Breakthroughs in the Treatment of Hypertrophic Cardiomyopathy

As we age, we want to ensure our heart stays healthy.

We can control many things, such as our diet, exercise, healthy weight, and not smoking. Hypertrophic cardiomyopathy (HCM), however, is a genetic heart condition that affects many people in America and around the world.

What is hypertrophic cardiomyopathy?

HCM occurs when the walls of the left ventricle, one of the four chambers of the heart, grow thicker and stiffer. In some patients, this can make it difficult for the heart to pump blood efficiently and reduces the amount of blood brought in or pumped out with each heartbeat.

Though HCM is a genetic condition, it usually doesn’t get diagnosed or present symptoms until around middle age. But it can be diagnosed in children and people in their 80s, according to Omar Wever-Pinzon, M.D., director of the advanced heart failure treatment and recovery team at the University of Miami Health System.

According to the American Heart Association, about one in every 500 people in the U.S. has HCM. Dr. Wever-Pinzon says that the known prevalence of the disease has increased in recent years as diagnostic tools have improved, and it may even be as high as one in 200 people. “The disease is underdiagnosed, and many people with HCM don’t even know that they have it,” he says.

Obstructive vs. nonobstructive HCM

Among people with HCM, about two-thirds will have the obstructive type, where blood flow is blocked or reduced from the left ventricle to the aorta, and one-third have the nonobstructive type. Dr. Wever-Pinzon says that the majority of those with obstructive HCM experience symptoms. About 10% of those with nonobstructive HCM experience symptoms. These symptoms may include:

• Abnormal heart rhythm (arrhythmia)
• Shortness of breath
• Chest pain
• Fatigue
• Dizziness, lightheadedness or fainting
• Swelling in the legs, feet, or neck veins

Over time, HCM can lead to additional health complications, including atrial fibrillation (a-fib), which can in turn increase the risk of blood clots and stroke. Heart failure or sudden cardiac arrest are other potential outcomes of untreated HCM in some people.

How to treat HCM

Traditionally, the treatment of HCM has involved medications. This includes beta-blockers, calcium channel blockers, heart rhythm medicines or blood thinners.

In other cases, doctors may recommend surgery to remove or shrink the thickened heart tissue and improve blood flow. Devices such as an implantable cardioverter-defibrillator (ICD) may also be recommended. For end-stage heart failure, when other medicines and treatments no longer work, a heart transplant may be an option for some patients.

Treatment breakthroughs

Dr. Wever-Pinzon says that a better understanding of the molecular basis of the disease allowed us to identify new targets for this condition. A relatively new class of medicines known as myosin inhibitors is revolutionizing the approach to the treatment of HCM. One, mavacamten (Camzyos), is FDA-approved for the treatment of patients with obstructive HCM with symptoms, and other drugs under the same class are undergoing evaluation.

“Though more research is needed in regard to long-term outcomes, imaging-based studies have shown that myosin inhibitors can reduce the thickening of the heart muscle wall in the short term,” he says. “Whether that leads to sustained changes is yet to be seen, but there is definitely some promise there.”

Another novel treatment option is gene therapy.

According to Dr. Wever-Pinzon, the promise of gene therapy for HCM is exciting and may change the face of treating the disease in the future. Unlike traditional treatments, which address the symptoms of HCM, gene therapy aims to modify the causes of the disease at a genetic level. They may normalize in quantity or quality the protein production that, when deficient, would lead to the thickening of the heart’s walls.

In the future, myosin inhibitors and gene replacement therapy may be joined by other drugs in its class that can reduce the symptoms and future complications for people living with HCM.

Dr. Wever-Pinzon says that clinical trials are ongoing. The Hypertrophic Cardiomyopathy Program at the University of Miami, which he leads, is currently in the process of onboarding some of these trials to further the research into these promising treatments and provide his patients with access to these novel approaches.

Wyatt Myers is a contributor for UHealth’s news service.

Tags: cardiovascular disease, Dr. Omar Wever-Pinzon