Patients with prolonged or recurrent chest pain may have a condition called unstable angina or suffer a certain type of heart attack called non-ST elevation myocardial infarction. These conditions can be managed with two main treatment strategies. Several studies have been done to determine which strategy is superior. In one strategy, the routine invasive strategy, all patients have a catheter inserted to image their coronary arteries and look for atherosclerotic narrowing. If a significant narrowing or complicated plaque is found then the artery may be dilated by means of a balloon catheter that is inserted and inflated across the narrowing. The patency of the vessel is maintained by insertion of a metallic stent. In some cases, the narrowing will not be amenable to this approach and surgery to bypass the narrowing is required. In the other conservative strategy, patients are initially treated with drugs and only those who suffer more chest pain while receiving the drugs or who demonstrate evidence of atherosclerotic narrowing as suggested by other non-invasive tests, such as stress testing or imaging, undergo coronary angiography and revascularization if indicated.
There has been debate as to which strategy is better. The invasive strategy reduces the incidence of further chest pain or rehospitalization. Also, long-term follow up from three studies suggests that it reduces the risk of having a heart attack in the three to five years following the event by 22%. However, the invasive strategy is associated with a doubled risk of procedure-related heart attack and increased risk of bleeding. Hence, available studies suggest that the invasive strategy may have particular benefit in patients who are at higher risk for recurrent events and that patients at low risk for a recurrent event may not derive benefit from invasive intervention. The level of risk that warrants intervention requires considerable further research.