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    Troponin-only Manchester Acute Coronary Syndromes (T-MACS) Decision Aid

    Rules out acute coronary syndrome.
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    When to Use
    Pearls/Pitfalls
    Why Use

    Patients with chest pain that may be cardiac in nature.

    • The T-MACS Decision Aid predicts acute coronary syndrome (ACS) or 30-day major adverse cardiac events (MACE) in patients with suspected cardiac chest pain.
    • 30-day MACE was defined as acute myocardial infarction (AMI), death, or coronary revascularization.
    • Uses high sensitivity cardiac troponin T (hs-cTnT), along with subjective symptoms and objective signs to risk stratify chest pain patients with suspected cardiac chest pain.
    • Uses a single hs-cTnT measurement on arrival, not serial values like other chest pain scores.
    • Inclusion and exclusion criteria differed slightly between the derivation and validation sets, e.g. chest pain within 12 vs. 24 hours of onset; age limits 16 vs. 18 vs. 25 years old.

    Point to Keep in Mind:

    • Remember, hs-cTNT is also a low-specificity troponin. While it may suggest ACS in high-risk patients, it can be elevated for many other reasons besides acute coronary syndromes. See Evidence for differential diagnoses.
    • Can essentially rule OUT ACS in very low risk patients.
    • Can essentially rule IN ACS in high risk patients.
    • Can avoid costly hospital admissions or risk of harm from invasive tests in patients predicted not to have ACS or risk of 30-day MACE.
    No
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    Yes
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    No
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    Yes
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    No
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    µg/L

    Result:

    Please fill out required fields.

    Next Steps
    Evidence
    Creator Insights

    Critical Actions

    • T-MACS is a decision aid and not a definitive test. It is designed to assist in the workup of a patient’s chest pain. Clinical judgment should always be used.
    • If all the components of the T-MACS decision aid are negative, ACS can essentially be ruled out without having to calculate the score.

    Formula

    Probability of ACS (p) = 

    where:

     

    No

    Yes

    E: EKG ischemia

    0

    1

    A: Worsening or crescendo angina

    0

    1

    R: Pain radiation to the right arm or shoulder

    0

    1

    V: Pain associated with vomiting

    0

    1

    S: Sweating observed

    0

    1

    H: Hypotension

    0

    1

    T: hs-cTnT concentration on arrival

    hs-cTnT value 


    Remember, hs-cTnT has low specificity—troponin may be elevated by a number of non-ACS etiologies, including:

    Cardiac causes

    Cardiac contusion (trauma)

    Heart failure, acute and chronic

    Tachy- or bradyarrhythmia, heart block

    Cardiac surgery

    Aortic dissection

    Apical ballooning syndrome

    Cardioversion

    Aortic valve disease

    Post-PCI

    Endomyocardial biopsy

    Hypertrophic cardiomyopathy

    Rhabdomyolysis with myocyte necrosis

    Myocarditis

    Endocarditis

    Pericarditis

    Non-cardiac causes

    PE

    Severe pulmonary HTN

    Renal failure

    Stroke, SAH

    Amyloidosis, other infiltrative diseases

    Cardiotoxic drugs

    Critical illness

    Sepsis

    Extensive burns

    Extreme exertion

       

    From Mahajan 2011.

    Facts & Figures

    Interpretation:

    Probability

    Risk

    Interpretation

    <0.02

    Very low

    ACS ruled out. Consider discharge.

    ≥0.02 and <0.05

    Low

    Consider serial troponin in ED ward, e.g. 3h troponin; consider discharge if normal.

    ≥0.05 and <0.95

    Moderate

    Serial troponin in general ward and consider stress testing and/or CT coronary angiography thereafter.

    ≥0.95

    High

    ACS ruled in. Refer to cardiology, treat for ACS.

    Evidence Appraisal

    The original derivation of the T-MACS Decision Aid was a prospective study by Body et al in the United Kingdom. The goal was to compare ability of T-MACS to the original MACS, the latter of which included both hs-cTnT and H-FABP (heart-type fatty acid binding protein) in predicting ACS or MACE.

    Patient Cohorts:

    • Derived from 703 ED patients from Manchester Royal Infirmary.
    • Validated in set of 3 cohorts: 462 from Stepping Hill Hospital, 191 from Manchester Royal Infirmary, and 806 from Poole NHS Foundation Trust.
    • Included ED patients complaining of chest pain who the clinician suspected as possibly having cardiac chest pain.
    • Caveat: Unlike patients in the other 2 validation cohorts, patients from Poole that had EKG findings of ischemia were excluded from the study.

    Follow-up:

    Standard troponin test >12 hours after peak symptoms or least 6 hours after ED presentation. Patients (or their primary care physician) were also contacted after 30 days.

    Outcomes:

    The primary outcome was diagnosis of ACS or MACE (AMI, death, coronary revascularization) in 30 days, with a secondary outcome of >50% coronary stenosis, even if no intervention was undertaken.

    Results in the derivation set:

    • 22.3% had ACS (18.5% with AMI).
    • 37.7% were labeled as very low risk for ACS (NPV 99.3%).
    • Two patients labeled as very low risk had ACS.
      • #1: hs-cTnT of 9 ng/L and non-ischemic EKG within 1 hour of symptom onset but cTnT of 2650 ng/L at 12 hours.
      • #2: Percutaneous coronary intervention (PCI) within 30 days despite normal cTnT levels.
    • 10.1% were labeled as high risk for ACS (PPV 100%).

    Results in the validation set:

    • 14.5% had ACS (11.8% with AMI).
    • 40.4% were labeled as very low risk for ACS (NPV 99.3%).
    • Four patients labeled as very low risk had ACS.
      • #1: hs-cTnT 6 ng/L on arrival, 43 ng/L at hour 6;  paroxysmal supraventricular tachycardia.
      • #2: hs-cTnT 6 ng/L on arrival, 18 ng/L at hour 6; moderate LAD stenosis on CT coronary angiography but no intervention.
      • #3: Ischemic chest pain, PCI on day 4.
      • #4: Ischemic chest pain, PCI on day 8.
    • Seven patients (1.2%) labeled as very low risk had stenosis found on angiography but did not have intervention.
    • 4.7% were labeled as high risk for ACS (PPV 84%).

    Comparing T-MACS to MACS:

    • Compared to its predecessor, MACS (which incorporated both hs-cTnT and H-FABP), T-MACS uses a lower hs-cTnT threshold without greatly sacrificing sensitivity.
    • MACS with 18.0% labeled as very low risk vs. T-MACS 40.5%.
    • Sensitivity for MACS was 100% vs. T-MACS 98.4% (p=0.25).

    Conclusion:

    • ~40% can be labeled as very low risk with <1% probability of ACS.
    • ~5% can be labeled as high risk of ACS.
    Dr. Richard Body

    About the Creator

    Richard Body, MB ChB, MRCSEd, PhD, is a professor of the Royal College of Emergency Medicine and consultant in emergency medicine at the Manchester Royal Infirmary. He earned his PhD in clinical decision rules to enable early exclusion of acute coronary syndromes. Dr. Body is the founder of the Manchester Acute Coronary Syndromes (MACS) Academic Group.

    To view Dr. Richard Body's publications, visit PubMed

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    About the Creator
    Dr. Richard Body
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