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How do viruses trigger heart damage?

Dr. Slava Epelman is deciphering immune reactions that can lead to heart failure
 A woman wearing a gray sweater blows her nose into a tissue.

When you catch a virus like a cold or stomach bug, you usually recover quickly. But sometimes viral infections can have devastating consequences. 

Ashley and Frank Greco of London, Ont., were shattered when their newborn son, Emmett, died suddenly from myocarditis, an inflammation of the heart muscle. He was only eight days old. While it’s not clear how Emmett developed myocarditis, it is often triggered by a viral infection. 

Since that tragedy, the couple have organized a walk to raise awareness of myocarditis and to raise funds for research towards a cure. 

Dr. Slava Epelman is a Heart & Stroke researcher working to understand how and why some viral infections lead to heart damage, so stories like Emmett’s could be prevented.

Immune cells have different jobs

Dr. Epelman’s team discovered that immune cells have different roles when the heart is attacked by a virus. Some cells work to repair tissue damaged by the infection, while others fight off infection.

But these fighting cells may actually contribute to further damage by causing inflammation in surrounding tissue, even after a virus has been cleared. This results in myocarditis symptoms such as shortness of breath, exhaustion and feeling weak, which can linger for weeks, or even months.

“You feel crummy after you have an infection, and you just don’t get better,” explains Dr. Epelman, a cardiologist at the Toronto General Hospital and recipient of a 2015 Heart & Stroke Clinician-Scientist award.

 Dr. Slava Epelman

It’s a fine balance and we’re trying to understand it.

Dr. Slava Epelman Heart & Stroke researcher

While most cases of myocarditis in adults clear up without complications, a severe or prolonged case can leave you vulnerable to other problems like high blood pressure or coronary artery disease. And in turn these conditions can lead to developing heart failure more rapidly. “Our ultimate goal is to understand how the viral infection contributes to this process,” says Dr. Epelman.

He hopes this could lead to new therapies that would accelerate the repair of heart tissue. The key will be turning on immune cells to quickly eliminate a virus, and turning off the cells that are causing heart damage after the virus clears. 

“It’s a fine balance and we’re trying to understand it,” says Dr. Epelman.

Babies at highest risk

A sad reality of myocarditis is that the very young, like baby Emmett, are most at risk.

“Their immune system is designed to help the body grow rather than help fend off infections,” says Dr. Epelman. “It’s a benefit but at the same time leaves them unable to clear the virus well.”

Emmett’s mother, Ashley, says he was taken away quickly and unexpectedly, as the symptoms can be subtle in babies. Dr. Epelman hopes his work can change the lives of families like Emmett’s that have been affected by myocarditis. 

Viral infection is believed to be a major, yet unappreciated factor in the development of heart disease, in both adults and children. “Without contributions to Heart & Stroke, many researchers — the whole floor I work on — would be significantly impacted,” says Dr. Epelman.