When exercise is unhealthy for the heart

Exercise is generally great for health, but extreme endurance exercise may speed up the development of heart problems in people with a particular genetic mutation, according to a new study.

Arrhythmogenic ventricular cardiomyopathy (AVC), which results from mutations in the genes, is the most common heart condition that causes sudden cardiac death and abnormal heartbeat (or arrhythmias), especially during intense exercise.

The new study found endurance exercise led to earlier onset of AVC symptoms in mice with a mutated version of desmoplakin, a protein that helps maintain the structure of the heart wall.

When people exercise, the heart wall can get overstretched, but in healthy individuals the heart wall doesn’t come a part. However, when there are defects in the proteins that help maintain the structure of the heart wall, as in AVC, the cells in the heart wall cannot withstand the extra stretch from exercise and they detach from each other and die. This can increase the risk of arrhythmias and sudden death.

In its early stages, this condition may not cause any symptoms at all, but affected individuals may still be at risk of sudden death, especially during strenuous exercise.

“Although the exact cause of this condition is unknown, it often appears to run in families,” says Dr. Alan Brown, a cardiologist and director of the Division of Cardiology at the Advocate Heart Institute at Advocate Lutheran General Hospital in Park Ridge, Ill. “If you have mild or no symptoms, it can be difficult to detect.”

When symptoms occur, they may include a sensation of pounding in the chest, lightheadedness, fainting, shortness of breath and abnormal swelling in the legs or abdomen.

“It could be present from birth, and you may not be aware of having the disorder, and that’s why it is very important to tell your doctor if someone in your family has been diagnosed with this condition,” Dr. Brown says. “Your cardiologist can do a screening test such as an echocardiogram and a heart rhythm monitor to check if you have this condition. If you are diagnosed AVC, avoid strenuous physical activity and talk to your cardiologist about the best way to manage exercise and possible abnormal heart rhythms.”

Do you know your risk for heart disease? Take our heart risk assessment here. If you are at high risk, see one of Advocate Heart Institute’s cardiologists within 24 hours.