In stable angina, chest pain follows a predictable pattern. It usually occurs after extreme emotion, overexertion, a large meal, cigarette smoking or exposure to extreme hot or cold temperatures. Symptoms usually last one to five minutes, and they disappear after a few minutes of rest. Stable angina is caused by a smooth plaque that partially obstructs blood flow in one or more coronary arteries.
Acute coronary syndrome (ACS) is much more dangerous. In most cases of ACS, fatty plaque inside an artery has developed a tear or break. The uneven surface can cause blood to clot on top of the disrupted plaque. This sudden blockage of blood flow results in unstable angina or a heart attack (myocardial infarction). In unstable angina, chest pain symptoms are more pronounced and less predictable compared to stable angina. Chest pains occur more frequently, often at rest, and last several minutes to hours. In addition, people with unstable angina frequently sweat profusely at times and develop aches in the jaw, shoulders and arms.
Many people with coronary artery disease, especially women, do not have any symptoms or have unusual symptoms. In these people, the only sign of coronary artery disease may be a suspicious change in the pattern of a test called an electrocardiogram (EKG), which records the heart's electrical activity. The test can be done at rest or during exercise (exercise stress test). The stress test is able to detect the problem in the coronary artery because exercise increases the heart muscle's demand for blood. The body can't meet this demand when the coronary arteries are significantly narrowed. In areas of the heart affected by narrowed coronary arteries, the heart muscle starves for blood and oxygen, and its electrical activity changes. This altered electrical activity is reflected in the patient's EKG results.
If the problem is not discovered, the first symptom of coronary artery narrowing may be a heart attack. A person who has a heart attack has a 15% chance of dying before receiving medical attention.
