• acute coronary syndrome
• organisational objectives

The European Society of Cardiology (ESC) clinical practice guideline for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation was updated in 2020.1 Here, we highlight and discuss some of the notable changes (table 1) focusing on the diagnostic pathway, decision-making regarding coronary imaging and optimal antithrombotic strategy.

The previous ESC clinical practice guideline recommended the use of high-sensitivity cardiac troponin testing and accelerated sampling intervals to rule in or rule out myocardial infarction earlier. The central recommendation was a 0/3-hour pathway using the 99th centile upper reference limit to rule out myocardial infarction.2 Studies have since shown that the ESC 0/3-hour pathway missed up to 1 in 10 patients, with myocardial infarction detected at later time points and this pathway is no longer recommended.3 Multiple studies now support the superior safety and efficacy of using thresholds well below the 99th centile to rule out myocardial infarction and in recognition of this, the new guideline advocates a single troponin measurement in patients presenting at least 3 hours from symptoms onset.4 Myocardial infarction can be safely ruled out if concentrations are ‘very low’ and ruled in if values are ‘high’ using multiple assay-specific thresholds. Repeat testing at 1 or 2 hours is recommended for those presenting early or with ‘low’ but detectable concentrations on arrival.5 However, for patients with intermediate troponin concentrations, which may be up to a third of those assessed, the guideline recommends further observation and investigation, creating potential uncertainty for clinicians. The sole randomised trial assessing the safety and effectiveness of implementing the ESC 0/1-hour pathway was stopped prematurely with only a small number of safety outcomes accrued following discharge from hospital.6 It provided little insight into the role of further investigation in …