Many HCM patients, perhaps even the majority, are currently unable to identify the specific gene behind their HCM through genetic testing. Despite this obvious difference, family screening, risk stratification and treatment standards are no different for patients who carry a HCM gene and those who do not have identified gene(s).
A recent article published in Circulation suggests that there ARE differences which should result in different treatment for this subset of patients.
In particular, non-sarcomere positive patients:
- have a better prognosis, with lower rates of heart failure, sudden death, atrial fibrillation and stroke
- Have lower incidence of family members affected by the disease
- Are more likely to have additional medical conditions such as obesity, hypertension and diabetes
The article by Dr. Hugh Watkins, a British HCM and genetic expert, suggests that:
- the risk to first degree relatives of this type of HCM patient is less than 50% and therefore, there is less need for repeated screening of relatives
- Hypertension should be treated more aggressively in these patients.
Read more about non-genetic HCM here and more about screening these patients here on HCMBeat.
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.)