Cardiology: Unstable Angina/Non-STEMI Management Guidelines Updated

By Robert Fay

The American Heart Association (AHA) and the American College of Cardiology (ACC) recently published a focused update to the 2007 guidelines for the management of patients with unstable angina (UA) and non-ST-elevation myocardial infarction (NSTEMI). The writing committee based the update on a review of late-breaking clinical trial results presented in 2008 and 2009 at the ACC, AHA, and European Society of Cardiology meetings, as well as on select data presented through April 2010.

The update alters recommendations regarding dual antiplatelet therapy, including the addition of prasugrel (Effient) as an alternative to clopidogrel (Plavix). The writing committee based its recommendation on the TRITON-TIMI 38 trial, which compared prasugrel with clopidogrel in patients with moderate- to high-risk acute coronary syndrome (ACS) who were referred for percutaneous coronary intervention (PCI). TRITON-TIMI 38 showed prasugrel to be superior to clopidogrel on the primary efficacy endpoint, a composite of cardiovascular death, MI, and stroke, but also showed it to increase bleeding risk. Use of prasugrel as an alternative to clopidogrel should closely follow the trial design.

The writing committee recommended selective use of glycoprotein IIb/IIIa inhibitors (GPIs) as part of triple antiplatelet therapy. However, the use of GPIs as part of triple antiplatelet therapy may “not be supported when there is a concern for increased bleeding risk or in non-high-risk subsets such as those with a normal baseline troponin level, those without diabetes, and those at least 75 years of age, in whom the potential benefit may be significantly offset by the potential risk of bleeding."

The timing of acute interventional therapy has been clarified based on several recent trials. The authors find it reasonable to opt for an early invasive strategy (within 24 hours) for high-risk patients with UA/NSTEMI (defined by a GRACE score of more than 140) after initial stabilization. A more delayed approach is appropriate for low- to intermediate-risk patients.

The authors addressed the role and potential benefit of invasive therapies for patients with advanced renal dysfunction. The committee found that an early invasive strategy (diagnostic angiography with intent to perform revascularization) is reasonable in patients with mild and moderate chronic kidney disease.

The update recommendation for the use of insulin to control blood glucose in UA/NSTEMI supports a more moderate target range in keeping with the 2009 focused update to the STEMI and PCI guidelines. Treatment for hyperglycemia greater than 180 mg/dL (while avoiding hypoglycemia) is advised.

Platelet function testing and genetic testing have also been addressed in response to the FDA’s box warning that clopidogrel may be less effective in altering platelet activity in patients with a reduced functioning CYP2C19 gene. Although the committee found insufficient evidence for a definitive recommendation, the group recommended physicians consider testing if it would affect the management strategy.

Clinicians and institutions that provide care to UA/NSTEMI patients should participate in a quality-of-care data registry designed to track and measure outcomes, complications, and adherence to evidence-based processes of care and quality improvement for unstable UA/NSTEMI.

The update was published on March 28, 2011 on the Circulation and Journal of the American College of Cardiology websites.

Source: Wright RS, Anderson JL, Adams CD, et al. 2011. 2011 ACC/AHA focused update of the guidelines for the management of patients with unstable angina/non-ST-elevation myocardial infarction (updating the 2007 guideline). Published on March 28, 2011 on the Circulation website.