SCD calculator helped avoid unnecessary ICD implants in low risk patients, supporting the 2014 ESC recommendation not to implant ICDs in these individuals.”

Potential Impact of HCM-EVIDENCE Study

Dr. O’Mahoney added that while there is no way to predict and prevent all SCAs, the HCM Risk-SCD calculator help patients to better conceptualize the level of risk which can assist the shared decision-making process .

Dr. Nancy Sweitzer of the Sarver Heart Center at the University of Arizona was interviewed by MedPage Today about the study while at ESC.  Dr. Sweitzer observed that the HCM Risk-SCD calculator could assist in convincing a U.S. health insurer that an ICD is justified in specific cases, since the tool puts the risk of sudden cardiac arrest into quantifiable terms which have now been shown to correlate to actual outcomes.

[Editor’s Note – I tried the calculator out myself.  It suggested that I get an ICD.  I came to the same decision with the advice of several physicians 15 years ago. Though it has never been called upon to do its job, I am glad to have it, just in case.]

Guest Blogger – When a Seizure is not a Seizure – by Wendy Borsari

It’s strange to think that a chaotic arrhythmia in the heart might actually appear to be a seizure caused by something that has gone haywire in the brain, but with sudden cardiac arrest (SCA) this can sometimes happen.

This is the true story of what happened to my daughter.

On April 11, 2017, less than a week after her 14th birthday, my daughter suffered multiple cardiac arrests.  Two of these incidents were thought to be seizures by those who witnessed them.  And it wasn’t only her dance teacher who saw the first event who called it a seizure, but it was also the paramedic who arrived on the scene in time to see the second one.

After her muscles relaxed and she was still, the paramedic informed me that “it appeared as though” my daughter, “could have an undiagnosed seizure disorder.”  He relayed this information even after I had told him that she had Hypertrophic Cardiomyopathy and had had a previous sudden cardiac arrest that presented the same way.

As I listened to him, my mind was reeling.  My daughter had HCM, but could she also have epilepsy? What would this mean for the rest of her life?

Once hooked up to an EKG machine, it became apparent that the cause of my daughter’s events was cardiac; not neurological, but that didn’t make the situation any less horrifying for me or my husband.  While we’ve known for many years that our daughter was at risk of SCA, I had always imagined it would simply look like she fainted, without movement and breathing.

An ambulance rushed us to the local hospital where my daughter proceeded to have three more events, two of which caused her heart to stop completely!

The last time it happened, it took 2 full minutes of CPR to bring her back.

We were then told she needed to be med-flighted to Boston Children’s Hospital but they wouldn’t transport her until they took appropriate precautions in order to prevent another episode while in the air.

So, with a simple shot of local anesthetic to her neck, the on-call cardiac surgeon put a line into her jugular vein and down into her heart that would regulate her heart rhythm and keep her safe.

It was close to midnight by the time we arrived on the rooftop of Boston Children’s Hospital.  The pacer wire which had been placed in her heart worked, and she didn’t have any more events.  For the first time, I felt that she was safe and would be okay.

Two days later she had a dual chamber implantable defibrillator and pacemaker implanted.  We were all eager to go home and put the terrible events of the previous days behind us.

Though I’m still haunted by the events of that night, I’m so thankful that she was able to get the help she needed right away. But what happens to others whose cardiac events go unrecognized, or to the athlete who collapses on the field and looks like he or she is having a seizure?

I am sharing our story with the hope that it might bring awareness and possibly even save a life.

What Does Cardiac Arrest Look Like?

A person who is having a SCA will often become rigid with muscles seizing, as though suddenly made of stone. With SCA, breathing is non-existent.  You will sometimes hear a sound that is something like a cross between a loud snore and a gasp. This is called agonal breathing, which is actually not breathing at all. Agonal breathing is the brain’s attempt to override the body as it’s being starved for oxygen.  Agonal breathing is present roughly 40% of the time in a cardiac arrest, occurring during the short window of time that an AED shock would still be effective.

With a seizure, there will probably still be breathing, even though it may come in gasps.

It terrifies me to think that a bystander who witnesses a collapse might not reach for the nearest automatic external defibrillator (AED) if the event looked the same as my daughter’s.  Instead, they might call 911 and stand helplessly by, waiting for the paramedics and assuming that there was nothing to be done.

The events of that terrifying night in April will be with me for the rest of my life. I am forever changed by what I saw, and by the sounds I heard coming from my daughter.

However, if sharing my story with others might possibly save someone else’s son or daughter, it might help those awful sounds to fade from my dreams.

 

For more on how to distinguish a SCA from a seizure, see this link.  Please note that this page contains graphic videos which may be disturbing.

About Wendy

Wendy was diagnosed with Hypertrophic Cardiomyopathy at the age of 24. She comes from a family with a long history of HCM and sudden cardiac arrest. There have been 8 heart transplants within her immediate and extended family.

Wendy has 2 children, both of whom have been diagnosed with HCM. Wendy’s daughter was diagnosed at birth and her son at the age of 15.

Wendy now works with the Sarcomeric Human Cardiomyopathy Registry (SHaRe) and educates people about genetic cardiomyopathy through the website www.theshareregistry.org and through her “Affairs of the Heart” patient conferences held around the United States.

You can email Wendy at:  wborsari@shareregistry.org

Could Your Fitbit Detect AFib?

The same Fitbit you wear to count your steps may soon have an additional purpose:  it could detect atrial fibrillation.

Atrial fibrillation is an irregular heartbeat which could cause a stroke if not properly treated.  Yet, it often goes unnoticed by a person experiencing it.

