Despite notable differences between US and European guidelines for the diagnosis and management of syncope, recommendations are similar, according to a review published in the Journal of the American College of Cardiology.

In this review, researchers sought to examine congruencies and differences in syncope guidelines formulated by the American College of Cardiology /American Heart Association/Heart Rhythm Society in 2017 and by the European Society of Cardiology in 2018. Specifically, the purpose of this review was to identify remaining gaps in knowledge and their implications for clinical practice and future research.

Both guidelines state that cerebral hypoperfusion is the presumed mechanism of syncope. However, the US guidelines focus on the clinical conditions underlying the syncope, whereas the European guidelines include both syncope and nonsyncopal forms of real or apparent transient loss of consciousness. There are small content differences within subsections of the respective guidelines on arrhythmias, pediatric syncope, and syncope in patients with comorbidities and frailty. There is notable discordancy on the optimal strategy to approach a syncopal patient who presents with bifascicular block without a manifest atrioventricular block. In the European guidelines, there are discrete recommendations, and there is a lack of specific recommendations in the US guidelines.

The most striking discordancy between the guidelines is the recommendations for β-blockers in treatment of reflex syncope. The European guidelines assign a Class III recommendation, stating that there is no indication for β-blockers, whereas the US guidelines state that β-blockers may represent a reasonable option in patients aged ≥42 years.


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 “[I]t may be difficult for the practitioner to reconcile potential differences when multiple sets of recommendations exist, and carries implications for patient care. Overall, eliminating all differences in any 2 sets of clinical practice guidelines may never be possible. Understanding sources of discordancy is of paramount importance. Even in the era of evidence-based medicine, practitioners will have slightly varied interpretations and opinions of similar data. Despite key discordances, the 2 recent syncope guidelines are complementary,” noted the review authors.

Reference

Goldberger ZD, Petek NJ, Brignole M, et al. ACC/AHA/HRS versus ESC guidelines for the diagnosis and management of syncope: JACC guideline comparison. J Am Coll Cardiol. 2019;74(19):2410-2423.