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LEARNING OBJECTIVES

  1. Learn the differential diagnosis of ischemic chest pain and the laboratory tests used in ruling out and ruling in myocardial injury and acute myocardial infarction.

  2. Learn the clinical features of congestive heart failure (CHF) and the laboratory tests useful in ruling in and ruling out CHF and monitoring and risk outcomes assessment of patients with this disorder.

INTRODUCTION

There are many forms of cardiac disease. This chapter briefly covers the role of biomarkers in acute myocardial infarction (AMI) and congestive heart failure (CHF). The large numbers of other cardiac diseases are not discussed in this chapter because of the relatively minor role of diagnostic clinical laboratory tests in these disorders.

ACUTE MYOCARDIAL INFARCTION

Description

The term AMI is defined as an imbalance between myocardial oxygen supply (ischemia) and demand, resulting in injury to and the eventual death of myocytes. AMI should be used when there is evidence of myocardial necrosis in a clinical setting consistent with acute myocardial ischemia. Such necrosis is most often associated with a thrombotic occlusion superimposed on coronary atherosclerosis. It is now apparent that the process of plaque rupture and thrombosis is one of the ways in which coronary atherosclerosis progresses. Total loss of coronary blood flow results in a clinical syndrome associated with an ST-segment elevation MI (STEMI). Partial loss of coronary perfusion, if severe, can lead to necrosis as well, which is generally less severe and is known as non-ST-segment elevation MI (NSTEMI). Both STEMI and NSTEMI are considered type 1 MIs. In instances of myocardial injury with necrosis from a condition other than coronary artery disease (CAD), (e.g., coronary endothelial dysfunction, respiratory failure, hypotension, etc.), this MI is a type 2 MI that is secondary to ischemic imbalance. Other ischemic events of lesser severity without myocardial necrosis are designated as angina, which can range from stable to unstable.

Approximately 90 million (1 in 3) individuals in the United States have some form of heart disease. Seven million have had an MI and roughly 8.7 million have ischemic angina. Cardiovascular disease is responsible for more deaths and more hospitalizations in the United States than any other disease, over 5 million admissions yearly. Coronary heart disease (CHD) causes over one in seven deaths. Deaths that occur acutely result from ventricular arrhythmias or pump dysfunction and CHF with or without cardiogenic shock. The yearly financial burden of cardiovascular disease is in excess of $300 billion for CHD and stroke.

Cardiovascular disease is responsible for more deaths and more hospitalizations in the United States than any other disease, over 5 million admissions yearly. Coronary heart disease (CHD) causes over one in seven deaths.

In many patients with AMI, no precipitating factor can be identified. The clinical history remains of substantial value in establishing a diagnosis. A prodromal history of angina can ...

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