A dangerous type of chest pain caused by reduced blood flow to the heart that requires emergency treatment.

Unstable angina is a medical emergency. It is new or changed chest pain due to a lack of blood flow to the heart. The pain doesn't go away with rest or medicines. Unstable angina is a warning sign of a heart attack.

Symptoms include sudden or new squeezing, pressure, heaviness, tightness or pain in the chest. The pain occurs with low activity or at rest.

Emergency treatment is needed. Treatment includes medicines and a procedure or surgery to open blocked heart arteries.