The Troponin-only Manchester Acute Coronary Syndromes (T-MACS) decision aid for rapid rule-in and rule-out of acute coronary syndromes using a contemporary point of care troponin assay
Richard Body; Malak Almashali; Niall Morris; Phil Moss; Heather Jarman; Andrew Appelboam; Richard Parris; Louisa Chan; Alison Walker; Mark Harrison; Andrea Wootten; Garry McDowellc
Objectives
The rapid turnaround time of point of care (POC) cardiac troponin (cTn) assays is highly attractive for crowded Emergency Departments (EDs). We evaluated the diagnostic accuracy of the Troponin-only Manchester Acute Coronary Syndromes (T-MACS) decision aid with a POC cTn assay.
Methods
In a prospective diagnostic accuracy study at 8 EDs, we included patients with suspected acute coronary syndromes (ACS). Blood drawn on arrival and 3 hours later was analysed for POC cTnI (i-Stat, Abbott Point of Care). The primary outcome was a diagnosis of ACS, which included both an adjudicated diagnosis of acute myocardial infarction (AMI) based on serial laboratory cTn testing and major adverse cardiac events (death, AMI or coronary revascularization) within 30 days.
Results
Of 716 patients included, 105 (14.7%) had ACS. Using serial POC cTnI concentrations over 3 hours could have ‘ruled out’ ACS in 198 (31.2%) patients with a sensitivity of 99.0% (95% CI 94.4 – 100.0%) and negative predictive value 99.5% (95% CI 96.5 – 99.9%). No AMIs were missed. T-MACS ‘ruled in’ ACS for 65 (10.4%) patients with a positive predictive value of 91.2% (95% CI 82.1 – 95.9%) and specificity 98.9% (97.6 – 99.6%).
Conclusion
With a POC cTnI assay, T-MACS could ‘rule out’ ACS for approximately one third of patients within 3 hours while ‘ruling in’ ACS for another 10%. The rapid turnaround time and portability of the POC assay make this an attractive pathway for use in crowded EDs or urgent care centres. Future work should also evaluate use in the pre-hospital environment.
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