# ACCF/AHA heart-failure stages

ACCF/AHA HF stages

Status: LIVE
Price: $0.005 USDC
`GET /api/calc/acc_aha_hf`
HTML: https://magentlab.com/docs/acc-aha-hf
Markdown: https://magentlab.com/docs/acc-aha-hf.md

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

## What it computes

Apply the 2013 ACCF/AHA heart-failure stages (Yancy) from caller-assigned high-risk, structural heart disease, prior or current HF symptoms, and refractory specialized-care flags. Returns hf_stage A, B, C, D, or not_staged.

## When to use

When an agent already has the four published stage assignments as booleans and needs the 2013 ACCF/AHA stage. magent does not examine the patient or read an echocardiogram. Not NYHA functional class.

## When not to use

- Not a medical device and not a diagnosis of heart failure.
- magent does not examine the patient or read an echocardiogram. The four flags are caller-assigned.
- Stages are progressive and inviolate (Yancy 2013). D if refractory specialized care; else C if structural disease and prior or current symptoms; else B if structural disease without those symptoms; else A if high risk without structural disease or symptoms; else not_staged.
- Not NYHA functional class. This tool does not assign NYHA I-IV.

## Formula

```
hf_stage D if refractory_hf_specialized; else C if structural_heart_disease and hf_symptoms_prior_or_current; else B if structural_heart_disease and not hf_symptoms_prior_or_current; else A if high_risk_for_hf and not structural_heart_disease and not hf_symptoms_prior_or_current; else not_staged (Yancy 2013 ACCF/AHA stages, progressive/inviolate). Not NYHA class
```

## Citation

[2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines](https://doi.org/10.1161/CIR.0b013e31829e8776)
Yancy CW, Jessup M, Bozkurt B, Butler J, Casey DE Jr, Drazner MH, Fonarow GC, Geraci SA, Horwich T, Januzzi JL, Johnson MR, Kasper EK, Levy WC, Masoudi FA, McBride PE, McMurray JJV, Mitchell JE, Peterson PN, Riegel B, Sam F, Stevenson LW, Tang WHW, Tsai EJ, Wilkoff BL
Circulation. 2013;128(16):e240-e327
DOI: [10.1161/CIR.0b013e31829e8776](https://doi.org/10.1161/CIR.0b013e31829e8776)

## Worked example

### No high risk, no structural disease, no symptoms

Given: `hf_symptoms_prior_or_current=false, high_risk_for_hf=false, refractory_hf_specialized=false, structural_heart_disease=false`

1. refractory_hf_specialized false → not D
2. structural_heart_disease false → not C and not B
3. high_risk_for_hf false → not A
4. hf_stage is not_staged


## Also searched as

- ACCF/AHA HF stages
- ACC/AHA heart failure stages
- Yancy 2013 HF stages
- heart failure stage A B C D
- ACCF AHA stage C
- ACCF AHA stage D refractory
- 2013 heart failure guideline stages
- structural heart disease HF stage

## Parameters

- `high_risk_for_hf` (boolean, required): High risk for HF without structural heart disease or HF symptoms (Yancy 2013 stage A assignment). true or false as assigned by the caller. magent does not examine the patient.
- `structural_heart_disease` (boolean, required): Structural heart disease as assigned by the caller (Yancy 2013 stage B or C). true or false. magent does not read an echocardiogram.
- `hf_symptoms_prior_or_current` (boolean, required): Prior or current symptoms of HF as assigned by the caller (Yancy 2013 stage C). true or false. magent does not examine the patient.
- `refractory_hf_specialized` (boolean, required): Refractory HF requiring specialized interventions as assigned by the caller (Yancy 2013 stage D). true or false. magent does not examine the patient.

## 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.

Method: `POST /api/calc/acc_aha_hf`
Max items: 25
Price: unit_amount + extra_item_amount * (n - 1) (unit 5000 atomic, extra 2000 atomic)
Status: 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:

```json
{
  "items": [
    {
      "hf_symptoms_prior_or_current": "false",
      "high_risk_for_hf": "false",
      "refractory_hf_specialized": "false",
      "structural_heart_disease": "false"
    },
    {
      "hf_symptoms_prior_or_current": "false",
      "high_risk_for_hf": "false",
      "refractory_hf_specialized": "false",
      "structural_heart_disease": "false"
    }
  ]
}
```

Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/acc-aha-hf

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/acc_aha_hf",
  "items": [
    {
      "components": [
        {
          "factor": "high_risk_for_hf",
          "met": false
        },
        {
          "factor": "structural_heart_disease",
          "met": false
        },
        {
          "factor": "hf_symptoms_prior_or_current",
          "met": false
        },
        {
          "factor": "refractory_hf_specialized",
          "met": false
        }
      ],
      "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": "Yancy CW, Jessup M, Bozkurt B, Butler J, Casey DE Jr, Drazner MH, Fonarow GC, Geraci SA, Horwich T, Januzzi JL, Johnson MR, Kasper EK, Levy WC, Masoudi FA, McBride PE, McMurray JJV, Mitchell JE, Peterson PN, Riegel B, Sam F, Stevenson LW, Tang WHW, Tsai EJ, Wilkoff BL",
        "doi": "10.1161/CIR.0b013e31829e8776",
        "id": "yancy-2013",
        "pmid": "23741058",
        "source": "Circulation. 2013;128(16):e240-e327",
        "title": "2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines"
      },
      "formula": "acc_aha_hf",
      "formula_expression": "hf_stage D if refractory_hf_specialized; else C if structural_heart_disease and hf_symptoms_prior_or_current; else B if structural_heart_disease and not hf_symptoms_prior_or_current; else A if high_risk_for_hf and not structural_heart_disease and not hf_symptoms_prior_or_current; else not_staged (Yancy 2013 ACCF/AHA stages, progressive/inviolate). Not NYHA class",
      "hf_stage": "not_staged",
      "hf_symptoms_prior_or_current": false,
      "high_risk_for_hf": false,
      "refractory_hf_specialized": false,
      "structural_heart_disease": false
    },
    {
      "components": [
        {
          "factor": "high_risk_for_hf",
          "met": false
        },
        {
          "factor": "structural_heart_disease",
          "met": false
        },
        {
          "factor": "hf_symptoms_prior_or_current",
          "met": false
        },
        {
          "factor": "refractory_hf_specialized",
          "met": false
        }
      ],
      "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": "Yancy CW, Jessup M, Bozkurt B, Butler J, Casey DE Jr, Drazner MH, Fonarow GC, Geraci SA, Horwich T, Januzzi JL, Johnson MR, Kasper EK, Levy WC, Masoudi FA, McBride PE, McMurray JJV, Mitchell JE, Peterson PN, Riegel B, Sam F, Stevenson LW, Tang WHW, Tsai EJ, Wilkoff BL",
        "doi": "10.1161/CIR.0b013e31829e8776",
        "id": "yancy-2013",
        "pmid": "23741058",
        "source": "Circulation. 2013;128(16):e240-e327",
        "title": "2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines"
      },
      "formula": "acc_aha_hf",
      "formula_expression": "hf_stage D if refractory_hf_specialized; else C if structural_heart_disease and hf_symptoms_prior_or_current; else B if structural_heart_disease and not hf_symptoms_prior_or_current; else A if high_risk_for_hf and not structural_heart_disease and not hf_symptoms_prior_or_current; else not_staged (Yancy 2013 ACCF/AHA stages, progressive/inviolate). Not NYHA class",
      "hf_stage": "not_staged",
      "hf_symptoms_prior_or_current": false,
      "high_risk_for_hf": false,
      "refractory_hf_specialized": false,
      "structural_heart_disease": false
    }
  ]
}
```

## Response fields

- `formula` (string): acc_aha_hf
- `formula_expression` (string): Published Yancy 2013 ACCF/AHA stage assignment (progressive/inviolate)
- `high_risk_for_hf` (boolean): Echo of the caller-assigned high-risk-for-HF flag
- `structural_heart_disease` (boolean): Echo of the caller-assigned structural-heart-disease flag
- `hf_symptoms_prior_or_current` (boolean): Echo of the caller-assigned prior-or-current HF symptoms flag
- `refractory_hf_specialized` (boolean): Echo of the caller-assigned refractory specialized-care flag
- `hf_stage` (string): ACCF/AHA stage A, B, C, or D, or not_staged when no high risk, no structural disease, and no symptoms. Not NYHA class. Not a diagnosis.
- `components` (array): Rows for the four caller flags with factor and met
- `citation` (object): Yancy 2013 Circulation citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "components": [
    {
      "factor": "high_risk_for_hf",
      "met": false
    },
    {
      "factor": "structural_heart_disease",
      "met": false
    },
    {
      "factor": "hf_symptoms_prior_or_current",
      "met": false
    },
    {
      "factor": "refractory_hf_specialized",
      "met": false
    }
  ],
  "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": "Yancy CW, Jessup M, Bozkurt B, Butler J, Casey DE Jr, Drazner MH, Fonarow GC, Geraci SA, Horwich T, Januzzi JL, Johnson MR, Kasper EK, Levy WC, Masoudi FA, McBride PE, McMurray JJV, Mitchell JE, Peterson PN, Riegel B, Sam F, Stevenson LW, Tang WHW, Tsai EJ, Wilkoff BL",
    "doi": "10.1161/CIR.0b013e31829e8776",
    "id": "yancy-2013",
    "pmid": "23741058",
    "source": "Circulation. 2013;128(16):e240-e327",
    "title": "2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines"
  },
  "formula": "acc_aha_hf",
  "formula_expression": "hf_stage D if refractory_hf_specialized; else C if structural_heart_disease and hf_symptoms_prior_or_current; else B if structural_heart_disease and not hf_symptoms_prior_or_current; else A if high_risk_for_hf and not structural_heart_disease and not hf_symptoms_prior_or_current; else not_staged (Yancy 2013 ACCF/AHA stages, progressive/inviolate). Not NYHA class",
  "hf_stage": "not_staged",
  "hf_symptoms_prior_or_current": false,
  "high_risk_for_hf": false,
  "refractory_hf_specialized": false,
  "structural_heart_disease": false
}
```

