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

Abstract

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 (<5 ng/L). With no AMIs in this group, the negative predictive value (NPV) and sensitivity were both 100.0% (95% CI 99.4% to 100.0% and 94.1% to 100.0%, respectively), and the specificity 34.5% (32.2% to 36.8%). The original HEART score triaged more patients as low risk (n=871), but missed five AMIs (NPV 99.4% (98.7% to 99.8%); sensitivity 91.8% (81.9% to 97.3%) and specificity 52.5% (50.0% to 54.9%)). The modified HEART score increased the low-risk sensitivity to 98.4% (91.2% to 100.0%), with specificity 38.7% (36.3% to 41.1%). The 90-day incidence of AMI or death in the single rule-out and the original and modified low-risk HEART groups were 0.0%, 0.7%, and 0.2%, respectively.

Conclusion: In a primary care emergency setting, a single hs-cTnT strategy was superior to the HEART score in ruling out AMI. This rapid and safe approach may enhance the assessment of patients with chest pain outside of hospitals.

Trial registration number: NCT02983123.

Keywords: accident & emergency medicine; coronary heart disease; ischaemic heart disease; myocardial infarction; primary care.

Conflict of interest statement

Competing interests: None declared.

© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

Figures

Figure 1

Patient flow chart. Study enrolment at the primary care emergency clinic during the OUT-ACS study. *Critically ill patients are brought directly to hospital by the ambulance services. ACS, acute coronary syndrome; hs-cTnT, high-sensitivity cardiac troponin T; OAEOC, Oslo Accident and Emergency Outpatient Clinic; OUT-ACS, One hoUr Troponin in a low-prevalence population of Acute Coronary Syndrome.

Figure 2

The diagnostic and prognostic safety of the three rule-out strategies at the primary care emergency clinic. AMI, acute myocardial infarction; HEART, History, ECG, Age, Risk factors and Troponin; hs-cTnT, high-sensitivity cardiac troponin T; NPV, negative predictive value; NSTE-ACS, non-ST-segment elevation acute coronary syndrome.

Figure 3

The overall diagnostic performance of the single hs-cTnT strategy, the original HEART score and the modified HEART score were illustrated by the AUC, which was achieved using the predefined cut-off values for the three different strategies. The single hs-cTnT rule-in and high-risk HEART groups are shown in the lower-left corner, the single hs-cTnT rule-out and low-risk HEART groups in the upper right. The large intermediate groups represent the patients in need of further tests. AUC, area under the curve; HEART, History, ECG, Age, Risk factors and Troponin; hs-cTnT, high-sensitivity cardiac troponin T.