A recent study by Canadian researchers published in the American Heart Association journal Circulation found a much lower incidence of  HCM related sudden death than expected.  The study included deaths in individuals that occurred between the ages of 10 and 45 in the Canadian province of Ontario between 2005 and 2016.  According to lead author Dr. Paul Dorian of the University of Toronto, the expectation was that 1 incident of sudden cardiac death would be identified in every 100 to 200 people who had HCM.  Instead, researchers found that the likelihood of sudden death of HCM patients was instead only about 1 in 3,000 people/year.

The study also found that found 7 in 10 HCM-related sudden deaths occurred in people not previously diagnosed with the condition.  Men had more than 5 times the risk of sudden cardiac death than women, and most deaths occurred during rest or light activity: only about 17% happened during or immediately after exercise. 

As a result of the study, according to Dr. Dorian, “our findings allow us to lower the temperature on our degree of worry about the condition.”

Another clinical take away from the study, according to the researchers, is that current exercise guidelines for HCM patients may be too restrictive.