History and Electrocardiogram-only Manchester Acute Coronary Syndromes (HE-MACS)

HE-MACS Calculator

Sweating Observed by Clinician

Vomiting

Systolic BP < 100 mmHg

Worsening / Crescendo Angina

ECG Ischemia (ST changes or T-wave inversion)

Pain Radiating to Right Arm or Shoulder

Hypoperfusion by Exam

Estimated MI Probability: –

Awaiting input

Default assumes No for un-set fields.

Stratifies ACS risk with history and EKG only (not yet externally validated).

Why Use

May be a useful adjunct to clinical judgment, especially in resource-limited settings where biomarkers are not available. Accurate risk stratification of patients prior to biomarker information may enhance triage and help guide disposition.

When to Use

Patients ≥18 years old presenting with suspected cardiac chest pain (symptoms within the last 24 hours).

Formula

Probability of ACS = 1 / (1 + e x ), where x = - [(1.426 x sweating) + (1.838 x EKG) + (0.734 x pain) + (0.996 x vomiting) + (1.353 x systolic BP) + (0.675 x tobacco) + (0.024 x age) + (0.462 x sex) − 4.416] and the variables are as follows: Variable Points Age , years Continuous Sex Female 0 Male 1 Sweating observed No 0 Yes 1 Acute EKG ischemia No 0 Yes 1 Pain radiating to the right arm or shoulder No 0 Yes 1 Vomiting associated with pain No 0 Yes 1 Systolic BP <100 mmHg No 0 Yes 1 Current tobacco smoker No 0 Yes 1

Pearls / Pitfalls

30-day major adverse cardiac event (MACE) was defined as acute MI, all-cause death, or coronary revascularization. Not yet prospectively validated (externally validated in a single cohort retrospectively; see Evidence for details). Validated in emergency settings and not yet validated in paramedic, primary care, or triage-specific settings. Point to keep in mind: Note that the authors chose the cutoff for ACS probability in the “very low risk” group (<4%) as determined by receiver operator curve ( ROC ) analysis to achieve 100% sensitivity (i.e., to miss no cases of ACS or 30-day MACE), not necessarily as a reasonable clinical risk threshold for rule-out.

Critical Actions

HE-MACS is a decision aid and not a definitive test that is designed to assist in the risk stratification of patients with chest pain. Clinical judgment should always be used. Where all the HE-MACS decision aid components are negative and a “very low” risk of ACS or 30-day MACE is identified, ACS is unlikely and discharge without cardiac biomarkers may be considered, with caution.

Advice

In patients who are “very low” risk, ACS is unlikely. Consider discharge without cardiac biomarkers, with caution, and consider further investigation in an ambulatory setting. “Very low” risk was <4.0% risk of ACS or MACE in 30 days, which was selected by the authors to achieve 100% sensitivity in the derivation cohort, and was subsequently found to be 99.5% sensitive (95% CI 97.1-100) in validation cohorts. In patients who are not “very low” risk, further workup is recommended.

More Information

Interpretation: Risk of ACS or MACE in 30 days Risk group <4.0% Very low 4.0-6.9% Low 7.0-49.9% Moderate ≥50.0% High