Is a chest x-ray (CXR) a suitable initial imaging test for evaluating chest pain in a patient with potential pulmonary or cardiac conditions, such as chronic obstructive pulmonary disease (COPD) or coronary artery disease (CAD)?

Chest X-Ray for Evaluating Chest Pain

Chest X-ray should be considered for patients with chest pain when there are signs or symptoms of heart failure, suspected acute pulmonary disease, or suspected non-coronary thoracic causes of chest pain, but it does not provide specific diagnostic or risk stratification information for coronary artery disease itself. 1

Role of Chest X-Ray in Chronic Coronary Syndromes

Chest X-ray has limited utility for diagnosing or risk-stratifying coronary artery disease (CAD). The 2024 European Society of Cardiology guidelines explicitly state that in the context of chronic coronary syndromes, chest X-ray "does not yield specific information for accurate diagnosis or risk stratification" of CAD. 1 However, it serves important ancillary functions:

• Heart failure assessment: Chest X-ray should be considered (Class IIa, Level C) when signs and symptoms suggest heart failure, as it can identify pulmonary edema or cardiomegaly. 1

• Pulmonary comorbidities: It helps diagnose pulmonary conditions that frequently coexist with CAD, such as COPD, pneumonia, or pleural effusions. 1

• Alternative diagnoses: Chest X-ray can rule out other causes of chest pain including pneumothorax, rib fractures, aortic pathology (though with lower sensitivity than CT), or mediastinal masses. 1

Appropriate Imaging for CAD Evaluation

For actual CAD diagnosis and risk stratification, coronary CT angiography (CCTA) is the preferred initial test for patients with low to moderate (>5%-50%) pre-test likelihood of obstructive CAD. 2 Functional imaging (SPECT, PET, stress CMR, or stress echocardiography) is recommended for moderate to high risk patients (>15%-85% pre-test likelihood). 2

The key distinction is that chest X-ray addresses complications and alternative diagnoses, while CCTA or functional imaging addresses the coronary disease itself. 1, 2

Clinical Decision Algorithm

When evaluating chest pain, follow this structured approach:

1. Clinical assessment first: Determine pre-test probability of CAD based on age, sex, type of chest pain, and risk factors. 1

2. Obtain chest X-ray if:

   • Signs of heart failure present (dyspnea, orthopnea, peripheral edema, elevated JVP) 1
   • Suspected acute pulmonary disease (fever, productive cough, hypoxia) 1
   • Suspected non-coronary thoracic pathology (sudden severe pain suggesting dissection, pleuritic pain suggesting pneumothorax or PE) 1

3. Proceed to definitive CAD imaging:

   • CCTA for low-moderate risk (5-50% pre-test probability) 2
   • Functional stress testing for moderate-high risk (15-85% pre-test probability) 2

Common Pitfalls and Caveats

Do not rely on chest X-ray alone to exclude significant cardiac pathology. A normal chest X-ray does not rule out acute coronary syndrome, significant CAD, or early heart failure. 1, 3 The sensitivity of chest X-ray for detecting acute myocardial ischemia is essentially zero—it only shows consequences like pulmonary edema in advanced cases. 1

Chest X-ray has significant limitations in acute settings:

• Portable AP radiographs have lower sensitivity for pneumothorax, hemothorax, and lung contusions compared to standard PA/lateral views 3
• Approximately 40% of patients with "normal" chest X-rays may have injuries detected on CT 3
• Chest X-ray misses up to 80% of hemothorax cases and 50% of vertebral/rib fractures compared to CT 3

In patients with persistent chest pain despite negative initial workup, do not repeat chest X-rays—proceed to CCTA or functional imaging based on pre-test probability. 2 The chest X-ray has already served its purpose of excluding gross pulmonary or pleural pathology.

Special Populations

In COPD patients presenting with chest pain, chest X-ray is particularly valuable as it can detect exacerbations, pneumonia, pneumothorax, or lung cancer while also establishing baseline lung architecture. 4 Studies show that 14% of chest X-rays in COPD patients detect potentially treatable dyspnea-causing disease beyond COPD itself. 4

In patients with chronic cough and chest pain, chest X-ray is usually appropriate as initial imaging to exclude structural abnormalities, malignancy, or interstitial lung disease before proceeding with empiric treatment. 1, 5