## Errors

- HTTP 400 `invalid_flag`: boolean clinical flags must be true or false Returned before settlement; you are not charged.
- HTTP 400 `invalid_items`: POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
- HTTP 400 `invalid_item_count`: items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
- HTTP 400 `invalid_item`: each items entry must be a JSON object Returned before settlement; you are not charged.

Shared HTTP 402 and 503: https://magentlab.com/docs/payments

## Related tools

- [NYHA](https://magentlab.com/docs/nyha) — Return the 1994 NYHA functional capacity class 1-4 from a caller-assigned integer, with the published class description.
- [Framingham HF criteria](https://magentlab.com/docs/framingham-hf) — Apply the McKee 1971 Framingham concurrent major and minor criteria and return definite or not_definite from nine major flags, seven minor flags, and the dual weight-loss flag.

## 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.

- GET the tool with Accept: application/json (do not send Accept: text/html unless you want the human paywall).
- HTTP 402 means you have not paid. Decode the base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote.
- Sign accepts[0] (exact, EIP-3009) with validBefore = now + maxTimeoutSeconds (600 seconds), or accepts[1] (batch-settlement deposit/voucher) on product GET. Ping and POST {items} stay exact. Magent retries transient facilitator 429/5xx before answering.
- Retry the same URL with PAYMENT-SIGNATURE (base64 JSON of accepted and payload). Magent attaches canonical extensions.bazaar on CDP verify/settle; echoing 402 bazaar is optional.
- Success is HTTP 200 JSON plus PAYMENT-RESPONSE. exact settles before the tool. batch-settlement verifies (and deposit-settles) before the tool and commits the charge after HTTP 2xx. HTTP 503: retry the same PAYMENT-SIGNATURE. Mint a new exact nonce only after a new HTTP 402.

- offered `exact` on eip155:8453: Fixed-price USDC on Base. The buyer authorizes the advertised amount (EIP-3009). magent settles before the tool runs (paymentFlow upfront). extra.assetTransferMethod=eip3009 extra.paymentFlow=upfront.
- offered `batch-settlement` on eip155:8453: Payment-channel vouchers claimed later in batches. Exact stays accepts[0]. Same-path POST {items} is still exact. extra.assetTransferMethod=eip3009 extra.paymentFlow=authorization.

- not offered `upto`: Not offered. Usage-based: buyer authorizes a ceiling, seller settles the actual amount after work. Reserved for a future metered tool. Not for current calculators or code search.

Same-path POST {items} is still scheme exact: one EIP-3009 authorization for GET unit plus $0.002 per extra item. That is not x402 batch-settlement (payment channels / vouchers).

Shared HTTP 402 and 503 table: https://magentlab.com/docs/payments

Stdio MCP (one process per host): https://magentlab.com/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.