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HE-MACS ACS probability

HE-MACS

Compute the Alghamdi 2019 History and Electrocardiogram-only Manchester Acute Coronary Syndromes (HE-MACS) logistic probability of ACS from age, sex, and caller-assigned observed sweating, acute ECG ischaemia, right-arm or shoulder radiation, vomiting, hypotension (SBP <100 mm Hg), and current tobacco smoking.

LIVE $0.005 USDC GET /api/calc/he_macs

Markdown: /docs/he-macs.md · Canonical: https://magentlab.com/docs/he-macs

Not a medical device. Not a diagnosis, dose, or listing recommendation.

What it computes

Compute the Alghamdi 2019 History and Electrocardiogram-only Manchester Acute Coronary Syndromes (HE-MACS) logistic probability of ACS from age, sex, and caller-assigned observed sweating, acute ECG ischaemia, right-arm or shoulder radiation, vomiting, hypotension (SBP <100 mm Hg), and current tobacco smoking.

When to use

When an agent already has those Alghamdi 2019 predictors as assigned by the caller and needs the published HE-MACS probability. magent does not interpret an ECG or take a history. Not a diagnosis, discharge protocol, MACS (Body 2014 biomarkers), or T-MACS.

When not to use

  • Not a medical device. Not a diagnosis of ACS.
  • sweating_observed, acute_ecg_ischaemia, pain_radiation_right_arm_or_shoulder, vomiting, hypotension, and current_smoker are caller-assigned. magent does not interpret ECG or take a history.
  • Age 18–100 years is an implementation clamp. Age enters as a continuous linear predictor (g).
  • Alghamdi 2019 Table 2 printed HE-MACS coefficients only. Not MACS (Body 2014 biomarkers). Not T-MACS.
  • Four-group ROC thresholds are in that paper's supplement and are not restated here.
  • This tool returns the logistic probability only. It is not a discharge, observation, or rule-out protocol.

Formula

p = 1/(1+e^(-λ)); λ = 1.426*a + 1.838*b + 0.734*c + 0.996*d + 1.353*e + 0.675*f + 0.024*g + 0.462*h - 4.416; a sweating observed 0/1; b acute ECG ischaemia 0/1; c pain radiating to right arm or shoulder 0/1; d vomiting associated with pain 0/1; e systolic BP <100 mmHg 0/1; f current tobacco smoker 0/1; g age in years (continuous); h male sex 1, female 0 (Alghamdi 2019 Table 2 printed values)

Citation

Title
Enhanced triage for patients with suspected cardiac chest pain: the History and Electrocardiogram-only Manchester Acute Coronary Syndromes decision aid
Authors
Alghamdi A, Howard L, Reynard C, et al.
Source
Eur J Emerg Med. 2019;26(5):356-361
DOI
10.1097/MEJ.0000000000000575

Worked example

Age 40, female, all six flags false

Given: acute_ecg_ischaemia=falseage=40current_smoker=falsehypotension=falsepain_radiation_right_arm_or_shoulder=falsesex=femalesweating_observed=falsevomiting=false

  1. a=b=c=d=e=f=0; g=40; h=0
  2. λ = 0.024×40 - 4.416 = -3.456
  3. p = 1/(1+e^3.456) = 0.0306

Also searched as

  • HE-MACS
  • History and Electrocardiogram-only MACS
  • Alghamdi HE-MACS
  • HE MACS decision aid
  • ECG-only Manchester ACS
  • HE-MACS chest pain
  • History ECG MACS

Try

Opens the live endpoint. Unpaid browser requests show the paywall; agents should send Accept: application/json.

/api/calc/he_macs?age=40&sex=female&sweating_observed=false&acute_ecg_ischaemia=false&pain_radiation_right_arm_or_shoulder=false&vomiting=false&hypotension=false&current_smoker=false

Full URL: https://api.magentlab.com/api/calc/he_macs?age=40&sex=female&sweating_observed=false&acute_ecg_ischaemia=false&pain_radiation_right_arm_or_shoulder=false&vomiting=false&hypotension=false&current_smoker=false

Call

Expect HTTP 402 until you retry with PAYMENT-SIGNATURE. Incomplete query params return HTTP 400 before any quote or charge. 

curl -i -H "Accept: application/json" "https://api.magentlab.com/api/calc/he_macs?age=40&sex=female&sweating_observed=false&acute_ecg_ischaemia=false&pain_radiation_right_arm_or_shoulder=false&vomiting=false&hypotension=false&current_smoker=false"

Parameters

Name Type Required Description
age number required Age in years as a continuous linear predictor (g; 18-100, implementation clamp). Alghamdi 2019 Table 2. magent does not read an identity document.
sex string required · female, male Sex used as h in Alghamdi 2019 Table 2 (male = 1, female = 0). male or female, case-insensitive. magent does not examine the patient.
sweating_observed boolean required Sweating observed by the treating clinician as assigned by the caller (a; 1 if true, 0 if false). true or false. magent does not examine the patient.
acute_ecg_ischaemia boolean required Caller-assigned acute ECG ischaemia as used in Alghamdi 2019 (b): ST-deviation or abnormal T inversion (1 if true, 0 if false). magent does not interpret an ECG.
pain_radiation_right_arm_or_shoulder boolean required Pain radiating to the right arm or shoulder as assigned by the caller (c; Alghamdi 2019). true or false. magent does not take a pain history.
vomiting boolean required Vomiting associated with the pain as assigned by the caller (d; Alghamdi 2019). true or false.
hypotension boolean required Hypotension as assigned by the caller (e): systolic BP <100 mm Hg (Alghamdi 2019, dichotomised as in that paper). true or false.
current_smoker boolean required Current tobacco smoker as assigned by the caller (f; Alghamdi 2019). true or false. magent does not take a smoking history.

