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Abstract
Background The original Manchester Acute Coronary Syndromes model (MACS) ‘rules in’ and ‘rules out’ acute coronary syndromes (ACS) using high sensitivity cardiac troponin T (hs-cTnT) and heart-type fatty acid binding protein (H-FABP) measured at admission. The latter is not always available. We aimed to refine and validate MACS as Troponin-only Manchester Acute Coronary Syndromes (T-MACS), cutting down the biomarkers to just hs-cTnT.
Methods We present secondary analyses from four prospective diagnostic cohort studies including patients presenting to the ED with suspected ACS. Data were collected and hs-cTnT measured on arrival. The primary outcome was ACS, defined as prevalent acute myocardial infarction (AMI) or incident death, AMI or coronary revascularisation within 30 days. T-MACS was built in one cohort (derivation set) and validated in three external cohorts (validation set).
Results At the ‘rule out’ threshold, in the derivation set (n=703), T-MACS had 99.3% (95% CI 97.3% to 99.9%) negative predictive value (NPV) and 98.7% (95.3%–99.8%) sensitivity for ACS, ‘ruling out’ 37.7% patients (specificity 47.6%, positive predictive value (PPV) 34.0%). In the validation set (n=1459), T-MACS had 99.3% (98.3%–99.8%) NPV and 98.1% (95.2%–99.5%) sensitivity, ‘ruling out’ 40.4% (n=590) patients (specificity 47.0%, PPV 23.9%). T-MACS would ‘rule in’ 10.1% and 4.7% patients in the respective sets, of which 100.0% and 91.3% had ACS. C-statistics for the original and refined rules were similar (T-MACS 0.91 vs MACS 0.90 on validation).
Conclusions T-MACS could ‘rule out’ ACS in 40% of patients, while ‘ruling in’ 5% at highest risk using a single hs-cTnT measurement on arrival. As a clinical decision aid, T-MACS could therefore help to conserve healthcare resources.
- acute myocardial infarct
- diagnosis
- cardiac care, diagnosis
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Twitter Follow Richard Body at @richardbody and Edward Carlton at @eddcarlton
Contributors All authors have contributed to this manuscript and fulfil the criteria for authorship as set out by the International Committee of Medical Journal Editors (ICMJE).
Funding The initial derivation study at Central Manchester University Hospitals NHS Foundation Trust was sponsored by and funded by a research grant from Central Manchester University Hospitals NHS Foundation Trust. The study undertaken at Stockport NHS Foundation Trust was funded by a grant from the UK Royal College of Emergency Medicine, and was supported by: (a) fellowship funding (an Academic Clinical Lectureship for the first author) from the UK National Institute for Health Research (NIHR); (b) by the NIHR Clinical Research Network (UK CRN 8376) and (c) reagents donated for the purposes of the research by Roche Diagnostics. The study was sponsored by Stockport NHS Foundation Trust. The validation study undertaken at Central Manchester University Hospitals NHS Foundation Trust received no external funding and was sponsored by Central Manchester University Hospitals NHS Foundation Trust. The validation study at Poole Hospital NHS Foundation Trust was funded by the Royal College of Emergency Medicine and was sponsored by Poole Hospital NHS Foundation Trust. This work was supported by the University of Manchester's Health eResearch Centre funded by the Medical Research Council grant MR/K06665/1. Except for the sponsors providing the required monitoring and governance checks, the sponsors and funders of this work played no role in the design and conduct of the study; the data collection; analysis; decision to publish or preparation of the manuscript.
Disclaimer This article/paper/report presents independent research funded by the National Institute for Health Research (NIHR). The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.
Competing interests Roche Diagnostics donated reagents without charge for the purposes of this analysis. The authors also declare the following interests: RB, SC, GM and KM-J have undertaken research involving donation of reagents without charge by Roche Diagnostics, Abbott Laboratories, Alere and Randox Laboratories. RB has accepted the provision of economy class travel and accommodation to present findings relating to separate analyses from the derivation study at two Roche Diagnostics-sponsored conferences. RB, GB and PSL report that they have undertaken research involving donation of reagents without charge by Roche Diagnostics and Siemens. RB and PSL have accepted travel and accommodation to present at a scientific session and a symposium (respectively) sponsored by Randox Laboratories. EC declares that his institution received funding from Abbott Laboratories to support the research study. KG declares that his institution has received funding from AstraZeneca for unrelated research. IB declared that his institution has received funding from GSK and MSD for unrelated research.
Patient consent Obtained.
Ethics approval NHS Research Ethics Committee (several).
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement For further information about the data presented in this manuscript or about the availability of T-MACS rule calculators, please contact the corresponding author, Richard Body.
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