Focus On The Management Of Acute Coronary Syndrome: What's Now And What's To Come
Robert B. Parker, PharmD
Coronary heart disease is the number 1 cause of death in the United States.1 Many patients will present to the hospital with an acute coronary syndrome (ACS) regardless of their history of symptomatic heart disease. Patients with ACS are at significant risk of death and subsequent cardiovascular (CV) events. However, immediate assessment of clinical risk upon presentation followed by appropriate treatment reduces the risk of a poor outcome.
The prevalence of risk factors for cardiovascular disease (CVD) is high in developed and developing countries, which ensures that many patients will suffer from ACS. In the United States, the prevalence of risk factors is influenced by cultural differences, among numerous other factors, and is inversely proportional to economic and education levels. Therefore, many patients who are at the greatest risk for CV events are also those who face the greatest barriers to appropriate care.
ACS is an umbrella term used to describe any group of symptoms of acute myocardial ischemia (ie, chest pain caused by insufficient blood supply to the heart muscle) that is usually caused by atherosclerotic coronary artery disease. Upon presentation, patients with symptoms of ACS are initially stratified by the results of a 12-lead electrocardiogram (ECG) as having ST-segment elevation myocardial infarction (STEMI), non-ST-segment elevation myocardial infarction (NSTEMI), or unstable angina (UA). UA is a condition that is closely related to NSTEMI and may show similar results on the initial ECG. UA is the relatively high-risk middle ground between stable angina and myocardial infarction, and can usually only be distinguished by the presence (NSTEMI) or absence (UA) in the bloodstream of biomarkers of myocardial injury such as troponin.2 Although STEMI, NSTEMI, and UA are 3 distinct disorders, they share a common pathophysiologic origin characterized by disruption or rupture of a vulnerable atherosclerotic plaque and subsequent thrombus formation and vessel occlusion.
The treatment goals for patients with NSTEMI/UA are the relief of ischemia and prevention of subsequent CV events. Evidence-based treatment strategies for these patients include pharmacologic interventions, such as anti-ischemic, antiplatelet, and antithrombotic agents; and invasive interventions, such as percutaneous coronary intervention and coronary artery bypass graft surgery. Invasive interventions are generally reserved for high-risk patients or patients who do not respond to pharmacologic intervention. Low-risk patients may benefit from assessments that determine their need for coronary angiography or revascularization. Patient preference for treatment approach may also inform the choice of intervention in this group.2
In this issue of University of Tennessee Advanced Studies in Pharmacy, Kurt C. Kleinschmidt, MD, FACEP, explains the epidemiology and pathophysiology of ACS, including the current prevalence estimates of heart disease among Americans and the impact of heart disease on healthcare costs, morbidity, and mortality rates. Dr Kleinschmidt also reviews the current estimates for the prevalence of CVD risk factors among Americans and the impact these factors may have on the future incidence of ACS. Because inflammation is implicated in all stages of heart disease, Dr Kleinschmidt discusses the proposed role of inflammation in atherosclerotic plaque formation, plaque progression, and thrombus formation. He also reviews the studies that have assessed the use of guideline-recommended therapies in patients with ACS.
Edith A. Nutescu, PharmD, discusses the necessary assessments for diagnosing ACS and determining patient risk level. Her review of clinical evaluation strategies covers American College of Cardiology/ American Heart Association (ACC/AHA) defined characteristics for patients at high, moderate, or low risk for death or CV events upon presentation, including diagnostic ECG morphology and diagnostic serum cardiac markers. Dr Nutescu's review of risk stratification includes a discussion of the TIMI (Thrombolysis in Myocardial Infarction) risk score and ACC/AHA recommended assessments for early risk stratification. Dr Nutescu also discusses immediate patient management strategies for patients at various levels of risk.
In her article, M. Dominique Ashen, PhD, CRNP, highlights current and emerging treatment strategies for patients with ACS. She explains ACC/AHA guideline-recommended pharmacologic interventions and invasive interventions, including anti-ischemic agents, antiplatelet agents, anticoagulants, percutaneous coronary intervention, and coronary artery bypass graft surgery. Among her discussion of emerging treatment strategies are the clinical implications of recent studies in patients with ACS. She reviews the results of pharmacologic interventions in primary prevention and secondary prevention in addition to pharmacologic treatments in conjunction with invasive intervention. Dr Ashen summarizes her review of emerging treatment strategies with a discussion of the potential clinical impact of recent trial results.
In closing, I present a case study that reviews the clinical presentation and treatment course for a 64-year-old male patient with ACS. The patient had a history of myocardial infarction and symptomatic coronary artery disease.
Strikingly, the case history illustrates the devastating impact of a single risk factor on the emergence and progression of coronary artery disease. It also highlights this patient's need for more aggressive secondary preventive therapy following his second myocardial infarction.
This issue of University of Tennessee Advanced Studies in Pharmacy will underscore the importance of early detection and early treatment strategies for those at risk for ACS. By providing education about appropriate recognition, risk stratification, and prompt acute treatment intervention, it is hoped that there will be improved clinical survival and long-term functional benefits for patients with ACS.
1. Thom T, Haase N, Rosamond W, et al. Heart disease and stroke statistics—2006 update. A report from the American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Circulation. 2006;113(6):Assessed March 25, 2006. 85-151.
2. Braunwald E, Antman E, Beasley J, et al. ACC/AHA 2002 guideline update for the management of patients with unstable angina and non-ST-segment elevation myocardial infarction. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Available at: http://www.acc.org/clinical/guidelines/unstable/unstable.pdf. Accessed March 25, 2006.
The content in this monograph was developed with the assistance of a staff medical writer. Each author had final approval of his/her article and all its contents.
*Associate Professor, Department of Pharmacy, University of Tennessee, Memphis, Tennessee.
Address correspondence to: Robert B. Parker, PharmD, Associate Professor, Department of Pharmacy, University of Tennessee, 26 South Dunlap Street, Memphis, TN 38136. E-mail: email@example.com.