A heart attack usually has a familiar list of symptoms: chest pain, difficulty breathing, and a feeling of heaviness in the chest.

But these are not the only symptoms nor should they occur with every heart attack

Silent heart attacks, officially known as silent myocardial infarction (SMI), are "silent" because the symptoms are so mild that people often do not realize they have occurred, writes The Insider.

But that does not mean you can ignore a silent heart attack and medical experts say it is just as dangerous as the classic one.

Here's how to tell if you have a silent heart attack and what to do about it.

What is a silent heart attack?

A 2015 study published in the journal Circulation with nearly 10,000 participants compared silent and classic heart attacks and found that silent ones accounted for almost half of all heart attacks.

Nicole Weinberg, a cardiologist at Providence Saint John Health Center, says there may be situations where people have no symptoms but have a silent heart attack.

However, there are some mild and discrete symptoms that are difficult to recognize.

These include fatigue, heartburn, chest, back or mouth discomfort, and breathing problems, according to the American Academy of Family Physicians (AAFP).

A classic heart attack may have similar symptoms, but it also often involves a feeling of pressure or pain in the chest, arms, neck, back and / or mouth.

Moreover, the symptoms of a quiet heart attack can be easily replaced with something else, such as indigestion, strenuous exercise or even toothache.

Although these symptoms do not seem to be a sign of anything serious, Weinberg says a quiet heart attack is just as serious as any other heart attack.

Why are silent heart attacks dangerous?

Heart attacks - silent or classic - occur when not enough blood reaches the heart, which increases the chance of a heart attack again, as well as the chance of heart failure.

"It is essential to open a blocked coronary artery as soon as it is blocked, so that we are not in a situation where there is reduced blood flow," Weinberg said.

While the study found that silent heart attacks are more common in men than women, it was also found that women are more likely to die from the consequences.

Researchers have also found that silent heart attacks are more common in older people with diabetes.

For example, in a study published in 2012 in the Journal of the American Medical Association, 14% of 337 participants with diabetes experienced a silent heart attack compared to 9% of the same population who had a classic heart attack.

How to distinguish the signs of a silent heart attack?

If you think you may have symptoms of a heart attack, you should call an ambulance immediately.

However, in most cases of silent heart attack, the symptoms are so mild or even non-existent that the person usually does not think that calling an ambulance is absolutely necessary.

The diagnosis is often made during a routine systematic examination or during a visit to the doctor due to long-term symptoms such as fatigue, shortness of breath and indigestion.

Risk factors are the same for classic and silent heart attacks: family history of heart attacks, age, choice of lifestyle habits like smoking or insufficient exercise, obesity and conditions like high blood pressure, cholesterol high and diabetes.