What is the appropriate workup for near syncope (near fainting) in a patient who has undergone radiation therapy?

From the Guidelines

For a radiation patient experiencing near syncope, a comprehensive workup should be initiated promptly, focusing on orthostatic measurements, hydration status, and medication review, while considering radiation-induced effects on the cardiovascular and neurological systems, as recommended by the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1.

Key Components of the Workup

• Begin with a thorough assessment of vital signs, including orthostatic measurements, and a detailed history focusing on timing of symptoms in relation to radiation treatments.
• Order basic laboratory tests including complete blood count to evaluate for anemia, comprehensive metabolic panel to assess electrolyte abnormalities, and thyroid function tests.
• An electrocardiogram should be performed to rule out cardiac arrhythmias, and consider echocardiography if there are concerns about radiation-induced cardiac effects.
• Hydration status should be carefully evaluated as radiation patients often experience decreased oral intake, nausea, vomiting, or diarrhea leading to volume depletion.
• If orthostatic hypotension is identified, implement a fluid resuscitation protocol with normal saline while monitoring for fluid overload.
• Medication review is essential as many supportive medications used during radiation (antiemetics, pain medications) can contribute to orthostatic hypotension.
• Consider temporary dose adjustments of antihypertensives if the patient is taking them.

Special Considerations

• Neurological evaluation may be warranted if the near syncope occurs with radiation to the head and neck region, as radiation-induced inflammation or edema affecting the carotid sinus or autonomic pathways can contribute to syncope.
• Radiation therapy should continue unless the episodes occur during treatment or immediate post-treatment periods, in which case consultation with radiation oncology for possible treatment modifications is recommended.

Guideline Recommendations

• The 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope recommends a thorough initial evaluation, including history, physical examination, and electrocardiogram, to identify potential causes of syncope 1.
• The guideline also recommends against routine use of neuroimaging, carotid artery imaging, and EEG in the evaluation of syncope, unless there are specific indications based on the patient's history and physical examination 1.

From the Research

Near Syncope Workup in Radiation Patients

• The workup for near syncope in radiation patients involves a thorough history and physical examination, including orthostatic assessment 2, 3.
• A detailed medical history is key to identifying the most likely diagnosis, and subsequent diagnostic tests can be chosen to confirm the clinical suspicion 4.
• Radiation therapy can cause various cardiac problems, including progressive fibrosis, which may induce syncope 5.
• Baroreceptor failure as a sequela of head and neck radiation is a potential cause of syncope in radiation patients 6.
• The evaluation of patients with syncope should include a standardized approach, which reduces hospital admissions and medical costs, and increases diagnostic accuracy 3.
• Short-term risk assessment should be performed to determine the need for admission, and patients with high short-term risk should be admitted to the hospital for further evaluation 2, 3.
• Diagnostic tests such as electrocardiography, laboratory testing, and neuroimaging should be ordered only if clinically indicated 3.
• In cases of unexplained syncope, provocative testing and prolonged electrocardiographic monitoring strategies can be diagnostic 3.

Considerations for Radiation Patients

• Radiation patients with suspected cardiac syncope should undergo monitoring until a diagnosis is made 2.
• Patients with suspected reflex syncope or orthostatic hypotension should undergo outpatient evaluation with tilt-table testing 2.
• Syncope units have been shown to improve the rate of diagnosis while reducing cost and are highly recommended 2.
• Patients with a history of radiation therapy should be evaluated for potential cardiac problems, including progressive fibrosis and baroreceptor failure 5, 6.