Bulk (POST)

POST the same path with a JSON items array. The first item is the GET unit; each additional item is $0.002. Invalid items return HTTP 400 before settlement.

POST /api/calc/he_macs Max 25 unit_amount + extra_item_amount * (n - 1) extra $0.002 PREVIEW

  • 1 to 25 items. Each item uses the same keys as the GET query parameters.
  • POST of 1 item costs the same as GET. Lists longer than 25: chunk into multiple POSTs. Extra items still execute; do not pad dummy rows.
  • The first invalid item fails the whole request (index in the 400 JSON). You are not charged.
  • HTTP 200 is {count, path, items}. Each items[i] is the GET 200 body for that row.
  • Catalog misses (empty matches, found=false) stay paid 200s inside that slot.
  • x402 resource URL is this path plus n and body_sha256. Browsers that prefer text/html get the same paywall as GET; Pay retries POST with the same items.

Example request (fixture)

{
  "items": [
    {
      "acute_ecg_ischaemia": "false",
      "age": "40",
      "current_smoker": "false",
      "hypotension": "false",
      "pain_radiation_right_arm_or_shoulder": "false",
      "sex": "female",
      "sweating_observed": "false",
      "vomiting": "false"
    },
    {
      "acute_ecg_ischaemia": "false",
      "age": "40",
      "current_smoker": "false",
      "hypotension": "false",
      "pain_radiation_right_arm_or_shoulder": "false",
      "sex": "female",
      "sweating_observed": "false",
      "vomiting": "false"
    }
  ]
}

Open bulk paywall →

Opens a two-item fixture on the API host. Unpaid browsers get the same MetaMask paywall as GET; Pay retries POST with those items.

Example 200 (fixture)

{
  "count": 2,
  "path": "/api/calc/he_macs",
  "items": [
    {
      "age": 40.0,
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Alghamdi A, Howard L, Reynard C, et al.",
        "doi": "10.1097/MEJ.0000000000000575",
        "id": "alghamdi-2019",
        "pmid": "30289775",
        "source": "Eur J Emerg Med. 2019;26(5):356-361",
        "title": "Enhanced triage for patients with suspected cardiac chest pain: the History and Electrocardiogram-only Manchester Acute Coronary Syndromes decision aid"
      },
      "formula": "he_macs",
      "formula_expression": "p = 1/(1+e^(-λ)); λ = 1.426*a + 1.838*b + 0.734*c + 0.996*d + 1.353*e + 0.675*f + 0.024*g + 0.462*h - 4.416; a sweating observed 0/1; b acute ECG ischaemia 0/1; c pain radiating to right arm or shoulder 0/1; d vomiting associated with pain 0/1; e systolic BP <100 mmHg 0/1; f current tobacco smoker 0/1; g age in years (continuous); h male sex 1, female 0 (Alghamdi 2019 Table 2 printed values)",
      "sex": "female",
      "vomiting": false,
      "hypotension": false,
      "linear_predictor": -3.456,
      "probability": 0.0306,
      "current_smoker": false,
      "acute_ecg_ischaemia": false,
      "pain_radiation_right_arm_or_shoulder": false,
      "sweating_observed": false
    },
    {
      "age": 40.0,
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Alghamdi A, Howard L, Reynard C, et al.",
        "doi": "10.1097/MEJ.0000000000000575",
        "id": "alghamdi-2019",
        "pmid": "30289775",
        "source": "Eur J Emerg Med. 2019;26(5):356-361",
        "title": "Enhanced triage for patients with suspected cardiac chest pain: the History and Electrocardiogram-only Manchester Acute Coronary Syndromes decision aid"
      },
      "formula": "he_macs",
      "formula_expression": "p = 1/(1+e^(-λ)); λ = 1.426*a + 1.838*b + 0.734*c + 0.996*d + 1.353*e + 0.675*f + 0.024*g + 0.462*h - 4.416; a sweating observed 0/1; b acute ECG ischaemia 0/1; c pain radiating to right arm or shoulder 0/1; d vomiting associated with pain 0/1; e systolic BP <100 mmHg 0/1; f current tobacco smoker 0/1; g age in years (continuous); h male sex 1, female 0 (Alghamdi 2019 Table 2 printed values)",
      "sex": "female",
      "vomiting": false,
      "hypotension": false,
      "linear_predictor": -3.456,
      "probability": 0.0306,
      "current_smoker": false,
      "acute_ecg_ischaemia": false,
      "pain_radiation_right_arm_or_shoulder": false,
      "sweating_observed": false
    }
  ]
}

