Several years ago, researchers from the University of Virginia (UVA) and the University of Oxford announced a joint project involving a large international registry of hypertrophic cardiomyopathy (HCM) patients to facilitate research into HCM. Backed with funding from the National Heart Lung and Blood Institute, this project, known as the HCM Registry, includes data from 2,750 patients with HCM at 44 sites in six countries.
This week, researchers from UVA announced their first findings from this registry which suggest that HCM patients can be separated into two basic groups:
- Patients with a known genetic mutation who are not obstructed but have scarring of the heart muscle;
- Patients who do not have a known genetic mutation and do not exhibit scarring, but who do have a significant amount of obstruction to blood flow.
According to Dr. Christopher Kramer of UVA, this information should provide doctors with information that allows them to better assess the degree of risk to any particular patient, and to help inform a treatment strategy for each patient based on his or her unique profile.
A recent study by doctors at Toronto’s Hospital for Sick Children suggests that current screening guidelines for children from HCM families are inadequate and should instead recommend earlier screening exams. In the U.S., screening begins at age 12 pursuant to American College of Cardiology (ACC)/American Heart Association (AHA) guidelines. In Europe, screening begins at age 10 pursuant to the European Society of Cardiology (ESC) guidelines.
In particular, the doctors found that out of 524 children who underwent
family screening prior to age 18, 9.9% showed evidence of HCM at first screening and only 1.1% of these children were symptomatic. An additional 28 (5.4%) children developed HCM over 3 years of follow-up, while 41% of major cardiovascular events [death, sudden cardiac death, or need for major interventions such as myectomy, ICD implantation, or heart transplant] occurred in children before the age of 10 year. Therefore, the doctors suggest that certain children appear to be at elevated risk and should be followed from earlier ages.
In particular, the study showed that children at greatest risk are:
- have a pathogenic genetic mutations in MYH7 or MYBCP3
- Have a family history of sudden cardiac death
A companion editorial by Dr. Christopher Semsarian of the University of Sydney in Australia and Dr. Carolyn Ho of the Brigham and Women’s Hospital in Boston points out that even under current guidelines, while screening is optional before age 12 (2011 ACC/AHA Guidelines) or age 10 (2014 ESC Guidelines), screening should still be considered if there is a particularly malignant family history, the child is an athlete or if there are symptoms or other indications of disease.
Semsarian and Ho note that even though screening tests (echocardiograms and EKGs) and non-invasive, there can be both monetary and emotional costs to the family resulting from screening. Hence, they recommend individualization in screening as opposed to a blanket rule; especially given that information relating to genetic status, gender and family history are easily available. Each family situation should be assessed individually, taking into consideration their own set of unique risk factors and their tolerance for risk.
Editor’s Note: HCMBeat recently highlighted this study from the U.K. which similarly concluded that the age of screening children in HCM families should be lowered.
According to a paper published last week in JAMA Cardiology, doctors at Tufts University’s HCM Center have been able to identify 95% of their patients at high risk of sudden cardiac death (SCD) from HCM. Tufts applied an updated and modified version of the risk factors enumerated in the American College of Cardiology/American Heart Association Guidelines promulgated in 2011.
Continue reading “Docs Reliably Identify HCM Patients in Need of ICDs”
A recent study by doctors at the Cleveland Clinic found that current guidelines used to assess risk of sudden cardiac death (SCD) in HCM fall short when applied to the population of patients with the obstructive form of HCM (HOCM).
The study looked at both the European Society of Cardiology (ESC) and American College of Cardiology (ACC)/American Heart Association (AHA) guidelines, and found that both sets of guidelines came up short in predicting SCD. In particular, the study found that patients who had previously undergone myectomy had a reduced risk of SCD that is not accounted for in existing risk models.
Conversely, the study found that patients with atrial fibrillation had a higher risk of SCD, which is also not reflected in the existing risk models.
A companion editorial by Dr. Harzell Schaff of the Mayo Clinic explains the likely reasons for the myectomy findings, while a second accompanying editorial by Dr. John Jefferies of Cincinnatti Children’s Hospital (who has recently accepted an appointment at the U. of Tennessee Health Science Center in Memphis) maintains that the ESC and ACC/AHA guidelines should be changed to reflect the lower SCD risk following myectomy.
Click here for previous coverage of the ESC and ACC/AHA guidelines. If you would like to try out the ESC Risk Calculator for yourself, click here.
A recent Canadian study found that children with HCM who carry a single mutation in the MYH7 gene or who have multiple HCM-causative genetic mutations are at increased risk of major adverse cardiac events when compared to children who carry a single mutation in another gene.
Of the 98 gene positive children in this study, those with a MYH7 mutation or those with multiple mutations were more likely to need a myectomy or an ICD or to experience a sudden cardiac arrest or a heart transplant when compared to children with other HCM causative mutations.
The article also suggests that current screening protocols which recommend clinical and genetic screening for HCM beginning at age 12 may be insufficient.
A recent study published in the American Journal of Cardiology found that the standards propounded by the American College of Cardiology Foundation with the American Heart Association (ACC/AHA) were superior in predicting which patients would benefit from an implantable cardiac defibrillator (ICD) compared to the calculator set forth by the European Society of Cardiology (ESC). According to the study, the use of the ESC tool will result in more high-risk patients going unprotected against sudden death.
Specifically, the study found that out of a group of 288 HCM patients, 14 who experienced aborted sudden cardiac arrest (or 43%) would not have qualified for an ICD under the ESC risk model compared to 7% of patients under the ACC/AHA guidelines.
The ACC/AHA guidelines are:
A companion editorial by Dr. Andreas S. Barth pointed out the shortcomings of both models, and reaffirmed the necessity for shared decision making between physicians and patients. Dr. Barth also expressed hope that a more accurate predictive model will evolve, though he acknowledged the impossibility of designing a model which could predict future events with certainty.
**Because so much HCM information was presented at the Summit, this is the second of multiple blog entries. Stay tuned to HCMBeat for more highlights from the HCM Summit. To see Part I of this series of highlights from the HCM Summit VI, click here.**
The 6th International HCM Summit was held October 27, 28 and 29th in Boston, Massachusetts. This symposium brings together HCM professionals from around the world who are there to learn about and discuss the latest developments in the treatment of HCM.
The symposium was organized by long time HCM expert Dr. Barry Maron and his son, Dr. Martin Maron. Both Marons are now affiliated with Tufts Medical Center’s Hypertrophic Cardiomyopathy Center.
What follows are summaries from selected talks presented at the meeting. The presenter and their hospital affiliation are noted below, along with the topic of their presentation. When possible, you may access the presenters’ slides via hyperlink by clicking on the name. (Note that not all presenters made their slides available).
Continue reading “HIGHLIGHTS FROM THE INTERNATIONAL HCM SUMMIT VI, PART II”