Comparison of a single high-sensitivity cardiac troponin T measurement with the HEART score for rapid rule-out of acute myocardial infarction in a primary care emergency setting: a cohort study

Objective This study aims to compare the rule-out safety of a single high-sensitivity cardiac troponin T (hs-cTnT) with the History, ECG, Age, Risk factors and Troponin (HEART) score in a low-prevalence primary care setting of acute myocardial infarction (AMI). Participants Patients with non-specific symptoms suggestive of AMI were consecutively enroled at a primary care emergency clinic in Oslo, Norway from November 2016 to October 2018. Methods After initial assessment by a general practitioner, hs-cTnT samples were drawn. AMI was ruled-out by a single hs-cTnT <5 ng/L measured ≥3 hours after symptom onset. The HEART score was calculated retrospectively; a score ≤3 of 10 points was considered low risk. We also calculated a modified HEART score using more sensitive hs-cTnT thresholds. The primary outcome was the diagnostic performance for the rule-out of AMI at the index event; the secondary the composite of AMI or all-cause death at 90 days. Results Among 1711 patients, 61 (3.6%) were diagnosed with AMI, and 569 (33.3%) patients were assigned to single rule-out (