Chapter 17. Chest Pain: Cardiac or Not

Patients with acute nontraumatic chest pain are among the most challenging patients cared for by emergency physicians. They may appear seriously ill or completely well and yet remain at significant risk for sudden death or an acute myocardial infarction (AMI).

The typical pain of myocardial ischemia has been described as retrosternal or epigastric squeezing, tightening, crushing, or pressure-like discomfort. The pain may radiate to the left shoulder, jaw, arm, or hand. In many cases, particularly in the elderly, the chief complaint is not chest pain, but of a poorly described visceral sensation with associated dyspnea, diaphoresis, nausea, light-headedness, or profound weakness. The onset of symptoms may be sudden or gradual, and symptoms usually last minutes to hours. In general, symptoms that last less than 2 min or are constant over days are less likely to be ischemic in origin. Symptoms that are new or familiar to the patient but now occur with increasing frequency, severity, or at rest are called unstable and warrant urgent evaluation even if they are absent at the time of presentation. Cardiac risk factors should be used only to predict coronary artery disease within a given population and not in an individual patient. Women, diabetics, the elderly, and patients with psychiatric disorders may have more atypical symptoms of ischemia. Although some symptoms such as radiation of pain to the arms, an exertional component, associated diaphoresis, nausea and vomiting increase the likelihood that a patient is suffering from an AMI; there is no identifiable symptom complex that allows for a definitive diagnosis of the AMI patient without objective testing.

Patients with acute myocardial ischemia may appear clinically well or be profoundly hemodynamically unstable. The degree of hemodynamic instability is dependent on the amount of myocardium at risk, associated dysrhythmias, or preexisting valvular or myocardial dysfunction. Worrisome signs may be clinically subtle, particularly the presence of sinus tachycardia, which may be due to pain and fear or may be an early sign of physiologic compensation for left ventricular failure. Patients with acute ischemia often have a paucity of significant physical findings. Rales, a third or fourth heart sound, cardiac murmurs, or rub are clinically relevant and important findings. The presence of chest wall tenderness has been demonstrated in 5% to 10% of patients with AMI, so its presence should not be used to exclude the possibility of acute myocardial ischemia. Also, response to a particular treatment such as nitroglycerin or a “gastrointestinal (GI) cocktail” should not be taken as evidence of a certain disease.

Electrocardiography

Of all the diagnostic tools clinically used in assessing chest pain, the electro-cardiogram (ECG) is the most reliable when used and interpreted correctly. Patients with acute infarctions may have ECG findings that range from acute ST-segment elevations to completely normal. This range means that the ECG is useful only when it has a positive, or diagnostic, finding. New ST-segment elevations, Q waves, bundle branch block, and T-wave inversions or normalizations are strongly suggestive of ischemia and warrant aggressive management in the emergency department (ED). The presence of a normal or unchanged ECG does not rule out the diagnosis of acute myocardial ischemia.

Serum Markers

Serum markers, if positive, are highly specific for AMI. Creatinine kinase and its MB isoenzyme constitute the historical gold standard for diagnosing AMI, but have been replaced by troponin as the standard for the diagnosis of AMI. Cardiac-specific troponin I and T are not found in skeletal muscle, and have a much greater sensitivity and specificity for AMI. Other clinical conditions such as aortic dissection, acute CHF, aortic valve disease, and some arrhythmias can be associated with an elevated troponin in the absence of ischemic heart disease. However, the documentation of normal serum markers in the bloodstream does not exclude the diagnosis of AMI. These enzymes will not become elevated in serious disease conditions such as unstable angina. The use of these markers can aid the clinician in assessing risk for patients with chest pain, including disposition within the hospital. A serial enzyme evaluation can be used to appropriately risk stratify individual patients (Fig. 17-1).

Echocardiography

Emergency 2-dimensional echocardiography may have value in the evaluation of chest pain when the ECG is nondiagnostic, eg, in patients with pacemakers, have a bundle branch block, or have an abnormal ECG at baseline. The finding of regional wall motion abnormalities in the acutely symptomatic patient is strongly suggestive of active ischemia. Wall motion abnormality also may represent previous myocardial injury. Two-dimensional echocardiography also may aid in the diagnosis of other conditions that may mimic ischemic disease, such as pericarditis, aortic dissection, or hypertrophic cardiomyopathy.

Provocative Tests

Many tests currently being performed in some EDs will unmask otherwise unrecognized but clinically significant ischemic disease. Patients with atypical chest pain and a normal stress thallium or technetium scan have a very low incidence of short- and long-term subsequent ischemic events. Thallium or sestamibi testing can be done in the ED to further risk stratify patients in the hospital and perhaps be used in consideration for patient discharge from the ED.

The priority must always be to exclude life-threatening conditions, and the ED physicians should organize their test-ordering strategies to screen for those conditions first. (Table 17-1 lists possible causes of nontraumatic chest pain.)

Differential Diagnosis

What follows is list of common etiologies of chest pain that should be considered by the emergency physician (Table 17-1).

