T-MACS Calculator (Troponin-only Manchester Acute Coronary Syndromes)
T-MACS evaluates individual patient’s risk of acute coronary syndrome for 30 days based on hs-cTnT concentration and simple observations.
Refer to the text below the calculator for the T-MACS formula and more information about the original study and statistic results in derivation and validation cohorts.
T-MACS can be used to rule out ACS in very low risk patients and to rule in ACS in high risk patients without invasive and serial blood tests or lengthy hospital stays.
T-MACS only requires hs-cTnT concentration on arrival (from blood test) along with clinical observation of symptoms of patients presenting to the emergency department with suspected cardiac chest pain (see formula here).
ACS was defined as prevalent acute myocardial infarction (AMI) or incident death, AMI or coronary revascularisation within 30 days.
- Approximately 40% can be stratified as very low risk with <1% probability of ACS.
- Approximately 5% can be stratified as high risk of ACS.
It is important to note that elevated low-specificity troponin values are not exclusive to ACS in high-risk patients so differential diagnosis may be required.
As a shortcut, if all components of the T-MACS are negative, it is very likely that ACS can be ruled out without having to calculate the probability.
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Steps on how to print your input & results:
1. Fill in the calculator/tool with your values and/or your answer choices and press Calculate.
2. Then you can click on the Print button to open a PDF in a separate window with the inputs and results. You can further save the PDF or print it.
Please note that once you have closed the PDF you need to click on the Calculate button before you try opening it again, otherwise the input and/or results may not appear in the pdf.
About the T-MACS decision aid
The Troponin-only Manchester Acute Coronary Syndromes (T-MACS) Decision Aid can be used to rule out ACS, stratify individual patient’s risk of ACS or 30-day risk of major adverse cardiac events (MACE) in 4 risk categories, each with their own care guideline.
T-MACS only requires hs-cTnT concentration on arrival (from a single blood test, not serial measurements) along with clinical observation of symptoms of patients presenting to the emergency department with suspected cardiac chest pain.
T-MACS consists of the following 6 items:
- EKG ischemia (as determined by treating clinician)
- Worsening or crescendo angina
- Pain radiating to right arm or shoulder
- Pain associated with vomiting
- Sweating observed (as observed by treating clinician)
- Hypotension (sBP <100 mmHG on arrival to ED)
- hs-cTnT concentration on arrival, either expressed in ng/L or μg/L
Probability of acute coronary syndrome in 30 days is then calculated through the below formula:
Where the letters are given either values of 1 (if present) or 0 (if absent) and hs-cTnT concentration on arrival is expressed in ng/L:
- E: EKG ischemia (as determined by treating clinician);
- A: Worsening or crescendo angina;
- P: Pain radiating to right arm or shoulder;
- V: Pain associated with vomiting;
- S: Sweating observed (as observed by treating clinician);
- H: Hypotension (sBP <100 mmHG on arrival to ED);
- T: hs-cTnT concentration on arrival expressed in ng/L.
The probability can further be associated to a risk group with specific advice:
| 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. |
With respect to the use of low-specificity troponin blood tests, it is important to note that elevated values are not exclusive to ACS in high-risk patients but may have other cardiac and non-cardiac aetiologies, so differential diagnosis may be required.
Potential cardiac causes of elevated troponin include acute and chronic heart failure, myocarditis, cardioversion, endocarditis, hypertrophic cardiomyopathy, tachy - or bradyarrhythmia, heart block or pericarditis. Non-cardiac causes include pulmonary embolism, stroke, sepsis, renal failure or infiltrative diseases.
Other similar decision aids for stratifying risk of ACS include the HEART Score and the Emergency Department Assessment of Chest Pain Score (EDACS).
About the original study
The 2017 study by Body et al. was aimed at refining and validating the original Manchester Acute Coronary Syndromes model (MACS), by removing the need for the biomarker heart-type fatty acid binding protein (H-FABP), this leaving just the measurement of the high sensitivity cardiac troponin T (hs-cTnT) at admission.
Data were collected from four prospective diagnostic cohort studies (1 derivation set of 703 patients and 3 validation sets, totalling 1,459 patients) presenting to the ED with suspected ACS, where ACS was defined as prevalent acute myocardial infarction (AMI) or incident death, AMI or coronary revascularisation within 30 days. Follow up consisted of standard troponin test >12hrs after peak symptoms (or at least 6hrs after ED visit) and patients were contacted after 30 days.
Here is a summary of the statistic results on the derivation and validation sets:
| Statistic | Derivation set | Validation sets |
| negative predictive value (NPV) | 99.3% (95% CI 97.3% to 99.9%) | 99.3% (98.3%-99.8%) |
| sensitivity for ACS | 98.7% (95.3%-99.8%) | 98.1% (95.2%-99.5%) |
| specificity | 47.6% | 47.0% |
| positive predictive value (PPV) | 34.0% | 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.
T-MACS was found to be a useful clinical decision aid that calculates each individual patient’s risk of ACS based on simple observations and a single blood test at time of arrival in the emergency department. By assigning a risk group to the patient, the clinician can then follow the appropriate course of action.
At Manchester Royal Infirmary, United Kingdom, the application of T-MACS was found to be superior to NICE guidelines. It has the potential to improve quality of care and reduce clinical costs. Two-third of patients are in average provided with care in an ambulatory setting (and most discharged the same day) as opposed to a two-day average stay by following routine care pathways.
References
Original reference
Body R, Carlton E, Sperrin M, et al. Troponin-only Manchester Acute Coronary Syndromes (T-MACS) decision aid: single biomarker re-derivation and external validation in three cohorts. Emerg Med J. 2017
Validation
Greenslade JH, Nayer R, Parsonage W, et al. Validating the Manchester Acute Coronary Syndromes (MACS) and Troponin-only Manchester Acute Coronary Syndromes (T-MACS) rules for the prediction of acute myocardial infarction in patients presenting to the emergency department with chest pain. Emerg Med J. 2017
Specialty: Cardiology
System: Cardiovascular
Objective: Risk Stratification
Type: Decision Aid
No. Of Items: 7
Year Of Study: 2017
Abbreviation: T-MACS
Article By: Denise Nedea
Published On: July 3, 2023 · 05:20 PM
Last Checked: July 3, 2023
Next Review: July 3, 2028