Coronary artery disease can block arteries, damage or kill part of your heart muscle and weaken your heart’s function. But what if the muscle that seems dead is only dormant or asleep and there’s a way to “wake it up”?
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For some patients, when disease reduces blood flow to parts of the heart, the muscle doesn’t die.
It goes into sleep mode, as though it’s waiting for conditions to improve. This condition is known as hibernating myocardium (heart muscle), says cardiologist Wael Jaber, MD.
You can live with coronary artery disease, but it reduces your heart’s function. When heart muscle dies, scar tissue typically forms in the area.
If the muscle is only dormant, however, doctors can try to restore blood flow by reopening your artery, reviving the muscle and strengthening your heart’s function, Dr. Jaber says.
Waking up the heart muscle
You know your heart muscle is working well when it’s contracting with each beat and getting good blood flow from the arteries.
Once disease reduces blood flow, your heart muscle may hibernate. It reduces its function to the point where it’s barely keeping itself alive.
Your cardiologist can try to restore blood flow and get your heart muscle back to more normal functioning through bypass surgery or by using a stent to open up the artery.
However, Dr. Jaber notes that it’s difficult to distinguish between dead heart muscle and hibernating muscle because there is little or no blood flow in the area.
A hibernating muscle is like a sleeping bear in the middle of winter. They slow their heart rate and respiration. They slow everything. If you look at a dead bear and a hibernating bear, it’s difficult to tell the difference.
If your heart muscle is dead, restoring blood flow will not help.
“We want to make sure first before we open the artery whether the muscle is dead or alive,” Dr. Jaber says. “If you’re trying to reopen an artery to a dead muscle, you’re not doing the patient any favor.”
How do doctors identify dormant heart muscle?
Hibernating myocardium may cause chest pain or shortness of breath in some people. But often there are no symptoms.
That’s why you should ask your cardiologist about hibernating myocardium if you have coronary artery disease — especially if your doctor says you have a weak heart muscle, Dr. Jaber says.
Only a cardiologist or heart failure specialist can assess whether your heart muscle is dormant by using one of these imaging techniques:
- Dobutamine stress echo. This test infuses the heart muscle with a small dose of stimulant to try to wake it up.
- Cardiac MRI. This allows your cardiologist to take a close look at how much blood flow is coming to the muscle as well as directly visualize scar tissue burden compared to healthy tissue.
- Positron emission tomography (PET) scan. This assesses the flow to your cardiac muscle as well as the glucose utilization of your cardiac muscle. Dead muscle does not use glucose whereas hibernating muscle uses glucose.
Ask your cardiologist if one of these tests is right for you prior to any cardiac bypass surgery or stent placement to revive your heart muscle, Dr. Jaber advises, especially if you do not have symptoms of chest pain or chest discomfort.