The Curbsiders podcast

#442 Live from SHM #Converge24 Syncope with Dr. Dan Dressler

June 3, 2024 | By



Transcript available via YouTube

Don’t pass up on passing out!

Stand up to syncope as Dr. Dan Dressler (Emory University) guides us to confidently manage cases! We review a framework for understanding different types of syncope, and strategies for determining which low-risk patients can be safely discharged, and appropriate next steps to work up those high-risk and in-between cases. 

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Show Segments

  • Intro
  • Picks of the Week
  • Case 1: Tamara
  • What is syncope?
  • Categorizing Syncope
  • Initial workup
  • Risk scores
  • Pulmonary embolism 
  • Case 2: Travis
  • Cardiac evaluation
  • Take-home points
  • Outro

Syncope Pearls

  1. Make sure to do a good history and exam- including a complete cardiac and neurologic exam. Ask about vasovagal prodromal symptoms, and don’t forget your orthostatics!
  2. Limited myoclonic jerking,  incontinence, or <10 seconds of post-episode confusion may be seen in syncope. Tonic-clonic movements, loss of consciousness > 30 seconds, lateral tongue biting, and minutes of post-episode confusion are suggestive of seizure (Brignole, 2018).
  3. Most cases of syncope that have low-risk causes can be identified from the initial history, physical exam, and electrocardiogram (Van Dijk, 2007).
  4. Risk scoring systems, like the well-validated Canadian Syncope Risk Score, can be helpful to identify those with elevated risk for high-risk causes (calculators available such as QxMD and MDCALC).
  5. Neurologic testing is only required in those with history or exam findings concerning for neurologic causes like seizure or stroke (Brignole, 2018).
  6. Reserve echocardiogram for patients whose history, physical, or electrocardiogram reveal abnormal cardiac findings (Madeira, 2017).
  7. Per Dr. Dressler’s practice, if there is not clearly a low-risk or high-risk etiology of a patient’s transient loss of consciousness, consider a Simplified Well’s Score and D-dimer to rule out PE. 

Syncope Show Notes

What is syncope?

  • Syncope is a transient loss of consciousness and postural tone that occurs suddenly due to decreased cerebral blood flow and which is followed by spontaneous recovery (Brignole, 2018). 
  • Other etiologies of transient loss of consciousness (e.g. hypoglycemia, seizure, concussion, psychogenic, etc) are NOT considered syncope. 
  • Presyncope (or near syncope) is the prodrome of syncope in the absence of transient loss of consciousness (for example, in a person who has used countermeasures like sitting or lying down to avoid syncope). Presyncope and syncope have a similar prognosis (Greve, 2014; Grossman, 2010). 

How should we categorize syncope? (Jhanjee, 2009)

History and Physical Exam

While most cases of syncope are due to benign causes, a small number of patients may have underlying life-threatening causes that can be challenging to identify.  Fortunately, most cases of syncope are caused by low-risk etiologies (e.g. vasovagal episode, volume depletion) and can be diagnosed based on the history, physical exam, and electrocardiogram (Van Dijk, 2007). Full cardiac and neurological physical examinations should be completed and well-documented. ECG should be performed in all patients. Consider the patient’s prior history and cardiac diseases which may contribute to a syncope presentation. 

Common findings to look for:

  • Vasovagal prodrome: Look for a constellation of relevant symptoms that may suggest a sympathetic surge (e.g. palpitations, anxiety, diaphoresis) and the subsequent parasympathetic surge (e.g. warmth, nausea, vomiting).
  • Incontinence: This can occur with both seizure and syncope, and so it has little diagnostic value in distinguishing them (Brigo, 2013).
  • Jerking: Jerking movements may occur in both syncope and seizure. The myoclonic jerking of syncope is often < 10 seconds, irregular myoclonic jerks, with unconsciousness lasting < 30 seconds. Tonic-clonic movements or unconsciousness (lasting 30 seconds or more) or with an unconsciousness episode lasting longer are more suggestive of seizure (Brignole, 2018). 
  • Tongue Biting: often lateral, is more suggestive of seizures, with  a high positive likelihood ratio of 8.6 in unwitnessed loss of consciousness episodes (Brigo, 2012; Cooper, 2011).  
  • Post-confusion: The return to full alertness occurs within <10 seconds in most cases of syncope; return to full alertness can take minutes after seizures (Brignole, 2018).

Don’t forget:

  • Orthostatic blood pressure and heart rate measurements: Always check the orthostatics! (Shen, 2017) Dr. Dressler reminds us it is never too late, since some patients may remain hypovolemic after fluids, and others may have a drop in blood pressure without compensatory heart rate response suggesting autonomic dysfunction.

Risk Scoring Systems

  • Several risk scoring systems have been developed in the past few decades, though none have optimal performance.
  • The Canadian Syncope Risk Score (2016) has been validated in large international cohorts (Zimmerman, 2022).
  • Calculators are available on QxMD and MDCALC.

