An EM Approach to Syncope in Adults

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Medical Student Pearl

Samarth Fageria

Med 3

Memorial University of Newfoundland Class of 2024

Reviewed by Dr. J Gross

Copy Edited by Dr. J Vonkeman

Pdf Download: EMSJ An EM Approach to Syncope by SFargeria

 

Case

A 60-year-old male presented to the ED after experiencing recurrent episodes of syncope. The first episode occurred at a convenience store in an upright position. He denied prodrome and exertional activity at the time of syncope. After a transient loss of consciousness, he woke up confused with urinary incontinence. He felt nauseous and had emesis in the ambulance on the way to ED. He had two more episodes of syncope over the span of two hours. On assessment in the ED, he endorsed a past history of light-headedness preceded by laughing and holding his breath. He denied dyspnea and chest pain. He had no significant past medical history. There was no family history of cardiovascular disease and syncope, and social history was unremarkable.

 

On examination, he was alert and oriented. He had a minor laceration on his forehead from the fall. His respiratory and cardiovascular exams were unremarkable, neurological exam was normal. In the ED, his blood work was unremarkable. He was placed on telemetry when he had two more episodes of syncope. The monitor showed 20-second-long sinus pauses corresponding with the syncopal episodes. Cardiology was consulted and he was temporarily placed on intermittent transcutaneous pacing.

 

 

Differential Diagnosis of Syncope2

True Syncope

1. Reflex (autonomic hypersensitivity)

  • Vasovagal, carotid sinus hypersensitivity, situational

2. Orthostatic hypotension

  • Volume depletion, autonomic failure

3. Cardiac

  • Valvular (aortic stenosis, mitral stenosis), dysrhythmias (bradyarrhythmia, ventricular tachyarrhythmia, supraventricular tachyarrhythmia), mechanical (pacemaker dysfunction), cardiomyopathy, infiltrative (eg. hemochromatosis, sarcoidosis, amyloidosis), acute MI, ARVC, cardiac tamponade, acute aortic dissection

Other Causes

1. Medication/ Drug-induced

  • Anti-hypertensives, QT prolonging meds, insulin, alcohol, anti-depressants, anti-glycemic agents, diuretics, anti-anginal agents, etc

2. Transient Loss of Consciousness (TLOC)

    • Traumatic brain injury, seizure disorders, intoxications, hindbrain TIA, conversion disorders and metabolic abnormalities

 

Background

Syncope is defined as a brief, sudden, transient loss of consciousness due to cerebral hypoperfusion1. The three broad categories of syncope are reflex, orthostatic and cardiac syncope. The most common cause of cardiac syncope includes dysrhythmias1. A good past medical history of cardiovascular disease is important as it is 85-94% sensitive and 64-83% specific in predicting a cardiac etiology of syncope1.

Diagnostic Workup

Diagnostic workup for syncope requires a thorough history, physical exam, and a 12-lead ECG. Cardiac monitoring is necessary in patients that present to ER with an acute presentation of syncope, and a strong suspicion for cardiac etiology2. History should consist of identifying high-risk features that warrant a prompt cardiology consult2. A detailed HPI should consist of asking about an absence of a prodrome, exertional or supine syncope, concomitant trauma, past medical history of cardiovascular disease and family history of sudden cardiac death (<50 years)2. Low-risk features include presence of a prodrome, specific triggers (eg. dehydration, stress, laughter), syncope while upright and the absence of cardiovascular disease2. Vital signs and a cardiac exam should be completed2. If cardiac causes of syncope cannot be ruled out on first assessment, a 12-lead ECG should be placed to assess for dysrhythmias or conduction disease, and serial troponin values should be collected2.

 

