best cardiac doctors in yelahanka new town Types of Angina: Stable Angina: Occurs predictably with exertion or stress. Relieved by rest or medications like nitroglycerin. Pain pattern and intensity are usually consistent. Unstable Angina: Unpredictable, can occur at rest, and is more severe or prolonged. Indicates a higher risk of a heart attack and requires immediate medical attention. Variant (Prinzmetal's) Angina: Caused by a spasm in a coronary artery. Can occur at rest, often at night or early morning. Treated with medications like calcium channel blockers or nitrates.