According to this story in Time, Fitbit is  developing software which would enable its existing trackers to detect afib, and thus allow time for appropriate action before it is too late.

This technology could be of great benefit to heart patients.  Not only does the Fitbit encourage you to exercise, it might just save your life!

Multiple Mutations in HCM

A recent paper by researchers in Australia, published this week in Circulation: Cardiovascular Genetics, found more than one rare HCM gene in 4% of patients in a 758 patient sample group.

The researchers found that those patients with multiple rare HCM genes tended to present with HCM at a younger age, were more likely to experience cardiac arrest or death from other causes, and were more likely to require a heart transplant.

In general, few patients have multiples of mutations commonly associated with HCM.  See this Canadian study from April of this year which found that multiple mutations were less prevalent and harmful than previously thought.

Pig Hearts on Horizon for Transplant Patients?

According to this New York Times article, the genetic repair process CRISPR may make it possible for pig hearts to replace human hearts.  If this technology works, it would be good news for those awaiting transplant.

Currently, there are limited organs available with strict protocols for eligibility.  A new source of suitable donor organs would be a great advance for heart transplantation.

Encouraging Results for MyoKardia HCM Drug

MyoKardia’s stock prices jumped today after their recent Stage II trial of the experimental drug mavacamten (formally known as MYK-461)  demonstrated a statistically significant reduction to left ventricular outflow tract gradients as well as improvement to aerobic capacity in patients with obstructive hypertrophic cardiomyopathy.  

Of the 10 patients who completed the study, 8 saw their gradient reduced to normal levels after 12 weeks on the drug.  The study also showed improvements in both peak oxygen consumption (peak VO2) and New York Heart Association classifications:  7 patients moved up one NYHA class while 2 patients improved by two classes.

The drug seemed to have mild to moderate side effects, though one patient was forced to drop out of the trial due to a recurrence of atrial fibrillation which necessitated discontinuation of mavacamten and a return to anti-arrythmic drugs which had been discontinued due to participation in the trial.

MyoKardia hopes to enroll between 200 and 250 patients in its next phase trial (Explorer HCM) which it plans to begin before the end of 2017.

MyoKardia also plans a clinical trial of mavacamten in non-obstructive HCM patients in the second half of 2017.

For more information on MyoKardia and  recent drugs being developed for HCM read these past blog entries:

MyoKardia HCM Drug Has Success in Cats

End of the Road for Eleclazine and Liberty HCM Study

HCM Drug Trial Advances to Next Round

Drug for Non-Obstructive HCM Moves Along

CRISPR Eliminates HCM Gene !

Scientists, in a follow up to three earlier, less successful, Chinese experiments, have for the first time used a recently developed gene editing process known as “CRISPR” to remove a genetic defect from a human embryo.  The specific defect that the scientists targeted was a mutation in MYBPC3, a common genetic cause of hypertrophic cardiomyopathy (HCM).

What Happened in the Study?

The study authors consisted of a multi-national team of geneticists, cardiologists, fertility experts and embryologists.  Led by Dr. Shoukhrat Mitalipov of Oregon Health Sciences University, in collaboration with researchers at the Salk Institute in La Jolla, CA, China and South Korea, the researchers were able to largely remove the HCM gene MYBPC3 from very early stage human embryos.

Their research involved using eggs from 12 healthy female donors, and sperm from a male HCM patient with the MYBPC3 gene.  When gene-editing components were introduced to the egg along with the sperm, prior to fertilization of the egg, approximately 3/4 of the embryos repaired themselves using the DNA blueprint provided by the normal, non-mutated copy of the gene from the unaffected female.  This was somewhat surprising to researchers, who had theorized that cells would replicate using a blueprint from the repaired paternal gene – not the healthy gene of the mother.

Ultimately, genes were corrected in 42 of 58 embryos, constituting 72.4% of the total, a higher proportion than expected, and far more than any correction shown in previous experiments.

Implications for the Future

This technique is still far from general usage and will require further study and refinement.  And, currently it is not legal in the United States since the Food & Drug Administration currently prohibits medical gene editing which would impact future generations.

However, it would be possible for this technique to be used alongside current technology to assist families with genetic diseases like HCM.  If used in conjunction with pre-implantation genetic testing and in-vitro fertilization (PGD), the technique could repair the large proportion of embryos (roughly 50%) which must be discarded due to genetic defectiveness.

While there are critics who say that this technology will lead to “designer babies” and that it creates troubling ethical issues for society, most HCM patients believe that it provides a ray of hope, so that hopefully one day, in the not-too-distant-future, our children and grandchildren will be free of the affliction that has permeated our lives, as well as the lives of our siblings, our parents, our aunts and uncles, our cousins, our grandparents, and our great-grandparents.

Story Links:

As this story was reported by all major news sources, links to many of the articles can be found below.

Nature

The Atlantic

New York Times

Washington Post.

NPR

LA Times

Los Angeles Times – Q&A video clip with lead study author Shourkhrat Mitalipov

The Guardian

USA Today

MIT Technology Review

Gizmodo

Boston Herald

LA Times article regarding ethics -response to first article

NOTE THAT APPROXIMATELY A MONTH AFTER THE PUBLICATION OF THIS ARTICLE, THE RESULTS HAVE BEEN CALLED INTO QUESTION BY OTHER SCIENTISTS.

See this article in MIT Technology Review, this article in Science Magazinethis article in Nature, and this article in The Scientist, all of which cite this article in BioRxiv which poses alternative theories for the results claimed by the original paper.