There are two main types of angina pectoris, stable angina and unstable angina. Key features of these two types are listed below.

Stable angina:

• Also known as chronic angina
• Symptoms are predictable and recognized by the patient
• Often triggered by physical exercise
• Can be caused by emotional stress, exposure to extreme temperatures, heavy meals, alcohol, and smoking
• Relieved by rest or angina medication
  

Unstable angina:

• May be referred to as an acute coronary syndrome
• Symptoms are unpredictable and occur without warning
• Symptoms may be more severe or last longer than usual
• May occur at rest or even during sleep
• Due to a partial or complete blockage in a coronary artery
• Not usually relieved by rest or angina medication