Angina Pectoris

The typical pain of chronic stable angina is episodic and lasts 5 to 15 min. It is precipitated by exertion and relieved with rest or sublingual nitroglycerin within 3 min. The pain is typically visceral in nature (aching, pressure, and squeezing), with radiation to the neck, jaw, arm, or hand. In individual patients the character of each attack varies little with recurrent episodes. Most patients can differentiate their usual angina from other causes of pain. Physicians evaluating patients with stable angina should screen carefully for changes in the pattern that would suggest a shift from stable to unstable angina or even suggest a different diagnosis.

Unstable Angina

Patients who complain of recent onset of angina, changes in the character of the angina, or angina at rest are thought to have an unstable pattern of their angina. They are at risk for an AMI or sudden cardiac death (see Chapter 18 for management).

Variant (Prinzmetal) Angina

This form of angina is thought to be due to spasm of the epicardial vessels in patients with normal coronary arteries (one-third of cases) or in patients with underlying atherosclerotic disease (two-thirds of cases). Pain typically occurs at rest and may be precipitated by the use of tobacco or cocaine. The ECG typically shows ST-segment elevations during an acute attack.

Acute Myocardial Infarction

Ischemic pain that lasts longer than 15 min, is not relieved by nitroglycerin, or is accompanied by diaphoresis, dyspnea, nausea, or vomiting suggests the diagnosis of AMI. The clinician must understand the limitations of the screening tools used in the ED and should have a high level of suspicion for AMI in patients with risk factors and prolonged or persistent symptoms for which there is no other clear diagnosis (see Chapter 18).

Aortic Dissection

This diagnosis should be suspected in the patient who complains of sudden onset of severe, tearing pain in the retrosternal or midscapular area. High-risk patients are also those at risk for AMI, specifically the middle-age hypertensive male. The patient may be hypertensive or hypotensive in shock. There may be a diastolic murmur of aortic regurgitation, indicating a proximal dissection, or distal pulse deficits, indicating a distal dissection. The dissection may occlude coronary ostia, resulting in myocardial infarction, or the carotids, resulting in cerebral ischemia and stroke. Chest x-ray, computed tomography, transesophageal echocardiography (TEE), and angiography can aid in the diagnosis of this condition (see Chapter 27 for a complete discussion of aortic dissection).

Pericarditis

The patient with pericarditis typically will complain of pain that is constant, retrosternal, and radiating to the back, neck, or jaw. Pain is classically worsened by lying supine and is relieved by sitting forward. The presence of a pericardial friction rub supports the diagnosis. ECG may show PR-segment depressions, diffuse ST-segment elevations, or T-wave inversions that are typically diffuse (see Chapter 24 for a complete discussion of pericarditis).

Acute Pericardial Tamponade

Patients with acute tamponade may complain of positional or pleuritic chest pain, dyspnea, and palpitations. Physical examination will show tachycardia, hypotension, jugular venous distention, and distant heart sounds. If cardiovascular collapse is imminent, emergent pericardiocentesis is indicated.

Pulmonary Embolus

Patients typically complain of sudden onset of pleuritic chest pain associated with dyspnea, tachypnea, tachycardia, or hypoxemia. The absence of any of these findings does not preclude the diagnosis, and a high index of suspicion is essential (see Chapter 25 for a complete discussion of pulmonary embolism).

Musculoskeletal Causes

Chest pain due to irritation or inflammation of structures in the chest wall is commonly seen in the ED. Possible causes include costochondritis, intercostal strain due to severe coughing, and pectoralis muscle strain in the setting of recent physical exertion. Patients will complain of sharp pain that is worsened with movement of the chest wall (eg, coughing, and some pain that can be elicited by palpation of the chest wall). These findings in patients without any other symptoms and no history of significant cardiac disease support the diagnosis of musculoskeletal pain. This pain is generally responsive to nonsteroidal anti-inflammatory drugs. It is important to emphasize that the presence of chest wall tenderness does not rule out the possibility of myocardial ischemia.

Gastrointestinal Causes

Esophageal reflux, dyspepsia syndromes, and esophageal motility disorders can produce chest pain that is difficult to distinguish from ischemic pain. Patients may complain of burning, gnawing pain associated with an acid taste radiating into the throat. Pain may be exacerbated by meals, worsen when supine, and may be associated with belching. Clinicians should determine whether the symptoms are due to a GI disorder based on the clinical presentation and the absence of findings and/or risk factors suggesting an ischemic cause. Diagnostic decisions should not be made on the basis of a response to a therapeutic trial of antacids, GI cocktails, or nitroglycerin (see Chapters 35, 40, and 41 for more discussion on GI causes of chest pain).

1. It should be assumed that every patient with any risk complaining of chest pain may be having an AMI and should be evaluated for this diagnosis.

2. Patients with suspicious histories should have a large-bore intravenous line established, a cardiac monitor, and supplemental oxygen. Vital signs and pulse oximetry should be monitored continuously.

3. An ECG should be obtained on all patients for whom there is a reasonable suspicion of myocardial ischemia.

4. Aspirin should be given early as other testing is being accomplished in patients considered at risk for AMI (see Chapter 18 for details and additional medications).

5. If the etiology of chest pain remains unclear, clinicians should consider further testing and observation/admission as guided by clinical suspicion and findings.