HCM Researchers Put their Heads Together to Improve Lives of HCM Patients

A recent paper published in the journal Circulation looked at the clinical course of approximately 4,600 HCM patients over the course of more than 24,000 clinical years, which the paper describes as the largest comprehensive cohort of HCM patients ever studied.

This study examined patients from eight high volume HCM centers which aggregated their institutional data into a database known as the Sarcomere Human Cardiomyopathy Registry (or the acronym the “SHaRe” for short). The results of the study showed that, in general, HCM patients are at substantially elevated risk for atrial fibrillation and heart failure, and have significantly higher mortality rates than that of the general U.S. population.

The SHaRe Registry centers that participated in the study are:

  • Brigham and Women’s Hospital, Boston
  • University of Michigan Medical Center
  • Stanford University Medical Center
  • Boston Children’s Hospital
  • Yale-New Haven Hospital
  • Careggi University Hospital, Florence, Italy
  • Erasmus University Medical Center, Netherlands
  • Laboratory of Genetics and Molecular Cardiology, Sao Paulo, Brazil

Working together, these centers, led by Dr. Carolyn Ho, M.D. of Boston’s Brigham and Women’s Hospital, made some significant findings.

Patients with HCM Genetic Mutations Fare Worse HCM patients with a known genetic mutation were diagnosed with clinical disease at a younger age (37.5 years, compared to 51.1 years for patients without a mutation) and were more than twice as likely to experience HCM-related complications and early death than HCM patients who had a non-genetic form of HCM.  Patients with more than one mutation and those who carried a MYH7 mutation were found to have a higher risk of HCM related complications than those with single mutations or those with a MYBPC3 mutation.

HCM Burden Increases Over Time:  The burden of disease and complications increased progressively over time for HCM patients, with most HCM-related complications occurring later in life between the ages of 50-70 years.  In particular, the researchers found that patients who were less than 40 years old at diagnosis had a 77% chance of having an adverse incident such as a cardiac arrest, heart failure, atrial fibrillation, stroke, or death by the time they reached age 60. The most common complications were heart failure and atrial fibrillation.  In contrast, patients diagnosed with HCM after the age of 60 years of age had only a 32% cumulative incidence of such complications by age 70 years.

HCM Mortality is Significant:  Mortality among HCM patients was found to be significantly higher than that of the general U.S. Population. In fact, among young HCM patients ages 20 – 29, mortality was found to be four times higher than that of their healthy counterparts.

The lead author of the paper, Dr. Ho, suggests two major takeaways from this research:

1. A young age of diagnosis and the presence (or absence) of sarcomere mutation(s) should be taken into consideration when forming treatment plans.

2.  Given that the majority of HCM complications occur later in life, there is need for long-term care and follow-up of HCM patients, as well as for the development of new therapies that prevent long term complications such as heart failure and atrial fibrillation.

 

HCM Patients with Scarring More Likely to Have Genetic Mutations

A recent Japanese study found that HCM patients who demonstrated late gadolinium enhancement (LGE) on MRI (which is indicative of myocardial scarring) were more likely to carry a genetic mutation associated with HCM than others who did not show LGE.

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.

Non-Genetic HCM – Reduced Screening?

According to researchers at the University of Michigan, family members of HCM patients who have tested negative for genes associated with HCM and without a family history of HCM will usually be found to be free of HCM during routine family screening.  And, in accordance a recent Australian study,  relatives of these patients may be able to benefit from less rigorous screening protocols.

Patients with a known sarcomere mutation appear to have a different clinical profile, according to the researchers:  they have more hypertrophy; they are younger when diagnosed; they have a higher risk for adverse events;  and they are more likely to have a family history for the condition.

In contrast, when the initial diagnosis is made in a patient who is 50 or older with no known genetic mutations, a negative family history, and sigmoidal septal pattern hypertrophy, reduced family screenings may be appropriate and less burdensome.  In addition, hypertension, large family size with no other affected family members,  less severe hypertrophy, and lack of life-threatening complications related to HCM may provide additional comfort to families of newly diagnosed HCM patients.

The reduced protocol would consist of a single screening of adult family members, with the caveat that if and when any additional family additional member is found to have HCM, a more traditional screening protocol be instituted.

(Note that standard screening guidelines recommend screening of all first-degree family members of patients beginning with adolescence, repeated annually through the end of adolescent growth, and repeated every 3 – 5 years for life.)

 

Could it be Non-Genetic HCM?

When a patient is the only person in the family ever diagnosed with HCM, s/he will often wonder whether their disease is, in fact, genetic.  S/he will also wonder whether it will be necessary for all first degree relatives to undergo serial screenings for the rest of their lives.

In answer to this concern, Australian researchers have recently identified a subset of HCM patients who appear to have a non-familial form of the disease and whose relatives may be candidates for less stringent screening protocols.

The study, just published in Circulation: Cardiovascular Genetics by Dr. Jodie Ingles and Dr. Chris Semsarian, found that this group, having neither genetic mutation associated with HCM nor family history of HCM, comprises approximately 40% of all HCM patients. Non-familial HCM patients are more likely to be older when diagnosed, and they often present with non-asymmetric hypertrophy and hypertension.  And, these HCM patients appear to have a more favorable clinical course, with a better track record of survival from major cardiovascular events.

The researchers point out that by sorting patients into more distinct subgroups, doctors will be able to provide more personalized and evidence-based care to patients and their families.  In particular, their recommendation is that first-degree relatives of non-familial HCM patients need only be screened one or more times in adulthood.  Less frequent follow up surveillance is also suggested, in contrast with the more intensive screening guidelines recommended for family members of patients with familial HCM.