Chest Pain in the Ambulatory Setting

Background

Chest pain is common, leading to ~4 million outpatient visits/year in the U.S. The lifetime prevalence of chest pain in the U.S. is 20-40%, and women experience chest pain more often than men. Of all ED patients with chest pain, only ~5% have an acute coronary syndrome (ACS), and more than half will ultimately be found to have a noncardiac cause of their pain. Nonetheless, chest pain is the most common symptom of CAD in both men and women.

Guidance

We have many clinical resources at our disposal in evaluating chest pain, including the AHA’s 2021 Guideline for the Evaluation and Diagnosis of Chest Pain that includes the following 10 take-home messages for evaluation and diagnosis:

  1. Chest Pain Means More Than Pain in the Chest. Pain, pressure, tightness, or discomfort in the chest, shoulders, arms, neck, back, upper abdomen, or jaw, as well as shortness of breath and fatigue should all be considered anginal equivalents.
  2. High-Sensitivity Troponins Preferred. High-sensitivity cardiac troponins are the preferred standard for establishing a biomarker diagnosis of acute myocardial infarction, allowing for more accurate detection and exclusion of myocardial injury.
  3. Early Care for Acute Symptoms. Patients with acute chest pain or chest pain equivalent symptoms should seek medical care immediately by calling 9-1-1. Although most patients will not have a cardiac cause, the evaluation of all patients should focus on the early identification or exclusion of life-threatening causes.
  4. Share the Decision-Making. Clinically stable patients presenting with chest pain should be included in decision-making; information about risk of adverse events, radiation exposure, costs, and alternative options should be provided to facilitate the discussion.
  5. Testing Not Needed Routinely for Low-Risk Patients. For patients with acute or stable chest pain determined to be low risk, urgent diagnostic testing for suspected coronary artery disease is not needed.
  6. Pathways. Clinical decision pathways for chest pain in the emergency department and outpatient settings should be used routinely.
  7. Accompanying Symptoms. Chest pain is the dominant and most frequent symptom for both men and women ultimately diagnosed with acute coronary syndrome. Women may be more likely to present with accompanying symptoms such as nausea and shortness of breath.
  8. Identify Patients Most Likely to Benefit From Further Testing. Patients with acute or stable chest pain who are at intermediate risk or intermediate to high pre-test risk of obstructive coronary artery disease, respectively, will benefit the most from cardiac imaging and testing.
  9. Noncardiac Is In. Atypical Is Out. “Noncardiac” should be used if heart disease is not suspected. “Atypical” is a misleading descriptor of chest pain, and its use is discouraged.
  10. Structured Risk Assessment Should Be Used. For patients presenting with acute or stable chest pain, risk for coronary artery disease and adverse events should be estimated using evi- dence-based diagnostic protocols.

Initial Evaluation

The initial evaluation of patients with chest pain requires a focused history, exam, and diagnostic testing. Selected guideline recommendations on history and exam include the following (all of which are strong recommendations):

  • In patients with chest pain, a focused history that includes characteristics and duration of symptoms relative to presentation as well as associated features, and cardiovascular risk factor assessment should be obtained.
  • Women who present with chest pain are at risk for underdiagnosis, and potential cardiac causes should always be considered.
  • In patients with chest pain who are >75 years of age, ACS should be considered when accompanying symptoms such as shortness of breath, syncope, or acute delirium are present, or when an unexplained fall has occurred.
  • In patients presenting with chest pain, a focused cardiovascular examination should be performed initially to aid in the diagnosis of ACS or other potentially serious causes of chest pain (eg, aortic dissection, PE, or esophageal rupture) and to identify complications.
  • Cultural competency training is recommended to help achieve the best outcomes in patients of diverse racial and ethnic backgrounds who present with chest pain.

Patients use a variety of terms in describing chest pain, some of which are associated with a higher likelihood of ischemia:

Source: Gulati et al. Circulation. 2021

There are also a number of symptoms considered to be anginal equivalents, including pain, pressure, tightness, or discomfort in the chest, shoulders, arms, neck, back, upper abdomen, or jaw, as well as shortness of breath, belching, nausea, indigestion, diaphoresis, dizziness, lightheadedness, clamminess, and fatigue.

