Rationale and Timing for Early Invasive Strategy This strategy seeks to rapidly risk stratify patients by assess- ing their coronary anatomy. The major advantages of invasive therapy when appropriate are 1) the rapid and definitive nature of the evaluation, 2) the potential for earlier revascularization in appropriate patients that might prevent occurrence of fur- ther complications of ACS that could ensue during medical therapy, and 3) facilitation of earlier discharge from a facility. 4.4.2.1. Routine Invasive Strategy Timing The optimal timing of angiography has not been conclusively defined. In general, 2 options have emerged: early invasive (ie, within 24 hours) or delayed invasive (ie, within 25 to 72 hours). In most studies using the invasive strategy, angiogra- phy was deferred for 12 to 72 hours while antithrombotic and anti-ischemic therapies were intensified.138,332 337 The concept of deferred angiography espouses that revascularization may be safer once plaque is stabilized with optimal antithrombotic and/or anti-ischemic therapies. Conversely, early angiography facilitates earlier risk stratification and consequently speeds revascularization and discharge but can place greater logistic demands on a healthcare system. 4.4.3. Rationale for Ischemia-Guided Strategy The ischemia-guided strategy seeks to avoid the routine early use of invasive procedures unless patients experience refractory or recurrent ischemic symptoms or develop hemo- dynamic instability. When the ischemia-guided strategy is chosen, a plan for noninvasive evaluation is required to detect severe ischemia that occurs at a low threshold of stress and to promptly refer these patients for coronary angiography and revascularization as indicated. The major advantage offered by the ischemia-guided strategy is that some patients con- ditions stabilize during medical therapy and will not require coronary angiography and revascularization. Consequently, the ischemia-guided strategy may potentially avoid costly and possibly unnecessary invasive procedures. 4.4.4. Early Invasive and Ischemia-Guided Strategies: Recommendations Class I 1. 