Chapter 013. Chest Discomfort (Part 6)

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Acute Chest Discomfort In patients with acute chest discomfort, the clinician must first assess the patient's respiratory and hemodynamic status. If either is compromised, initial management should focus on stabilizing the patient before the diagnostic evaluation is pursued. If, however, the patient does not require emergent interventions, then a focused history, physical examination, and laboratory evaluation should be performed to assess the patient's risk of life-threatening conditions. Clinicians who are seeing patients in the office setting should not assume that they do not have acute ischemic heart disease, even if the prevalence may be lower. Malpractice litigation related to myocardial infarctions...

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Chapter 013. Chest Discomfort (Part 6) Acute Chest Discomfort In patients with acute chest discomfort, the clinician must first assess the patient's respiratory and hemodynamic status. If either is compromised, initial management should focus on stabilizing the patient before the diagnostic evaluation is pursued. If, however, the patient does not require emergent interventions, then a focused history, physical examination, and laboratory evaluation should be performed to assess the patient's risk of life-threatening conditions. Clinicians who are seeing patients in the office setting should not assume that they do not have acute ischemic heart disease, even if the prevalence may be lower. Malpractice litigation related to myocardial infarctions that were missed during office evaluations is becoming increasingly common, and ECGs were not
performed in many such cases. The prevalence of high-risk patients seen in office settings may be increasing due to congestion in emergency departments. In either setting, the history should include questions about the quality and location of the chest discomfort (Table 13-2). The patient should also be asked about the nature of onset of the pain and its duration. Myocardial ischemia is usually associated with a gradual intensification of symptoms over a period of minutes. Pain that is fleeting or that lasts hours without being associated with electrocardiographic changes is not likely to be ischemic in origin. Although the presence of risk factors for coronary artery disease may heighten concern for this diagnosis, the absence of such risk factors does not lower the risk for myocardial ischemia enough to be used to justify a decision to discharge a patient. Wide radiation of chest pain increases probability that pain is due to myocardial infarction. Radiation of chest pain to the left arm is common with acute ischemic heart disease, but radiation to the right arm is also highly consistent with this diagnosis. Figure 13-1 shows estimates derived from several studies of the impact of various clinical features from the history on the probability that a patient has an acute myocardial infarction. Figure 13-1
Impact of chest pain characteristics on odds of acute myocardial infarction (AMI). (Figure prepared from data in Swap and Nagurney.) Right shoulder pain is also common with acute cholecystitis, but this syndrome is usually accompanied by pain that is located in the abdomen rather than chest. Chest pain that radiates between the scapulae raises the question of aortic dissection. The physical examination should include evaluation of blood pressure in both arms and of pulses in both legs. Poor perfusion of a limb may be due to an aortic dissection that has compromised flow to an artery branching from the aorta. Chest auscultation may reveal diminished breath sounds; a pleural rub; or evidence of pneumothorax, pulmonary embolism, pneumonia, or pleurisy. Tension pneumothorax may lead to a shift in the trachea from the midline, away from the side of the pneumothorax. The cardiac examination should seek pericardial rubs,
systolic and diastolic murmurs, and third or fourth heart sounds. Pressure on the chest wall may reproduce symptoms in patients with musculoskeletal causes of chest pain; it is important that the clinician ask the patient if the chest pain syndrome is being completely reproduced before drawing too much reassurance that more serious underlying conditions are not present. An ECG is an essential test for adults with chest discomfort that is not due to an obvious traumatic cause. In such patients, the presence of electrocardiographic changes consistent with ischemia or infarction (Chap. 221) is associated with high risks of acute myocardial infarction or unstable angina (Table 13-4); such patients should be admitted to a unit with electrocardiographic monitoring and the capacity to respond to a cardiac arrest. The absence of such changes does not exclude acute ischemic heart disease, but the risk of life- threatening complications is low for patients with normal electrocardiograms or only nonspecific ST-T-wave changes. If these patients are not considered appropriate for immediate discharge, they are often candidates for early or immediate exercise testing. Finding Prevalence Myocardial Unstable
Infarction, % Angina, % ST elevation ( 1 mm) or Q waves 79 12 on ECG not known to be old Ischemia or strain on ECG not 20 41 known to be old (ST depression 1 mm or ischemic T waves) None of the preceding ECG 4 51 changes but a prior history of angina or myocardial infarction (history of heart attack or nitroglycerin use) None of the preceding ECG 2 14 changes and no prior history of angina or myocardial infarction (history of heart attack or nitroglycerin use) Note: ECG, electrocardiogram.