The results from the Myokardia EXPLORER- MRI sub-study are in, and there is more positive news for mavacamten (formerly known as MYK-461). According to the results of this small 35 patient study, patients who took mavacamten showed reduction of left ventricular size and wall thickness on MRI. These patients also had a reduction in their left atrial volume. All three of these measurements are predictors of poor outcome for HCM patients Additionally, this study found a reduction in certain biomarkers such as NT-proBNP, which indicate heart stress and injury.
MyoKardia (which was recently acquired by Bristol Myers Squibb) hopes that this drug will be approved by the FDA and available to American HCM patients by the end of this year.
For more on the progress of mavacamten, read these previous entries on HCMBeat:
Positive Results for MyoKardia Drug Mavacamten
MyoKardia Announces Positive Result for Mavacamten for Treatment of HOCM
MyoKardia Announces Positive Results from EXPLORER Trial
More Positive Results for MyoKardia Drug
MyoKardia’s EXPLORER Trial Big Success
DISCLOSURES: CYNTHIA BURSTEIN WALDMAN OF HCMBEAT SERVED AS A PATIENT ADVISOR ON THE STEERING COMMITTEE OF MYOKARDIA’S EXPLORER TRIAL. CYNTHIA ALSO SERVES ON MYOKARDIA’S PATIENT ADVISORY BOARD
According to a recently published study by doctors in Copenhagen, Denmark, myocardial crypts (clefts, cracks or fissures in the myocardium) are found in the general population. Therefore, this article concludes that crypts seen on scans of the heart are not necessarily an indicator of HCM and do not warrant further investigation.
This paper is a departure from a 2012 paper by doctors at Tufts, which concluded that myocardial crypts were associated with HCM, and that they were often found in relatives of HCM patients found to be gene positive for HCM, but lacking the hallmark thickening of the ventricle.
Here is an example of what the crypts look like on MRI.
Here is an informative new video from our friend Doug Rachac that nicely explains the safety of MRIs for patients with implantable defibrillators and pacemakers.
I wrote a blog piece about this same issue a few years back. Here it is:
Yes We Scan! ICDs and MRIs
And a few other relevant blog entries here on HCMBeat:
Study Shows MRIs Safe for Pacemaker & ICD Patients
Chapter 3: MRI Safety for ICD & Pacemaker Patients
Safety of MRIs With Abandoned Leads
Last year, Doug wrote this blog entry for HCMBeat specifically about magnets and airports. Read that here:
Blogger Doug Rachac – Magnets and Airports: Should ICD Patients Be Afraid?
And, you can find more about ICDs from Doug on his YouTube Channel.
A recent study by doctors at the Cleveland Clinic suggests that the presence of late gadolinium enhancement (LGE) should be added to the various risk factors currently used to assess patients who are at low or intermediate risk of sudden death. The presence and balancing of these risk factors are used by patients and doctors to determine the need for implantable cardiac defibrillators (ICDs). LGE is an indication of cardiac scar tissue and can be seen on cardiac MRI scans. This study recommended that LGE comprising a total of 15% or more of left ventricular mass be used as an additional risk factor. The study found that this indicator worked equally well when applied to both obstructed and non-obstructive HCM patients.
Interestingly, an earlier but recent study published by Cleveland Clinic doctors found that the risk factors currently in use to determine the need for an ICD fall short as applied to patients with the obstructive form of HCM.
Risk factors in common use today have been propounded by the American College of CardiologyAmerican Heart Association (ACC/AHA) in the U.S., while a different set of guideline and a mathematical risk calculator was promulgated more recently in Europe by the European Society of Cardiology (ESC). You can find more about the ACC/AHA and ESC guidelines here.
A second and related finding of this study by the Cleveland Clinic, known for its large HCM program and high volume of myectomies, was that patients who undego myectomy appear to experience a protective effect from their surgeries. Even when found to have 25% or more LGE, patients in this study who previously underwent myectomy experienced a lower than expected rate of adverse events.
Yet another study has confirmed the safety of MRIs in patients with non-MRI conditional ICDs and pacemakers.
The latest study, from the University of Pennsylvania and published in the New England Journal of Medicine, found no adverse effects from 1.5 Tesla MRI scans performed on 1509 patients who underwent a total of 2103 scans. 58% had pacemakers and 42% had ICDs.
This study confirms previous findings relating to the safety of MRIs in ICD and pacemaker patients reported by HCMBeat here and here.
You can also read my personal experience trying to get a brain MRI in Los Angeles last year here.
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.
Continue reading “Chapter 3: MRI Safety for ICD & Pacemaker Patients”
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.
The long awaited results from the Magna-Safe study were published today in the New England Journal of Medicine, and 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.