Quick Guide: Acute Coronary Syndrome Guideline Update

Acute coronary syndrome (ACS) is an umbrella term that refers to a spectrum of conditions compatible with acute myocardial ischemia and/or infarction due to an abrupt reduction in coronary blood flow. ACS encompasses unstable angina, non–ST-elevation myocardial infarction (NSTEMI), and ST-elevation myocardial infarction (STEMI). Non–ST-elevation acute coronary syndrome (NSTE-ACS) includes unstable angina and NSTEMI. Diagnosis of ACS is based on patient symptoms, electrocardiogram findings, and serum biomarkers. ST-segment elevation is present in STEMI whereas the absence of persistent ST-segment elevation is suggestive of NSTE-ACS (except in patients with true myocardial infarction). Cases of ACS account for significant morbidity and mortality, and the high rate of rehospitalization for ACS patients yields a substantial healthcare cost. According to a recent review, of more than 1 million hospital discharges due to ACS in the United States, approximately 80% were cases of unstable angina or NSTEMI.¹ To optimize outcomes in older adults, clinicians should be aware of the most current guidelines regarding medical management and pharmacotherapy of patients with NSTE-ACS.

ACC/AHA Guideline Recommendations

In September, the American Heart Association (AHA) and the American College of Cardiology (ACC) released the 2014 AHA/ACC Guideline for the Management of Patients With Non–ST-Elevation Acute Coronary Syndromes.² This guideline is a full revision of the 2007 ACC/AHA clinical practice guidelines for managing unstable angina/NSTEMI. Among the recommendations for prescribing the currently available oral antiplatelet agents, there is evidence-based support to differentiate the use of the P2Y₁₂ inhibitors ticagrelor, clopidogrel, and prasugrel for treatment of NSTE-ACS in various clinical situations.

A key change in the revised guideline is that ticagrelor is preferred over clopidogrel in patients who undergo invasive or ischemia-guided strategy, or those who receive a coronary stent. The recommended maintenance dose of aspirin with ticagrelor is 81 mg daily. This recommendation is based on a review of multiple clinical trials, including PLATO (Platelet Inhibition and Patient Outcomes), a multicenter, double-blind, randomized trial that compared ticagrelor to clopidogrel. In PLATO, Wallentin and colleagues³ compared the two antiplatelet therapies for the prevention of major cardiovascular events in 18,624 patients with ACS, with or without ST-segment elevation. At 12 months, the findings demonstrated that treatment with ticagrelor plus aspirin led to a significantly greater reduction in the primary end point—a composite of cardiovascular death, myocardial infarction, or stroke—compared with clopidogrel plus aspirin treatment (9.8% vs 11.7%, respectively) and a lower rate of all-cause mortality (4.5% vs 5.9%, respectively).

The guideline recommendations specific to P2Y₁₂ inhibitors that were categorized as Class I or Class IIa are outlined in the Table (log in above to download PDF). Class of recommendation indicates anticipated magnitude and judged certainty of benefit in proportion to risk, with class I indicating that a treatment should be administered and class IIa indicating that a treatment is reasonable to administer. Level of evidence (LOE) estimates the degree of certainity in the effects of the treatment intervention, with level A indicating that multiple populations were evaluated and data are derived from multiple randomized clinical trials or meta-analyses; level B indicating that study populations are limited and data are derived from a single randomized trial or nonrandomized studies; and level C indicating limited study population and support derived from consensus-based opinion, case studies, or standards of care.

The ACC/AHA noted that these guidelines do not replace clinical judgment, and that application of these guidelines should also take into account the patient’s comorbidities and goals of treatment.

References

1. Kolansky DM. Acute coronary syndromes: morbidity, mortality, and pharmacoeconomic burden. Am J Manag Care. 2009;15:S36-S41.

2. Amsterdam EA, Wenger NK, Brindis RG, et al. 2014 AHA/ACC guideline for the management of patients with non-ST-elevation acute coronary syndromes: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. Published online ahead of print September 23, 2014.

3. Wallentin L, Becker RC, Budal A, et al. Ticagrelor versus clopidogrel in patients with acute coronary syndromes. N Engl J Med. 2009;361(11):1045-1047.

4. Myocardial infarction. In: Beers MH, Berkow R, eds. Merck Manual of Geriatrics. 3rd ed. Whitehouse Station, NJ: Merck Research Laboratories, 2000:858.

5. Angina pectoris. In: Beers MH, Berkow R, eds. Merck Manual of Geriatrics. 3rd ed. Whitehouse Station, NJ: Merck Research Laboratories, 2000:857.