Mortality and morbidity reduction in acute coronary syndromes (ACS) is predicated upon minimizing the time interval between onset of ischemia and provision of treatment.
Chest pain is the main symptom associated with ischemic heart disease. History should include its severity, location, radiation, duration, and quality. In addition, clinicians should ask about onset and duration of symptoms, provocative or palliative activities, and prior evaluations.
Seven major risk factors for coronary artery disease (CAD) have been identified: age, male sex, family history, cigarette smoking, hypertension (HTN), hypercholesterolemia, and diabetes (DM). However, cardiac risk factors are poor predictors of acute myocardial infarction (AMI) in ED patients. One risk factor, cocaine use, is noteworthy. Cocaine is directly myotoxic, accelerates atherosclerosis and CAD, and may cause myocardial infarction (MI) in patients.
Angina pectoris represents cardiac ischemia, a form of ACS. ACS symptoms may include: chest pain or discomfort, nausea, vomiting, diaphoresis, dyspnea, light-headedness, syncope, and palpitations. Reproducible chest wall tenderness is not uncommon. Angina is typically precipitated by exercise, stress, or cold temperature; pain lasts <10 min and is relieved by rest or nitroglycerin (NTG). Unstable angina, an ACS, represents a clinical state between stable angina and AMI. Unstable angina is present when anginal symptoms meet any of the following criteria: (a) new-onset angina (within 2 months); (b) increasing angina (increased frequency or duration, or decreased threshold for symptom occurrence); (c) angina at rest (within one week).
As compared to angina, AMI is usually accompanied by more severe and prolonged chest discomfort. Symptoms tend to be less responsive to nitroglycerin, and associated symptoms (eg, diaphoresis) are more prominent.
Atypical presentations are common. Elderly patients and those with diabetes may have silent (painless) ischemia. Easy fatigability and/or shortness of breath are common ACS presenting symptoms in women and elderly men. Patients with inferior AMI may have abdominal pain, nausea, or vomiting.
Physical exam findings in patients with ACS range from normal to overt distress. The pulse rate, cardiac rhythm and blood pressure should be assessed and addressed. The first and second heart sounds may be diminished with LV dysfunction. An S3 implies myocardial dysfunction and an S4 suggests longstanding hypertension or myocardial dysfunction. A new murmur may signify papillary muscle dysfunction, valve regurgitation, or a ventricular septal defect. Similarly, the presence of rales is associated with LV dysfunction and left-sided CHF. JVD and peripheral edema suggest right heart failure.
The differential diagnosis of cardiac ischemia is particularly broad (see Chapter 17). Entities that should be considered include pericarditis, cardiomyopathies, cardiac valvular disease, pulmonary embolism, pneumonia, pneumothorax, asthma or chronic obstructive pulmonary disease, gastro-intestinal disorders (especially esophageal disease), chest trauma, chest wall disorders, hyperventilation, aortic aneurysm and dissection, and mediastinal disorders.
The diagnosis of ST-elevation myocardial infarction (STEMI) is based upon appropriate ECG changes occurring in a suggestive clinical setting; early treatment and disposition decision-making ...