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T-MACS – One and Done MI Rule-Out

July 19, 2017

T-MACS – One and Done
In the original study, they used hs-TnT and heart-type fatty acid binding protein along with clinical criteria.  Here is the original MACS decision aid:

  • A. High sensitivity cardiac troponin T (ng/L) – Continuous variable
  • B. Heart-type fatty acid binding protein (ng/mL) – Continuous
  • C. ECG ischaemia – Dichotomous variable
  • D. Sweating observed by the treating clinician – Dichotomous
  • E. Vomiting in association with the presenting symptoms – Dichotomous
  • F. Systolic BP <100 mm Hg on arrival – Dichotomous
  • G. Worsening (or crescendo) angina – Dichotomous
  • H. Pain radiating to the right arm or shoulder – Dichotomous

They reanalyzed the data with just hs-TnT, dropping the heart-fatty-protein-acid-bindy-thingy (whatever that was…).  There was a derivation and subsequent validation of this diagnostic decision aid at 3 external locations.  The primary outcome was acute coronary syndrome (ACS), “defined as prevalent acute myocardial infarction (AMI) or incident death, AMI or coronary revascularisation within 30 days.”  They found T-MACS to have 99.3% NPV and 98.1% sensitivity.  It would have allowed 40% to be ruled out with one troponin.

You have got to play around with the MDCalc version of T-MACS.  It is fascinating to change the variables and watch what happens to the risk percentage as dichotomous or hs-TnT continuous variables change.  I have to admit, my bias is to do serial troponins, which others think is a best practice as well. It depends on your comfort level with 98% sensitivity.

Spoon Feed
T-MACS is a viable rule-out (or rule-in) option to aid clinical decision making in patients with chest pain using hs-TnT (now available in the US).  Don’t miss this blog post on St. Emlyns by lead author Rick Body about this article.

Troponin-only Manchester Acute Coronary Syndromes (T-MACS) decision aid: single biomarker re-derivation and external validation in three cohorts. Emerg Med J. 2017 Jun;34(6):349-356. doi: 10.1136/emermed-2016-205983. Epub 2016 Aug 26.

Peer reviewed by Thomas Davis.

What are your thoughts?