The American Heart Association’s 2022 statistics show that 20% of all heart attacks are subtle, so-called silent heart attacks, that don’t produce the chest-clutching pressure and pain often depicted in films. Some experts suggest the percentage of silent heart attacks is closer to 50%.

“It has been known for a long time that silent heart attacks, identified on an ECG or an echocardiogram ultrasound study, are quite common,” Dr. Joel Kahn, founder of the Kahn Center for Cardiac Longevity in Michigan, tells Newsmax. “Some people can close a heart artery with no symptoms at all or with atypical symptoms of heartburn or shortness of breath that does not prompt them to go to the ER. Nonetheless, silent heart attacks are important and are a reason I check an ECG on all patients I see.”

According to AARP, heart attacks occur when the arteries carrying blood to the heart become blocked, depriving the heart muscle of oxygen and nutrients. Dr. Eduardo Marban, an international leader in cardiology at Cedars-Sinai Medical Center in Los Angeles says that the blockage can cause pain and pressure during a heart attack. In some people, the symptoms go unnoticed.

“It’s not necessarily that there were no symptoms,” says Marban. “It may just be that the patient didn’t recognize them as heart symptoms and wasn’t concerned.” The patient may think they have indigestion, or strained a muscle or feel run-down, explains Marban.

Some people who suffer a silent heart attack may recall they felt shortness of breath, nausea or sweating, dizziness, or a feeling of unease, say experts. Some people truly do not experience symptoms, perhaps because they suffer from diabetes and have neuropathy that interrupts pain signals. Women and older adults are also more likely to have a cardiac event without warning signs, says AARP.

Here are some typical, non-classic symptoms of a silent heart attack, according to Harvard Medical School:

• Shortness of breath
• Weakness
• Nausea or vomiting
• Dizziness
• Back or jaw pain
• Unexplained fatigue

These symptoms may be misdiagnosed even in healthcare settings. Dr. Robert Lager, a cardiologist at MedStar Washington Hospital Center in Washington, D.C., tells AARP that the signs are often confusing and misleading. However, Lager says that symptoms of heart trouble are “not positional.” This means that the pain in your back does not go away when you stretch or move, and the shortness of breath doesn’t subside when you sit down and take it easy.

“That’s a really good rule of thumb,” says Lager. “If you’re not sure if you’re having a symptom, see if you can manipulate it in some way. Can you press on the chest? Can you change your position? Can you stand up or sit down? Does it make a difference, positionally? Because the heart has no gyroscope; it doesn’t know where it is in space. And it doesn’t matter if you put the heart upside down or right side up, it’s going to give you the same signals if it’s in trouble.”

Lager adds that symptoms will get worse due to the lack of nutrient-rich oxygen in the heart. “So, if someone has chest discomfort at rest and gets up and walks around, you’re increasing the heart’s demand for oxygen, and the symptoms usually will get worse if it’s a heart issue,” he explains.

Drs. Marban and Lager emphasize that it is important to be aware of changes in your body, and if symptoms appear out of the blue that are uncommon, have them checked out. If you are prone to indigestion, that feeling of discomfort in the chest after a spicy meal is likely gastrointestinal, but if it’s something you haven’t experienced before, or the symptoms get worse, it may be a sign of a silent heart attack.

Even though the damage has already been done, identifying a silent heart attack can help you get treatment to recover faster and prevent future cardiovascular events, such as heart failure, the likelihood of sudden death, stroke or having another heart attack.