Unstable angina is the most dangerous of the three types of angina. This common form of angina is typically caused by blood clots that partially or totally block a coronary artery; symptoms are often a sign that a heart attack could occur soon. Unlike stable angina, this type of angina does not follow regular patterns, which may make it difficult to pinpoint.
Angina pectoris (or angina for short) is chest pain or discomfort that occurs when the heart muscle is temporarily not getting enough oxygen-rich blood. A bout of angina is not a heart attack, but it means that you're more likely to have a heart attack than someone who doesn't have angina.
There are three types of angina:
The most common types of angina are stable angina and unstable angina.
Unstable angina is a dangerous condition that requires emergency treatment. It occurs more often in older adults and is a sign that a heart attack could occur soon. In fact, 10 percent to 20 percent of people with unstable angina symptoms will have a heart attack. Unlike stable angina, unstable angina can occur without physical exertion and is not relieved by rest or medicine.
In order to understand angina, it is often helpful to understand how the heart and the coronary arteries function. Like any muscle, the heart needs a constant supply of oxygen and nutrients, which are carried to it by the blood in the coronary arteries. Similar to other muscles, the harder the heart is working, the more oxygen and nutrients it needs. However, the coronary arteries can become narrowed or clogged, which can decrease the amount of blood that goes to the heart muscle. When the coronary arteries cannot supply enough oxygen-rich blood to the heart, angina symptoms can occur.