  • Interestingly, there is frequently a lack of correlation between intensity of symptoms and seriousness of disease and general similarity of symptoms among different causes of chest pain.
  • Relief with nitroglycerin is not necessarily diagnostic of myocardial ischemia and should not be used as a diagnostic criterion, especially because other entities demonstrate comparable response (eg, esophageal spasm).
  • There are significant racial and ethnic disparities when triaging patients who present for the evaluation of chest pain. For instance, despite a greater number of Black patients presenting with angina relative to other races, this population is less likely to be treated urgently and less likely to have an ECG performed, samples for cardiac biomarkers drawn, cardiac monitoring performed, or pulse oximetry measured.

Selected guideline recommendations for diagnostic testing include the following (all of which are strong recommendations):

  • Unless a noncardiac cause is evident, an ECG should be performed for patients seen in the office setting with stable chest pain; if an ECG is unavailable the patient should be referred to the ED so one can be obtained.
  • Patients with clinical evidence of ACS or other life-threatening causes of acute chest pain seen in the office setting should be transported urgently to the ED, ideally by EMS.
  • In all patients who present with acute chest pain regardless of the setting, an ECG should be acquired and reviewed for STEMI within 10 minutes of arrival.
  • In all patients presenting to the ED with acute chest pain and suspected ACS, cTn should be measured as soon as possible after presentation.
  • In patients presenting with acute chest pain, serial cTn I or T levels are useful to identify abnormal values and a rising or falling pattern indicative of acute myocardial injury.
  • In patients presenting with acute chest pain, high-sensitivity cTn is the preferred biomarker because it enables more rapid detection or exclusion of myocardial injury and increases diagnostic accuracy.
  • With availability of cTn, creatine kinase myocardial (CK-MB) isoenzyme and myoglobin are not useful for diagnosis of acute myocardial injury.

Word Soup

We use (and confuse) several terms when referring to myocardial injury vs ischemia vs infarction. JACC’s 2018 Fourth Universal Definition of Myocardial Infarction provides some clarity:

Source: Thygesen et al. J Am Coll Cardiol. 2018

In short, the clinical definition of myocardial infarction (MI) denotes the presence of acute myocardial injury detected by abnormal cardiac biomarkers in the setting of evidence of acute myocardial ischemia.

Myocardial ischemia in a clinical setting can most often be identified from the patient’s history and from the ECG. Possible (but non-specific) ischemic symptoms include various combinations of chest, upper extremity, mandibular, or epigastric discomfort during exertion or at rest, or an ischemic equivalent such as dyspnea or fatigue.

If myocardial ischemia is present clinically or detected by ECG changes together with myocardial injury, manifested by a rising and/or falling pattern of cTn values, a diagnosis of acute MI is appropriate. If there is no evidence to support the presence of myocardial ischemia, a diagnosis of myocardial injury should be made.

Source: Thygesen et al. J Am Coll Cardiol. 2018

Other key definitions:

  • Angina: Chest pain as a symptom of ischemia
    • Stable angina: Reproducible angina of at least 2 months’ duration that is precipitated by a consistent level of exertion or emotional stress, is relieved with rest
    • Unstable angina: New-onset angina or angina occurring at a relatively low level of exertion, occurring at rest, or accelerating in frequency or severity, in the presence of normal cardiac biomarkers
  • STEMI: MI with ST-segment elevation of ≥1 mm in ≥2 contiguous limb or chest leads
    • Although ST-segment elevation in leads V2 and V3 must be ≥2 mm in men and ≥1.5 mm in women, ST-elevation equivalents include new LBBB or posterior MI (tall R waves and ST depressions in V1-V4)
  • NSTEMI: MI with positive cardiac biomarkers but without ST elevations or ST-elevation equivalents; may have nonspecific ECG changes, ST-segment depression, and T-wave inversion

Blog post based on Med-Peds Forum talk by Rebecca Raymond-Kolker, PGY3

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