According to conservative estimates, 100,000 Canadians may suffer from hypertrophic cardiomyopathy with an estimated prevalence of about one in every 200 to 500 individuals, said Dr. Bobby Heydari, a cardiologist and associate professor of medicine at the University of Calgary, during a webinar hosted by Benefits Canada and sponsored by the Bristol-Myers Squibb Co.
Patients’ mean age of diagnosis is in their 30s, he said, noting HCM is estimated to be an inherited disease in about 60 per cent of cases. For example, a child of an HCM patient has a 50 per cent chance of inheriting the disease, said Heydari, and there’s genetic testing to screen family members.
HCM leads to abnormal thickening of the heart muscle, which makes it more difficult for the heart to pump blood. “A substantial proportion of patients have obstructive hypertrophic cardiomyopathy in whom thickening of the walls of the heart blocks blood flow,” he said.
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The most common symptoms of HCM include fatigue, difficulty breathing and shortness of breath, as well as lightheadedness, dizziness or passing out after physical activity. Some patients experience a fast or abnormal heartbeat and more than 35 per cent suffer chest pain. Historically, the risk of death due to sudden cardiac death was as high as six per cent among patients with HCM, but it’s dropped due to a greater understanding of the disease.
Approximately 80 per cent of patients report limitations to basic physical activities, said Heydari, and when coupled with the worry about their disease, can substantially impact their quality of life and lead to significant stress and anxiety.
In terms of treatment, patients at a higher risk of sudden death can be implanted with a special pacemaker that “will monitor every single heartbeat for the rest of the patient’s life,” he said. If the pacemaker detects a sudden abnormal heart rhythm, it delivers therapies or shocks the patient’s heart.
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There are also medications that can reduce the heart rate and relax the heart; however, some patients don’t respond to or tolerate them. These medications are just for symptom relief and don’t target the underlying disease condition, noted Heydari.
Certain patients may require a highly specialized, complex and invasive surgery — called a myestomy — to reduce the thickness of the heart, he added.
Alcohol septal ablation is a less common procedure for patients who aren’t surgical candidates. It creates a tiny, managed heart attack in the abnormally thickened heart tissue to restore more normal blood flow out of the heart.
Unfortunately, some patients still face severe symptoms, said Heydari, because they don’t respond to existing medications and aren’t candidates for surgery or alcohol septal ablation procedures.
Julie, a patient living with HCM, and her mother shared their stories during the webinar. Julia has a pacemaker and recently had heart surgery in the U.S. due to the need for a specialized surgeon not available in Canada. She still experiences fatigue and shortness of breath, but not to the degree she had before surgery. Julie isn’t able to work due to the severity of her symptoms and her mother can’t work because she’s her daily caregiver.
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Most of the current available medications don’t really address the underlying problem in HCM, said Heydari, noting they only reduce symptoms.
A new class of medications, called myosin inhibitors, specifically target HCM, and was approved by the U.S. Food and Drug Administration in April for obstructive hypertrophic cardiomyopathy. Furthermore, said Heydari, “we believe this medication may also play an important role for patients who have non-obstructive hypertrophic cardiomyopathy.”