The acute coronary syndromes are a collection of clinical disease states that represent the progression of one pathophysiologic mechanism along a spectrum of severity, beginning with unstable angina, and moving through non-Q wave MI, Q wave MI, and potentially culminating with sudden cardiac death. The pathophysiologic mechanism responsible for acute coronary syndromes is rupture of a lipid-laden plaque within the coronary artery that causes varying degrees of clot formation and coronary blood flow obstruction. If myocardial necrosis is documented, the patient is diagnosed with acute myocardial infarction. However, if no myocardial necrosis is noted, the patient is diagnosed with unstable angina. 1,2

According to the most recent figures from the American Heart Association, angina pectoris (chest pain) is diagnosed in more than 6 million individuals within the United States alone, and it is responsible for a portion of all deaths reported from coronary heart disease. 3 Unstable angina is perceived to be the most benign of the acute coronary syndromes because of its lower initial mortality rate, and yet it often represents the entry point to a cardiac career for many patients. Although the initial mortality from unstable angina has been reported in the range of 2% to 4% depending on the level of intervention at the time of symptom onset, the risk of progression to acute myocardial infarction has been documented between 5.4% to 10%. 4 In addition, although the risk of death is greatest at the onset of symptoms and tapers off over the course of the next year, this patient group often experiences a high incidence of recurrent ischemic events, presumably because viable myocardium is still at risk for necrosis. 2

Because of the magnitude of the problem and the potential to save millions of lives every year, intense investigations are underway to develop new diagnostic techniques for identification of patients at risk for acute coronary syndromes and to develop effective treatment strategies to prevent death and improve the quality of life for this patient group. In this issue of The Journal of Cardiovascular Nursing (15:1), we have attempted to capture the most recent advances in the diagnosis and management of unstable angina, recognizing that this is an extremely dynamic field of study, and new findings will have likely occurred since the publication of these articles.

The first article in this issue, "The Vulnerable Coronary Plaque," by Schoenhagen et al., summarizes the most current findings surrounding the pathophysiology of acute coronary syndrome. This is a provocative overview that differentiates the actual characteristics of plaques that are prone to sudden rupture and contrasts them with plaques known to be responsible for the stable coronary syndromes. In addition, the article discusses the limitations of current diagnostic techniques and attempts to explain the mismatch between stress testing, angiographic findings, and acute coronary events. Finally, insights into new imaging techniques, such as intravascular ultrasound and MRI, provide further evidence that we are on the cusp of a new era in diagnosis and management of unstable angina.

The next article by Albert summarizes the role of infection and inflammation in the setting of acute coronary syndromes, one of the most exciting new areas of discovery for this patient population. The article highlights the association between infection and the acute coronary syndrome, and it postulates the potential effect of inflammation on the integrity of the fibrous cap covering the lipid-laden plaque. Albert details the most current findings and suggests potential therapeutic implications once this association is more clearly understood.

Although surgical management of coronary artery disease has been one of the mainstays of treatment, we are continuing to advance our understanding of the patient populations most likely to benefit from surgery and refine the techniques available to manage unstable angina. Weber provides a comprehensive overview of the findings, compares medical versus surgical management of coronary artery disease, and highlights specific considerations for high-risk patient groups who undergo coronary artery bypass surgery. In addition, the article reviews advances in conduit options for surgical revascularization and discusses additional techniques that are available including minimally invasive surgery.

The next article by Pradka reviews the role of lipids, with a specific focus on plaque regression and passivation, issues that are central to the effective management of unstable angina. The article examines the role of cholesterol lowering and its relationship to the acute coronary syndromes, attempting to answer the question, "How low do you go?" Key clinical findings are reviewed and the role of statins in patient management discussed with therapeutic guidelines offered.

In addition to lipid-lowering agents, other critical areas that have yielded extraordinary advances in the pharmacologic management of unstable angina include the development of new antiplatelet and antithrombin agents. Shepard provides an overview of the latest drugs studied in clinical trials or that have become the mainstay of therapy for this patient group, including the glycoprotein IIb/IIIa inhibitors, thienopyridines, hirudin, and hirulog. Because of the marked benefit of these agents in managing patients, the article emphasizes that it is critical for all practitioners to become fully aware of the role of these potent agents in the management of the patient with unstable angina and their implications for nursing practice.

The final article in this issue by Frazier examines numerous factors that influence blood pressure-a known risk factor for the development of coronary artery disease-through the application of a Hypertension Risk Model. In addition, the article compares three of the most common methods of blood pressure measurement and highlights useful clinical implications for each practice.

This issue of JCN summarizes only a fraction of the marked advances that are occurring in the management of the patient with unstable angina. As our ability to detect and treat acute coronary syndromes continues to progress, nursing continues to represent the critical link between technologic advances and management of the patient as a whole. I would encourage all practitioners to attempt to keep pace with the rapidly changing medical practice standards and to identify new avenues for nursing to make a difference.

- Ellen Strauss McErlean, MSN, RN, CCRN

Project Manager; Cardiology Research; The Cleveland Clinic Foundation; Cleveland, Ohio

Issue Editor

REFERENCES