Interpreting new treatment guidelines for non-ST-segment elevation acute coronary syndromes

The American College of Cardiology/American Heart Association Task Force on Practice Guidelines has published recommendations on the diagnosis and treatment of patients with known or suspected unstable angina and non-ST-segment elevation myocardial infarction. The acute ischemia pathway presented in these guidelines encompasses both an early invasive strategy and an early conservative strategy. There are now 4 randomized, controlled trials that have compared the routine early invasive strategy with the selective-invasive or ischemia-guided strategy (Thrombolysis in Myocardial Infarction [TIMI] IIIB, Veterans Affairs Non-Q-Wave Infarction Strategies in Hospital [VANQWISH], Fragmin and Fast Revascularization During Instability in Coronary Artery Disease [FRISC] II, and Treat Angina with Aggrastat and Determine Cost of Therapy with an Invasive or Conservative Strategy [TACTICS]-TIMI 18). The most relevant of these studies to current clinical practice are the FRISC II and TACTICS-TIMI 18 studies. The data from these studies indicate that ST-segment depression or elevated levels of troponin or the MB isoenzyme of creatinine kinase are markers of increased risk and that such patients would benefit from early revascularization. However, the data further suggest that aggressive antiplatelet, antithrombin, and anti-ischemic therapies are also important. Although FRISC II and TACTICS-TIMI 18 support an early invasive approach in most patients (ie, intermediate- and high-risk patients) with non-ST-segment elevation acute coronary syndromes (ACS), all 4 trials support a more conservative approach in those without electrocardiographic changes or enzyme elevations, notably the use of intensive antiplatelet, antithrombotic, and anti-ischemic therapy combined with careful clinical assessment and provocative testing. Patients then undergo catheterization and revascularization only if spontaneous angina occurs or if there is electrocardiographic, enzymatic, or other objective evidence of stress-induced myocardial ischemia. We conclude that tailoring the early initial therapy in hospital to the level of risk is essential to optimizing efficacy and clinical outcomes in this challenging, but common group of ACS patients.