A silent heart attack, also known as a silent myocardial infarction (SMI), is a heart attack that occurs without the classic symptoms like chest pain or discomfort.

It's called "silent" because the person may not realize they're having a heart attack, and the symptoms can be subtle or mistaken for other conditions.

While not as severe as the pain experienced in a typical heart attack, some people may still feel pressure, tightness, or discomfort in the chest area.

Feeling breathless or having difficulty breathing may occur, especially during physical exertion or even at rest.

Unusual tiredness or fatigue that's not relieved by rest can be a sign of a silent heart attack.