Is a chest X-ray (CXR) helpful in a patient with ST-elevation myocardial infarction (STEMI) and chest pain?

Chest X-Ray in STEMI: Obtain It, But Never Delay Reperfusion

Yes, a portable chest X-ray should be obtained in STEMI patients, but it must never delay reperfusion therapy unless aortic dissection is suspected as a contraindication to treatment. 1

Primary Recommendation

The ACC/AHA guidelines explicitly state that patients with STEMI should have a portable chest X-ray, but this should not delay implementation of reperfusion therapy (Class I recommendation). 1 The only exception is when a potential contraindication such as aortic dissection is suspected, in which case imaging becomes essential to differentiate STEMI from dissection before administering reperfusion therapy. 1

Clinical Utility of CXR in STEMI

The chest X-ray serves several important diagnostic purposes in STEMI patients:

• Identifies alternative diagnoses that can mimic or coexist with STEMI, including aortic dissection, pulmonary embolism, pneumothorax, and pneumonia 1, 2

• Detects complications such as pulmonary edema, cardiogenic shock, or mechanical complications of MI 1

• Guides oxygen therapy decisions by revealing pulmonary congestion that would benefit from supplemental oxygen, though oxygen should only be administered if SaO2 is <90% 1, 3

Critical Timing Algorithm

The workflow should proceed as follows:

1. ECG obtained within 10 minutes of presentation showing ST-elevation 4, 3

2. Immediate activation of reperfusion pathway (primary PCI within 90-120 minutes or fibrinolysis if PCI unavailable) 1, 3

3. Portable CXR ordered simultaneously but performed while reperfusion preparations continue 1

4. CXR reviewed only if it becomes available before catheterization - otherwise review post-procedure 1

When CXR Changes Management

The chest X-ray becomes decision-critical only in specific scenarios:

• Suspected aortic dissection: If clinical features suggest dissection (tearing/ripping pain radiating to back, pulse differential, mediastinal widening), then high-quality portable CXR, echocardiography, or CT angiography must be obtained to differentiate STEMI from dissection before administering thrombolytics or anticoagulation 1

• Unclear diagnosis: When the diagnosis of STEMI is confounded by left bundle branch block, pacing, or atypical presentation, imaging studies including CXR help clarify the clinical picture 1

Common Pitfalls to Avoid

Never wait for CXR results to initiate reperfusion therapy in straightforward STEMI. The most dangerous error is delaying door-to-balloon time or door-to-needle time for non-essential testing. 1 Time is myocardium - every 30-minute delay in reperfusion increases mortality. 1, 3

Do not skip the CXR entirely. While it shouldn't delay treatment, it provides valuable information about alternative diagnoses and complications that will guide subsequent management decisions. 1, 2

Recognize that reperfusion therapy is not contingent on any imaging study when the ECG shows clear ST-elevation and the clinical presentation is consistent with STEMI. 1 The diagnosis is secure based on ECG alone, and treatment should proceed immediately. 1