More than 30 years ago the hypothesis of an interventional approach in patients with unstable angina or non–ST-segment elevation myocardial infarction (NSTEMI) was considered only after a "cooling-off" period. This negative attitude was in part justified by the lack of effective antithrombotic adjunctive therapies and devices in the management of lesion containing thrombus and the subsequent early hazard of percutaneous coronary intervention (PCI). The delay—many days or weeks after hospital admission—to interventional treatment could result in an apparent stabilization of the acute coronary syndrome (ACS) with a high incidence of early recurrent ischemia or nonfatal myocardial infarction (MI) in the more favorable cases or in a definitive "cooling" of the patients.
During this long period many trials comparing an early invasive strategy with a conservative strategy in patients with unstable angina or NSTEMI have produced conflicting results that have delayed the current general consensus regarding the benefit of an early invasive strategy, which is more evident in high-risk patients and mainly driven by the decrease in MI and the need for percutaneous or surgical coronary revascularization. This troubled history might be explained at least in part by the design of most studies that randomized patients before cardiac catheterization and the use of a wide temporal windows—from 24 to 48 h to 5 days—for the definition of "early" intervention. Randomization before cardiac catheterization resulted in the enrolment of a high percentage (>30%) of patients who did not receive coronary revascularization, because of mild or absent atherosclerotic coronary artery disease in most of them, making the comparison of an early invasive strategy versus a conservative or a delayed invasive strategy in selected patients distorted by the high number of patients at low risk of events whatever the strategy adopted. The use of temporal windows as long as 24 to 48 h to several days...
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