Do I order a CT (computed tomography) scan to rule out pulmonary embolism (PE) in a patient with palpitations, tachycardia, and elevated troponin levels?

From the Guidelines

A CT pulmonary angiogram (CTPA) is not automatically indicated for a patient with only palpitations, tachycardia, and elevated troponin levels, as these findings alone are not specific for pulmonary embolism (PE). Instead, first assess the patient's clinical probability of PE using validated tools like the Wells score or Geneva score 1. If the patient has additional risk factors for PE (recent immobilization, surgery, cancer, hormonal therapy, prior DVT/PE), respiratory symptoms (dyspnea, pleuritic chest pain), signs of DVT, or unexplained hypoxemia, then their pre-test probability increases. For patients with intermediate to high pre-test probability, order D-dimer testing first. If D-dimer is elevated, proceed with CTPA. For patients with high clinical suspicion, you may proceed directly to CTPA. The symptoms you described could represent other cardiac conditions like acute coronary syndrome, myocarditis, or arrhythmias, which should be considered in your differential diagnosis 1. A focused history, physical examination, ECG, and chest X-ray are essential components of the initial evaluation before deciding on advanced imaging.

Some key points to consider:

• Elevated troponin levels can be seen in various conditions, including myocardial infarction, myocarditis, and pulmonary embolism 1
• The diagnostic challenge of PE is most commonly addressed with clinical scoring algorithms, D-dimer testing, and specialized CT angiography (CTA) 1
• Technological advancements have allowed accurate evaluation of the pulmonary vasculature, thoracic aorta, and coronary arteries on a single CT study for patients with acute chest pain, but this "triple rule out" CT protocol has yet to be proven useful through large-scale clinical trials 1

Given the most recent and highest quality study available 1, it is recommended to first assess the patient's clinical probability of PE and proceed with D-dimer testing or CTPA based on the pre-test probability, rather than automatically ordering a CT scan. This approach prioritizes the patient's morbidity, mortality, and quality of life by minimizing unnecessary testing and focusing on the most likely diagnoses.

From the Research

Patient Presentation

The patient presents with palpitations, a heart rate of 200 as shown on the Apple Watch, and elevated troponin levels (initially 17 and increasing to 39).

Diagnostic Considerations

• The elevated troponin levels indicate myocardial injury, but this can occur in various conditions, not just acute coronary syndromes 2.
• Conditions such as sepsis, hypovolemia, atrial fibrillation, congestive heart failure, pulmonary embolism, myocarditis, myocardial contusion, and renal failure can also cause troponin elevation 2.
• A case study showed that prolonged supraventricular tachycardia can lead to elevated troponin levels even with normal coronary angiography 3.

Imaging Studies

• A CT scan can be useful in ruling out pulmonary embolism (PE), especially in patients with elevated troponin levels and no clear evidence of acute coronary syndrome 4.
• The triple-rule-out (TRO) CT scan can help exclude coronary artery disease, acute aortic syndrome, and pulmonary embolism 4.
• Late contrast enhancement (LCE) CT scans can provide additional diagnostic information, such as identifying myocarditis, takotsubo cardiomyopathy, or amyloidosis 4.

Decision Making

• Given the patient's presentation and elevated troponin levels, it is essential to consider alternative causes of troponin elevation, including pulmonary embolism 2.
• Ordering a CT scan to rule out PE may be appropriate, especially if other diagnostic tests, such as electrocardiography and echocardiography, are inconclusive 4.
• The decision to order a CT scan should be based on the patient's overall clinical presentation, medical history, and the results of other diagnostic tests 5, 4.