ACS without ST-Segment Elevation: How Fast to the Cath Lab?(acute coronary syndromes)

ACS without ST-Segment Elevation: How Fast to the Cath Lab?

Abstract & Commentary

By Richard Harrigan, MD, FAAEM Dr. Harrigan is Associate Professor of Emergency Medicine, Temple University School of Medicine, Philadelphia Dr. Harrigan reports no financial relationships with companies with ties to this field of study.

Source: DeWinter RJ, et al. Early invasive versus selectively invasive management for acute coronary syndromes. N Engl J Med 2005;353:1095-1104.

It is well-established that patients with acute coronary syndrome (ACS) with ST-segment elevation (STE) on the electrocardiogram (ECG) benefit from early coronary revascularization--preferably by percutaneous coronary intervention (PCI), but also via fibrinolysis. There is evidence that early coronary angiography with PCI (if the anatomy is amenable) may be preferable to a conservative strategy (angiography plus assessment of ischemic territory at risk or failure of medical management) in ACS without STE, but with elevated cardiac troponin levels. These studies, however, did not include the latest additions to the medical management armamentarium, such as the use of clopidigrel and intensive lipid modification therapy.

The authors studied 1200 patients ages 18-80 years from 42 Dutch hospitals enrolled between 2001 and 2003, examining whether an early invasive strategy (angiography within 24-48 hours of randomization, with PCI or surgical intervention as dictated by the findings on angiography) was superior to a selectively invasive strategy in patients with ACS, elevated troponin T levels, and no evidence of STE on the ECG. Patients had to have crescendo or rest symptoms of oronary ischemia that last occurred within 24 hours of randomization. In addition to elevated troponin levels, there had to be either 1) ischemic ECG changes (appropriately stringently defined ST-segment depression or T-wave inversion, or transient STE) or 2) a documented history of coronary artery disease (i.e., previous myocardial infarction, previously positive coronary angiography, or a positive exercise stress test). Exclusion criteria were numerous (see article text), centering on excluding patients with clinical or historical data that made randomization inappropriate, as well as those with recent diagnosis or treatment of ACS. All patients received an optimized medical management regimen including aspirin and enoxaparin for at least 48 hours; those who received PCI were given abciximab. Clopidigrel and aggressive lipid modification also were recommended by protocol.

Those randomized to a selectively invasive strategy were treated pharmacologically, and then went to angiography / PCI only if they exhibited breakthrough angina, hemodynamic or cardiac rhythm instability, or significant ischemia on a pre-discharge exercise stress test. The primary endpoint was the customary composite of death (from any cause), recurrent myocardial infarction (by creatine phosphokinase [CPK] criteria, liberally defined), or rehospitalization with angina within one year of randomization. Notably, patients with elevated CPK levels after PCI were classified as having a recurrent myocardial infarction.