Emergency Department Validation of Canadian Syncope Risk Score

Study Questions:

Can the Canadian Syncope Risk Score (CSRS) predict 30-day serious outcomes in patients presenting to the emergency department (ED) with syncope?

Methods:

This was a prospective cohort study involving nine Canadian EDs between 2014 and 2018. Study patients were included unless a serious underlying condition was discovered during the index evaluation or if confounding factors (e.g., trauma, seizure, mental status change, alcohol intoxication, or prolonged loss of consciousness over 5 minutes was involved) were present. Serious outcomes at 30 days were adjudicated as arrhythmic (arrhythmia requiring an intervention or unknown cause of death) or nonarrhythmic (myocardial infarction, structural heart disease, pulmonary embolism, or hemorrhage). Outcomes were ascertained by a combination of medical record review, telephone interviews, and coroner database searches. Comparison, calibration, and discrimination statistics were applied.

Results:

Out of a total 3,819 included patients, 2,088 (54.7%) were female and 139 (3.6%) experienced 30-day serious outcomes; 107 (2.8%) had arrhythmic outcomes, and of these, nine (0.2%) died due to an unknown cause. Proportion of risk for any serious outcome increased significantly by grouping: 3 of 1,631 at very low risk, or 0.3%; 55 of 687 at medium risk, or 8%; and 40 of 78 at very high risk, or 51.3%. The proportion of arrhythmic risk increased similarly among the groups. Eight-nine patients (90%) of the 99 in the medium- to very high-risk groups had their arrhythmia identified within 15 days of the ED visit. There were no significant differences between expected versus observed risk.

Conclusions:

The CSRS accurately risk stratifies patients presenting to the ED with syncope. Less than 1% of very low- to low-risk patients, 20% of high-risk patients, and 50% of very high-risk patients experience serious outcomes within 30 days of the ED visit.

Perspective:

  • The CSRS assigns weighted points in three areas: 1) Clinical evaluation (predisposition to vasovagal symptoms, history of heart disease, any systolic blood pressure <90 or >180 mm Hg), 2) Investigations (elevated troponin level [>99th percentile), abnormal QRS axis, QRS >130 ms), and 3) Diagnosis in ED (vasovagal syncope, cardiac syncope).
  • Online calculators for the CSRS are available.
  • A study from the same group evaluated the role of 15-day electrocardiology (ECG) monitoring in select patients (Circulation 2019;139:1396-1406).
  • Some limitations, as noted by the authors, include: 1) up to 20% of eligible patients were not enrolled; 2) awareness of the CSRS by ED physicians, especially after the initial report in 2016, likely influenced future evaluations; 3) if troponins and ECGs were not performed, a subject was still included and those variables were imputed as “normal.”
  • This study supports the use of the CSRS in guiding disposition decisions in very low- to medium-risk patients, but calculating the CSRS relies on diagnostic impression.
  • So a good history and physical remains paramount in the evaluation of syncope.

Clinical Topics: Arrhythmias and Clinical EP, Prevention, Vascular Medicine, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias

Keywords: Arrhythmias, Cardiac, Blood Pressure, Electrocardiography, Ambulatory, Emergency Medical Services, Hemorrhage, Myocardial Infarction, Outcome Assessment (Health Care), Pulmonary Embolism, Risk Assessment, Risk Factors, Secondary Prevention, Syncope, Syncope, Vasovagal, Troponin


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