Depending upon the severity and frequency of symptoms, Angina has been divided into two groups:
- Stable angina – In stable angina, the chest pain or discomfort is brought on by exertion, whether physical or emotional (stress), and relieved by taking rest.
- Unstable angina – Unstable angina may have any of the following characteristics:
- Chest pain that occurs at rest or
- Recently started angina (less than two months) with severe and/or frequent attacks (three or more per day) or
- Worsening symptoms in terms of duration, frequency and severity in patients of stable angina.
- Pain that occurs at rest due to sudden spasm (constriction) of the coronary artery (i.e. the artery supplying the heart muscle). This is known as Prinzmetal’s angina and is relatively uncommon.