José G. Díez， MD， FACC， FSCAI Assistant Professor of Medicine Baylor College of Medicine Interventional Cardiology Texas Heart Institute Houston， Texas， U.S.A.

The ACC and AHA Task Force on Practice Guidelines has revised and updated its 2002 guidelines for managing cardiovascular disease， particularly UA and NSTEMI， which are a leading cause of US visits to the ED and hospitalizations (669，000 for UA and 896，000 for MI in 2004). Because UA and NSTEMI are so widespread， many healthcare clinicians other than cardiovascular specialists will encounter patients with UA/NSTEMI， mandating guidelines for proper evaluation and management. It has been described that compliance with the guidelines does improve clinical outcomes. (CRUSADE)

The American College of Cardiology (ACC) and the American Heart Association (AHA) have updated their 2002 Guidelines for the Management of Patients with Unstable Angina (UA)/Non-ST-Elevation Myocardial Infarction (NSTEMI)， introducing a number of recommendations for initial diagnostic tests， choice and duration of antiplatelet therapy， and new anticoagulants. The new document also highlights strategies and agents that are no longer considered valuable in the treatment or diagnosis of patients with unstable coronary artery disease (CAD)， such as hormone replacement therapy， vitamins and other anti-oxidants.

ACS Guidelines 2007:  Highlights on Risk Stratification and Overall recommendations.

When compared to the 2002 Guidelines， the update has tempered the emphasis on an initial invasive strategy for all UA/NSTEMI – Acute Coronary Syndrome (ACS) - patients. The 2007 update， making an emphasis on risk stratification (combining clinical variable， biomarkers， imaging) is suggesting  physicians to first establish whether patients are high or low risk and then apply the guidelines according to that initial risk assessment.

For low-risk patients， particularly low-risk women， an initially conservative strategy is considered more appropriate. Low-risk patients would first be noninvasively risk-stratified and treated medically. Considering the very intensive (aggressive) and powerful pharmacologic options (antithrombins， antiplatelets， nitrates， betablockers， statins) and  based on the Invasive Versus Conservative Treatment in Unstable Coronary Syndome (ICTUS) trial， the guidelines also state that an initially conservative strategy can also be considered in stabilized patients.

The guidelines give a 1a recommendation for use of an early invasive strategy in patients who match any of these risk factors， including those who have positive markers， but it would be an acceptable option  — a 2b recommendation — where practitioners can consider a conservative strategy if they initially stabilize the patient.

Other notable changes  in the 2007 update include a fresh emphasis on reducing delays to initial evaluation and facilitated emergency-department (ED) diagnosis and triage， including the use of a 12-lead ECG ideally within 10 minutes of ED arrival.

The 2007 update brings into consideration cardiac imaging， this time as an important adjunct for diagnosis and risk stratification. The use of multislice computed tomographic (CT) angiography and cardiac MRI  is recommended as long as it reflects other recent appropriateness criteria and scientific statements dealing with imaging.

Although the 2002 guidelines recommended an early invasive strategy (diagnostic angiography and revascularization) for UA/NSTEMI， the current guidelines differentiate between high- and low-risk patients with UA/NSTEMI. Risk scores are used to determine risk status. Use of troponin biomarkers as markers of cardiac damage and of BNP markers for assessment of cardiac risk may be useful in risk stratification when integrated into an overall clinical risk score.

Brain-type natriuretic peptide (BNP) has been added to the guidelines as a biomarker test that can be considered to supplement global risk assessment in ACS patients (TACTICS TIMI 18). Cardiac-specific troponin is recommended as the "preferred marker."

For unstable and high-risk patients， an early invasive strategy is recommended to establish and maintain normal levels of myocardial perfusion by mechanical means. Evidence favors an early intervention at intervals of less than 6 to 24 hours， rather than at intervals of 48 to 96 hours.

However， stabilized patients with UA/NSTEMI and those at low risk may be treated conservatively at first with a noninvasive stress test， echocardiogram， or radionuclide angiogram. Although PCI is beneficial in high-risk patients， it actually worsens the risk in low-risk women. The success of antiplatelet and anticoagulant therapies also depends in part on disease risk.

During hospitalization for UA/NSTEMI， all patients should refrain from use of NSAIDs. Hormone replacement therapy should be discontinued in postmenopausal women.

On the use of Antiplatelet therapy:

For patients treated invasively， the recommended duration of clopidogrel therapy has been extended for at least one year after drug-eluting stent placement (December 2006 position paper) and ideally up to one year with a bare-metal stent (CURE-PCI) or even with medical therapy (CURE)，

The new guidelines incorporate a higher loading dose of clopidogrel.  Based on recent studies using different loading doses of 300， 600 or 900 mg， it was identified that a 600 mg loading dose offered a more prompt and reliable platelet inhibition than a 300 mg loading. There was no incremental benefit of increasing the dose to 900 mg. (Kastrati， ISAR-CHOICE， ARMYDA). More studies will be required in order to determine the impact of this higher dose on outcomes. Recent data from the ARMYDA investigators (TCT 2007) does not show any incremental benefit of the 600 mg loading dose if the patient is already on chronic Clopidogrel treatment prior to PCI. A 300 mg loading dose prior to PCI would suffice in those cases.

ASA should be administered to patients with ACS as soon as possible (unless contraindicated) and continued lifelong. Patients with ASA allergy or intolerance should be treated with clopidogrel.

Clopidogrel， in addition to ASA， should be initiated in patients in whom either a conservative or an early invasive therapy is considered， but the likelihood of surgical disease requiring early coronary artery bypass grafting (CABG) is low.

Antiplatelet therapy with clopidogrel 75 mg/day should be given for 1 year or more after receiving a drug-eluting stent. Treatment should include aspirin (162 - 325 mg/day) for 3 months or more after implantation of a sirolimus-eluting stent and for 6 months after implantation of a paclitaxel-eluting stent， then continued indefinitely at 75 to 162 mg/day.

Patients with UA/NSTEMI who are treated medically without stenting should receive aspirin (75 - 162 mg/day) indefinitely and clopidogrel (75 mg/day) for 1 to 12 months. Patients with UA/NSTEMI who are treated with bare-metal stents should receive aspirin (162 - 325 mg/day) for at least 1 month， then indefinitely at 75 to 162 mg/day， and clopidogrel 75 m