Just as some people experience no symptoms during silent ischemia, some people can have a silent heart attack without knowing it. Up to 25 percent of heart attacks are symptom-free. The absence of symptoms, however, does not mean the absence of damage to the heart muscle. Unfortunately, people having a silent heart attack are unaware that they need to seek proper treatment immediately, and additional heart-related events or damage may occur.

The majority of people who suffer a heart attack experience symptoms that are often severe and frightening. Recognizing these symptoms and realizing their importance is crucial. The vast majority (90 percent or more) of heart attack-related deaths in patients under age 55 occur outside of the hospital. Medical experts believe this is often due to the patient's lack of recognition of the situation. Younger people tend to ignore symptoms, whereas an older person may be more willing to call 911 at the first sign of trouble. Whatever the case, the sooner the symptoms of a heart attack are recognized and appropriate treatment is administered, the better the outlook for survival – both in the near future and over the long term. Symptoms of a heart attack may include:

Women tend to have different heart attack symptoms than men. Although they may experience shortness of breath, weakness, unusual fatigue and cold sweats, they may not experience chest pain. They may instead feel pain high in the abdomen or chest, or in the back, neck or jaw. They may also experience dizziness. Many women have reported symptoms of unusual fatigue, sleep disturbances, shortness of breath, indigestion and anxiety in the weeks leading up to their heart attack.

Although one or a combination of these symptoms may indicate the onset of a heart attack, they may be due to other conditions as well. As a general rule, it is better to be safe than sorry. If a heart attack is suspected and any of these symptoms are present, this may indeed be a sign of a serious lack of oxygen-rich blood supply to the heart. Emergency medical help should be sought immediately. Physicians usually advise stricken individuals to first call 911, then to chew an aspirin (“regular” aspirin, not non-aspirin pain relievers such as acetaminophen) and wash it down with a glass of water while waiting for help to arrive.