Author: Dr. Tucker Matthews


Lots of patients in the ED present after a syncopal episode, but we don’t do a good job of choosing which patients need further monitoring and/or admission. We have risk stratification tools, but they don’t really tell us what to do with high risk or medium risk or low risk patients. This leads to many of these patients developing dangerous arrhythmias or other adverse outcomes after they leave the hospital. So, it would be great if we had clear guidelines for how to manage patients stratified into the various groups. The group doing this study is actually the same group that developed the Canadian Syncope Risk Score, which is the score that they (shockingly) use to stratify patients for the study.

Study Question

How long should we be monitoring patients who present after a syncopal episode? And in which setting should they be monitored?


They did an observational prospective cohort study, enrolling any adult coming to one of 6 EDs within 24 of syncopal event. They then investigated the rates of arrhythmias and other serious adverse outcomes within the 30 day period following the index ED visit. FYI, apparently Canada is really great for this because all medical records are in one central database.


To quote the authors: “One-half of arrhythmic outcomes were identified within 2 hours of ED arrival in low-risk patients and within 6 hours in medium- and high-risk patients, and the residual risk after these cut points were 0.2% for low-risk, 5.0% for medium-risk, and 18.1% for high-risk patients. Overall, 91.7% of arrhythmic outcomes among medium- and high-risk patients, including all ventricular arrhythmias, were identified within 15 days.”


Unsurprisingly, low risk patients can just be discharged within 2 hours (which is pretty much the time required to get a troponin result anyway, which is required for the stratification score). For medium and high risk patients, on the other hand, they recommend monitoring for 6 hours in the ED at a minimum because that’s when the majority of adverse outcomes occur. That being said, there’s still a pretty decent rate of adverse events after that window, even for patients at the lower end of the medium risk group, so there’s no clear way to specify which patients would benefit from admission vs. outpatient cardiac monitoring. Their findings are definitely a good start to begin to clarify management for these patients, but they aren’t really saying anything super wild here, and ultimately, the medium and high risk patients are the kind of folks who we would probably be monitoring or admitting anyways, since they by definition probably have either a history of heart disease, some abnormal vitals or ECG findings, or an elevated troponin. So, I don’t personally feel like this study would alter my management significantly, though if further studies can better clarify which medium or high risk patients require admission, that could be really helpful. Finally, the fact that the score requires a troponin is a bit weird since there are certainly loads of syncope patients who I wouldn’t think to send that, but now I guess maybe I should, so I can be sure to be able to use this scoring system.


Low risk patients presenting after syncope can be discharged, but anyone who has a hint of cardiogenic etiology should at a minimum be watched in the ED for 6 hours, and should have admission considered.


Thiruganasambandamoorthy V, Kwong K, Wells GA, Sivilotti ML, Mukarram M, Rowe BH, Lang E, Perry JJ, Sheldon R, Stiell IG, Taljaard M. Development of the Canadian Syncope Risk Score to predict serious adverse events after emergency department assessment of syncope.CMAJ. 2016; 188:E289–E298. doi: 10.1503/cmaj.151469

Thiruganasambandamoorthy V, et al. Duration of Electrocardiographic Monitoring of Emergency Department Patients With Syncope. Circulation. 2019; PMID: 30661373

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