Though there are multiple clinical decision rules for syncope, the following have been externally validated: Evaluation of Guidelines in Syncope Study (EGSYS), San Francisco Syncope Rule and Osservatorio Epidemiologico sulla Sincope nel Lazio (OESIL)1. Patients that are stratified as high risk require admission for further evaluation. EGSYS predicts the probability of cardiac syncope at two years based on abnormal ECG findings (eg. BBB, sinus bradycardia), heart disease (eg. ischemic, structural), palpitations before syncope, as well exertional and positional syncope, symptoms of prodrome (nausea/vomiting) and predisposing/precipitating factors1. An admission is warranted if the patient scores a three or higher as there is a 21% mortality risk at two years1. The OESIL risk score estimates a 1-year all-cause mortality in patients presenting with syncope1. The factors include age (>65), history of cardiovascular disease, lack of prodrome and abnormal ECG characteristics (eg. BBB, AV conduction disorders and hypertrophy)1. Admission is warranted for one or more variables1. The Canadian Syncope Risk Score can be used in patients presenting to ER with syncope to predict a 30-day serious adverse events2.  It consists of factors such as abnormal QRS axis, corrected QT interval >480 ms, elevated troponin (>99th percentile of normal population) and ED diagnosis based on evaluation to stratify patients into risk categories: very low (-3 to -2), low (-1 to 0), medium (1 to 3), high (4 to 5) and very high (6 to 11)2.

The Canadian Journal of Cardiology recommends a disposition algorithm for patients presenting to ER with syncope that is based on history of a serious medical condition and high-risk features3. Figure 1 illustrates an approach to disposition from the ER. Patients that have an unclear etiology and intermediate risk should be considered for an urgent cardiology assessment.

 

Figure 1: A disposition plan for patients presenting to the ER with syncope (Canadian Cardiovascular Society 2020).

Best Practice for Treatment

Given the benign course, treatment for vasovagal syncope is based on lifestyle modification, education and reassurance2. Lifestyle modification consists of educating patients on identifying and managing prodromes early and managing triggers (eg. dehydration, defecation, micturition, laughing, coughing and crowded environments)2.

Treatment for orthostatic syncope also relies on lifestyle modification, education and reassurance2. Lifestyle modification consists of re-adjusting diuretics, ACE-inhibitors, angiotensin receptor blockers, calcium channel and beta blockers to ensure optimal blood pressure and hydration control2.

Managing cardiac syncope requires addressing the underlying etiology through antiarrhythmic medications (eg. tachyarrhythmias), cardiac pacing (eg. bradyarrhythmias), catheter-directed ablation and ICD insertion1. Cardiac pacemaker therapy is indicated for patients that have intermittent sinus node disease if correlation is identified between sinus pauses on ECG and syncope3. Selected patients that are diagnosed with the bradycardia-tachycardia form of sick sinus syndrome, can benefit from a percutaneous cardiac ablative technique3.  Dual-chamber pacing is recommended for patients with sinus node dysfunction provided there is an increased risk of AV block4.

Case continued

The patient was admitted and had no further asystole after receiving atropine and intermittent transcutaneous pacing. He was accepted for a dual-chamber pacemaker insertion and was discharged with the diagnosis of syncope with sinus arrest and vagal overtones.

Take Home Points

  1. Patients presenting to the ER with new-onset syncope require a thorough history and physical exam to rule out cardiogenic causes.
  2. Validated clinical decision-making tools can be helpful to supplement clinical judgement for assessing the risk of a future cardiac event, identifying the need for a cardiology consult and creating a disposition plan.

References

  1. Runser LA, Gauer RL, Houser A. Syncope: Evaluation and Differential Diagnosis. Am Fam Physician. 2017;95(5):303-312. https://www.aafp.org/pubs/afp/issues/2017/0301/p303.html#:~:text=A%20standardized%20approach%20to%20syncope,%2C%20physical%20examination%2C%20and%20electrocardiography
  2. UpToDate. www.uptodate.com. https://www.uptodate.com/contents/syncope-in-adults-clinical-manifestations-and-initial-diagnostic-evaluation
  3. Sandhu RK, Raj SR, et al. Canadian Cardiovascular Society Clinical Practice Update on the Assessment and Management of Syncope. Can J Cardiol. 2020;36(8):1167-1177. doi:10.1016/j.cjca.2019.12.023 https://www.onlinecjc.ca/article/S0828-282X(19)31549-1/fulltext
  4. Brignole M, Moya A, de Lange FJ, et al. 2018 ESC Guidelines for the diagnosis and management of syncope. Eur Heart J. 2018;39(21):1883-1948. doi:10.1093/eurheartj/ehy037https://academic.oup.com/eurheartj/article/39/21/1883/4939241?login=false
  5. Dakkak W, Doukky R. Sick Sinus Syndrome. In: StatPearls. Treasure Island (FL): StatPearls Publishing; July 18, 2022. https://www.ncbi.nlm.nih.gov/books/NBK470599/

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