Response

Field Type Description
formula string he_macs
formula_expression string Alghamdi 2019 Table 2 printed HE-MACS logistic expression
age number Age in years used as g
sex string female or male used as h
sweating_observed boolean Caller-assigned observed sweating used as a
acute_ecg_ischaemia boolean Caller-assigned acute ECG ischaemia used as b
pain_radiation_right_arm_or_shoulder boolean Caller-assigned right-arm or shoulder radiation used as c
vomiting boolean Caller-assigned vomiting used as d
hypotension boolean Caller-assigned hypotension (SBP <100 mm Hg) used as e
current_smoker boolean Caller-assigned current tobacco smoking used as f
linear_predictor number Alghamdi 2019 Table 2 λ from the printed coefficients, 4 decimals
probability number p = 1/(1+e^(-λ)) on 0-1, 4 decimals. Probability only; no risk band.
citation object Alghamdi 2019 Eur J Emerg Med citation
disclaimer string Not-a-device notice

Example JSON

Machine form of the same example. Frozen fixture. Not a live lookup. 

{
  "age": 40.0,
  "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
  "citation": {
    "authors": "Alghamdi A, Howard L, Reynard C, et al.",
    "doi": "10.1097/MEJ.0000000000000575",
    "id": "alghamdi-2019",
    "pmid": "30289775",
    "source": "Eur J Emerg Med. 2019;26(5):356-361",
    "title": "Enhanced triage for patients with suspected cardiac chest pain: the History and Electrocardiogram-only Manchester Acute Coronary Syndromes decision aid"
  },
  "formula": "he_macs",
  "formula_expression": "p = 1/(1+e^(-λ)); λ = 1.426*a + 1.838*b + 0.734*c + 0.996*d + 1.353*e + 0.675*f + 0.024*g + 0.462*h - 4.416; a sweating observed 0/1; b acute ECG ischaemia 0/1; c pain radiating to right arm or shoulder 0/1; d vomiting associated with pain 0/1; e systolic BP <100 mmHg 0/1; f current tobacco smoker 0/1; g age in years (continuous); h male sex 1, female 0 (Alghamdi 2019 Table 2 printed values)",
  "sex": "female",
  "vomiting": false,
  "hypotension": false,
  "linear_predictor": -3.456,
  "probability": 0.0306,
  "current_smoker": false,
  "acute_ecg_ischaemia": false,
  "pain_radiation_right_arm_or_shoulder": false,
  "sweating_observed": false
}

Client errors (HTTP 400)

Invalid params return 400 without charge. Shared HTTP 402 and 503 meanings: Payments.

HTTP Code When
400 invalid_he_macs HE-MACS inputs must match Alghamdi 2019 age, sex, and the six dichotomous history/ECG predictors from that paper. Returned before settlement; you are not charged.
400 invalid_items POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
400 invalid_item_count items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
400 invalid_item each items entry must be a JSON object Returned before settlement; you are not charged.

Related tools

  • MACS — Compute the Body 2014 Manchester Acute Coronary Syndromes (MACS) logistic probability of ACS from caller-assigned ECG ischaemia, worsening angina, right-arm or shoulder radiation, vomiting, observed sweating, hypotension, Roche Elecsys hs-cTnT in ng/L, and ELISA heart-type fatty acid-binding protein in ng/mL.
  • T-MACS — Compute the Body 2016 Troponin-only Manchester Acute Coronary Syndromes (T-MACS) logistic probability of ACS from caller-assigned ECG ischaemia, worsening angina, right-arm or shoulder radiation, vomiting, observed sweating, hypotension, and Roche Elecsys hs-cTnT in ng/L.
  • HEART score — Compute the HEART score as age points plus caller-assigned history, ECG, risk factors, and troponin (each 0-2).

Payment

Unpaid requests return HTTP 402 even if query parameters or POST items are missing or invalid, so CDP and agents can index the path. After a PAYMENT-SIGNATURE, invalid params return HTTP 400 JSON before settlement. magent does not charge. Fix the params, then request a new 402 quote for that complete URL. Catalog misses (empty matches, found=false) are valid paid 200s. Unpaid valid requests return HTTP 402 with a base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote: retry the same PAYMENT-SIGNATURE. Full handshake and shared payment errors: Payments. Stdio MCP: /docs/mcp.

Guarantees

  • HTTP 402 is unpaid, including a missing query. After PAYMENT-SIGNATURE, invalid parameters return HTTP 400 before settlement. You are not charged. HTTP 402 never includes the tool JSON.
  • exact: settlement finishes before the tool (paymentFlow upfront). batch-settlement: verify/deposit before the tool; chargedCumulativeAmount commits after HTTP 2xx. Uncertain or failed settlement fails closed (HTTP 503). Retry the same PAYMENT-SIGNATURE.
  • HTTP 402 is unpaid only. Do not sign a second authorization because of a 503.
  • Execution is timeout-bounded and concurrency-capped.
  • Calculator inputs are stored encrypted for allowlisted operators (Magent Console). They are not in public logs, SSH lookups, catalog, or rollups. Request logs store path without query.