# ACC/AHA Heart Failure Stage Calculator (Yancy 2013)

> ACC/AHA Heart Failure Stage Calculator (Yancy 2013) is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-16).

Assigns the 2013 ACCF/AHA heart failure stage (A, B, C, or D) from four boolean clinical flags provided by the caller, following the Yancy 2013 progressive staging algorithm.

## Facts

- Endpoint: GET https://api.magentlab.com/api/calc/acc_aha_hf
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/acc-aha-heart-failure-stage-calculator-yancy-2013-536665ae
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_-WpIQS9E9n_Rsfgcq4VlZ

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability acc-aha-heart-failure-stage-calculator-yancy-2013-536665ae
```

Example prompt: Stage this patient using the 2013 ACC/AHA Yancy heart failure criteria: they have structural heart disease and prior HF symptoms, but are not high risk without disease and do not require refractory specialized care.

## When to prefer this

Use this endpoint when you need a fast, deterministic mapping from four pre-assessed clinical boolean flags to a 2013 ACCF/AHA heart failure stage per Yancy. Prefer it over manual lookup tables or LLM reasoning when you need consistent, guideline-adherent staging logic in a pipeline. Not appropriate if you need NYHA functional class, a diagnosis, or if you lack pre-assessed clinical flags — this endpoint does not examine patients or interpret echocardiograms.

## Known failure modes

- Missing required boolean flags returns a validation error
- All flags false returns not_staged rather than an error
- Caller-supplied flags that are clinically incorrect will produce a logically consistent but medically wrong stage — the API does not validate clinical accuracy
- Non-boolean values for flag fields will fail schema validation

## How this service works

2013 ACCF/AHA heart-failure stages (Yancy) from four caller flags: high risk for HF, structural heart disease, prior or current HF symptoms, and refractory specialized care. Returns hf_stage A, B, C, D, or not_staged. Progressive and inviolate: D first, then C, B, A, else not_staged. Not NYHA class and not a diagnosis. magent does not examine the patient or read an echocardiogram.

## Output

Returns a single hf_stage field with one of five values: A (high risk, no structural disease or symptoms), B (structural disease, no symptoms), C (structural disease with prior or current symptoms), D (refractory HF requiring specialized care), or not_staged if none of the flags qualify under the algorithm. Staging is applied in strict D→C→B→A priority order.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "headers": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    },
    "queryParams": {
     "type": "object",
     "required": [
      "high_risk_for_hf",
      "structural_heart_disease",
      "hf_symptoms_prior_or_current",
      "refractory_hf_specialized"
     ],
     "properties": {
      "high_risk_for_hf": {
       "type": "boolean",
       "description": "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": {
       "type": "boolean",
       "description": "Structural heart disease as assigned by the caller (Yancy 2013 stage B or C). true or false. magent does not read an echocardiogram."
      },
      "refractory_hf_specialized": {
       "type": "boolean",
       "description": "Refractory HF requiring specialized interventions as assigned by the caller (Yancy 2013 stage D). true or false. magent does not examine the patient."
      },
      "hf_symptoms_prior_or_current": {
       "type": "boolean",
       "description": "Prior or current symptoms of HF as assigned by the caller (Yancy 2013 stage C). true or false. magent does not examine the patient."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/acc-aha-heart-failure-stage-calculator-yancy-2013-536665ae/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.magentlab.com](https://www.zero.xyz/host/api.magentlab.com/llms.txt)