Syncope is an commonly encountered problem in Emergency Medicine, with the potential for significant morbidity and mortality to patients. Unfortunately, to date, there have not been any reliable decision tools or instruments to help us in our assessment of the syncope patient.  This week, Venkatesh Thiruganasambandamoorthy and colleagues at the Ottawa Hospital have published an new Canadian Syncope Risk Score to identify patients at risk of serious adverse events, published in CMAJ.1 Here, Dr. Venk helps provides some further insight and potential utilization of the risk score, he may also be heard discussing this rule on the March edition of Canadian EMRAP.


Syncope constitutes 1% of Emergency Department (ED) visits, and approximately 10% of these patients will have serious underlying conditions causing syncope (arrhythmia, MI, serious structural heart disease, pulmonary embolism, subarachnoid or severe hemorrhage). Alarmingly, half to one-third of these serious conditions will not be identified during ED evaluation.
We conducted a prospective multicenter cohort study at 6 large Canadian ED’s and enrolled 4,030 adult syncope patients to derive the Canadian Syncope Risk Score to identify the risk of serious adverse events within 30-days of ED disposition. The risk tool consists of nine predictors, with the score for each predictor ranging  from -2 to +2 with a potential total score of -3 to +11:
  • Vasovagal predisposition 
  • Heart Disease
  • Any ED systolic BP < 90 or > 180 mmHg
  • Troponin (>99%ile)
  • Abnormal QRS axis (<-30 or >100), QRS duration >130 ms, or QTc interval > 480 ms
  • ED diagnosis of cardiac or vasovagal syncope

How to utilize this score

Upon initial evaluation of the syncope patient, if you are fairly certain as to the cause of the patient’s syncope, that should (obviously) be managed accordingly. In patients where a diagnosis of vasovagal syncope is suspected, the patient only requires an ECG prior to discharge. When there is any doubt as to the potential etiology of the patient’s presentation, utilize the Canadian Syncope Risk Score to estimate the risk of serious adverse event in the next 30-days. The serious adverse events include conditions that need to be detected (MI, structural heart disease, bleeding, pulmonary embolism) and those that need to be predicted (arrhythmia, death). If the patient is deemed high-risk as per the score, it is imperative to carefully evaluate the patient and conduct further investigations as required. If you are confident that all serious conditions that need to be detected are reasonably unlikely, the one remaining etiology is arrhythmia, which may be difficult to detect in the ED (see below for more on this). If there is a high suspicion for significant pathology (i.e. early sepsis, occult GI bleeding), admission of the patient is strongly suggested. Ultimately, this is a small proportion of patients; in this study cohort, only 6.7% of patients were considered ‘high-risk’.


We are also in the process of deriving a risk tool (Canadian Syncope Arrhythmia Risk Score; submitted for publication) specifically for predicting arrhythmias. This tool will help to identify patients who will benefit from prolonged cardiac monitoring in the setting of syncope. In this study cohort only 0.3% of patients suffered ventricular arrhythmias and 0.3% died from unknown causes. The risk of ventricular arrhythmia is low, and the key will be to identify which patients are at risk for this.

How will Syncope care look in the future?

Utilize the Canadian Syncope Risk Score to identify patients at risk for all serious outcomes and evaluate higher-risk patients for potentially non-arrhythmic serious conditions. The Canadian Syncope Arrhythmia Risk Score may be potentially useful in identifying patients who are at risk for serious arrhythmias. If they are at risk for ventricular arrhythmia (likely risk factors include CHF with poor ejection fraction, cardiomyopathy, cardiomegaly, wide QRS, prolonged QT, significant cardiac abnormalities – Brugada, HOCM etc.) then the patient should be admitted. If the patient is high-risk for arrhythmia, but ventricular arrhythmia is less likely, they may discharge home with a prolonged monitoring device.
Dr. Venkatesh Thiruganasambandamoorthy is an attending physician and associate scientist at the Ottawa Hospital and Ottawa Hospital Research Institute with an particular interest in syncope and presyncope care. 
Edited by Dr. Shahbaz Syed, PGY-5 Emergency Medicine resident at the University of Ottawa


Thiruganasambandamoorthy V, Kwong K, Wells GA, et al. Development of the Canadian Syncope Risk Score to predict serious adverse events after emergency department assessment of syncope. Canadian Medical Association Journal. July 2016. doi:10.1503/cmaj.151469.