Cardiac workup

  • An electrocardiogram should be obtained on all patients (Rusner, 2017).
  • Troponins are indicated when there is concern for ischemia, but there is limited data to support testing in all-comers with syncope (Shen, 2017). 
  • Consider stress testing if chest pain is present, and in cases of exertional syncope (Goldberger, 2019).
  • Reserve echocardiography for selected patients with cardiac symptoms, abnormal physical exam findings, or ECG abnormalities (Madeira, 2017).
  • Consider cardiology consultation for guidance on specialized testing in cases of suspected arrhythmia: for example, electrophysiologic study (EPS) or implantable loop recorders (ILR) (Goldberger, 2019)
    • In >80% of patients with syncope and a wide QRS ( ≥ 120 ms), a specific diagnosis can be reached with a sequential evaluation: initial evaluation, EPS (if initial eval nondiagnostic), and ILR (if EPS nondiagnostic) (Moya, 2011). 
    • Causes include bradyarrhythmias, ventricular tachycardia, and other diagnoses requiring intervention.
  • Inpatient and outpatient rhythm monitoring can be considered for patients with syncope due to a suspected arrhythmia (Brignole, 2018):
    • Telemetry can be done for in-hospital monitoring during admission.
    • Holter monitors record continuously for 24-48 hours, thus may be valuable if symptoms are frequent.
    • Loop recorders capture events but do not continuously record. There are two types: External loop recorders adhere to the skin and can be used for weeks (as tolerated) or implantable loop recorders are placed subcutaneously and can be used for months to years to capture rare events.
    • Dr. Dressler generally doesn’t consider outpatient monitoring for first episodes of syncope, unless palpitations are a predominant symptom or a patient has experienced several episodes of syncope without a clear cause and with a frequency that may be captured with a device.

When should you worry about pulmonary embolism?

  • The PESIT Study (Prandoni, 2016) was a prospective study in 11 Italian hospitals that evaluated adults admitted for their first episode of syncope for pulmonary embolism (PE). 72% of patients presenting to the ED with syncope were discharged home. All admitted patients (excludes patients with low-risk etiologies who were discharged from ED) underwent an initial screening for PE with a Simplified Well’s Score and D-Dimer:
    • Pulmonary embolism was excluded in ~40% who had a low score and a negative D-Dimer.
    • Patients with an elevated Simplified Wells Score and/or D-Dimer underwent CT pulmonary angiography or ventilation-perfusion (V/Q) lung scan – of these, 42% were diagnosed with PE. 
    • In total, PE was found in 17% of all adults admitted for a first syncopal episode, or 4% of those presenting to the ED with first syncope.
  • Dr. Dressler’s expert-opinion practice: He considers testing for PE in admitted patients who are in a gray zone– those who are neither low-risk (who could be discharged without further workup) nor clearly have an alternate high-risk diagnosis. In these cases he calculates a simplified Well’s score and obtains a D-dimer, followed by imaging if the D-dimer is abnormal.
  • Additional studies have followed, though are mostly retrospective, with variable definitions of syncope, and are of generally lower-quality. One large study on prospective cohorts in US and Canada demonstrated a PE prevalence of 0.6% among all presenting to the ED (Thiruganasambandamoorthy, 2019
  • While most PEs in PESIT led to large perfusion defects (>25% of lung area), ~⅓ had small PEs. While it is not clear why small PEs might lead to syncope, Dr. Dressler notes that PE and the related inflammation may activate lung receptors and lead to vasovagal episodes.

Neurologic and other testing

  • Further neurological testing like EEG or neuroimaging should be reserved for patients with high suspicion for stroke or seizure (e.g. jerking movements that are prolonged or tonic-clonic, lateral tongue biting, or a post-ictal state) (Brignole, 2018).
  • Head/brain imaging is not recommended in simple syncope in asymptomatic patients with normal neurological exams in the absence of significant trauma, as per the Choosing Wisely recommendations from the American College of Physicians and American College of Emergency Physicians (Rusner, 2017). 
  • Carotid artery imaging is not recommended in simple syncope without other neurologic symptoms, as per Choosing Wisely recommendations from the American Academy of Neurology (Gould, 2013).
  • Tilt-table testing: See the European Society of Cardiology syncope guidelines (Brignole, 2018), which covers different scenarios including when to consider tilt-table testing.


  • For simple, low-risk syncope, Dr. Dressler generally describes this to patients as a “simple faint” and provides reassurance.
  • When prodromal symptoms arise, individuals should use countermeasures like sitting or lying down where possible.
  • Staying well hydrated, even drinking a large glass of water, may help prevent syncope if entering a situation that may provoke it, such as giving blood (Lu, 2003).


  1. You Are So Not Invited to My Bat Mitzvah (Netflix)
  2. Superbad
  3. The Paperbag Princess
  4. Zoolander
  5. Dune 2


Listeners will confidently have a framework to classify and workup syncope presentations. 

Learning objectives

After listening to this episode listeners will…

  1. Use a framework for understanding different types of syncope
  2. Confidently counsel patients on non pharmacological measures for vasovagal and orthostatic hypotension-related syncope
  3. Recognize high-risk features that should prompt further evaluation versus low-risk cases
  4. Strategically tailor diagnostic testing to individual cases
  5. Risk-stratify for syncope related to potential pulmonary embolism for further workup


Dr. Dressler reports no relevant financial disclosures. The Curbsiders report no relevant financial disclosures. 


Okamoto E, Dressler D, Amin M, Trubitt M “#442 Syncope with Dan Dressler”. The Curbsiders Internal Medicine Podcast. Final publishing date June 5, 2024.

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Episode Credits

Producer, Script and Show Notes: Emi Okamoto MD
Infographic and Cover Art: Caroline Coleman MD
Hosts: Monee Amin MD and Meredith Trubitt MD
Reviewer: Rahul Ganatra MD, MPH
Showrunners: Matthew Watto MD, FACP; Paul Williams MD, FACP
Technical Production: PodPaste
Guest: Daniel D. Dressler, MD, MSc, MHM, FACP

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