The 2.5 mg strength is also used to treat patients with unstable angina (a type of chest pain that changes in severity) or who are having a myocardial infarction (heart attack): • without ‘ ST segment elevation’ (an abnormal reading on the electrocardiogram or ECG) in patients who are not going to undergo urgent angioplasty (within two hours): angioplasty or ‘ percutaneous coronary intervention ’ (PCI) is an operation to unblock the heart ’ s blood vessels, • with ‘ ST segment elevation’ in patients who are receiving thrombolytic medicines (‘ clot busters’) or who are not about to receive any other treatment to restore blood flow to the heart.