{"uid":"cap_O7194l3wB0LAZ5_qE_F2w","slug":"steinhart-2009-acute-heart-failure-probability-calculator-4cf7989e","name":"Steinhart 2009 Acute Heart Failure Probability Calculator","description":"Steinhart 2009 Equation 1 probability of acute heart failure from caller-assigned age, clinician pretest probability (fraction 0-1 or 0-100 percent), and NT-proBNP in pg/mL. Returns estimated_probability_percent from the unrounded probability plus published ≤0.20 rule-out and ≥0.80 rule-in flags. Not a diagnosis, diuretic, or admission order. magent does not assay NT-proBNP.","url":"https://api.magentlab.com/api/calc/steinhart","method":"GET","headers":{},"bodySchema":{"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":["age","pretest_probability","nt_probnp_pg_ml"],"properties":{"age":{"type":"integer","description":"Age in years, integer 18-100. Steinhart 2009 Equation 1 coefficient -0.011 per year. magent does not read an identity document."},"nt_probnp_pg_ml":{"type":"number","description":"NT-proBNP in pg/mL (5-35000). Enters as log10. Not pmol/L; magent does not convert units or assay NT-proBNP."},"pretest_probability":{"type":"number","description":"Caller-assigned clinician pretest probability of acute heart failure before NT-proBNP. Fraction 0-1, or 0-100 percent (values above 1 are divided by 100). 1 means certainty, not 1 percent. Steinhart 2009 coefficient -5.914 on the fraction. magent does not assign pretest probability or examine the patient."}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.005","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.005/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_I6q7L7UH0WJ-_lKtWTEAW","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.005","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Calculates the probability of acute heart failure using the Steinhart 2009 Equation 1 logistic model from age, clinician pretest probability, and NT-proBNP level, with rule-out and rule-in flags.","exampleAgentPrompt":"Using the Steinhart 2009 model, what's the probability this 72-year-old patient has acute heart failure? The clinician's pretest probability is 0.45 and the NT-proBNP came back at 3200 pg/mL.","exampleUseCases":[{"title":"Emergency ED triage for dyspnea","prompt":"I have a 68-year-old presenting with shortness of breath in the ED — pretest probability of heart failure is about 0.6 and the NT-proBNP is 5800 pg/mL. Can you run the Steinhart 2009 equation to estimate the acute heart failure probability and tell me if it hits the rule-in threshold?"},{"title":"Low-risk rule-out in urgent care","prompt":"A 55-year-old came in with mild dyspnea, my pretest probability for heart failure is 0.15, and their NT-proBNP is 180 pg/mL. Run the Steinhart 2009 model and let me know if we can rule out acute heart failure."},{"title":"Borderline NT-proBNP clinical decision support","prompt":"Patient is 80 years old, NT-proBNP is 1100 pg/mL, and my pretest probability is 0.50. What does the Steinhart 2009 equation give for acute heart failure probability, and does it trigger any rule-in or rule-out flag?"}],"resultDescription":"Returns an estimated_probability_percent representing the unrounded Steinhart 2009 Equation 1 logistic model output, plus boolean flags indicating whether the probability meets the published ≤0.20 rule-out or ≥0.80 rule-in thresholds for acute heart failure. Does not provide a diagnosis or clinical order.","failureModes":["Missing required parameters (age, pretest_probability, or nt_probnp_pg_ml) returns a validation error","Age outside 18-100 range may be rejected or produce out-of-validation-range results","NT-proBNP outside 5-35000 pg/mL range may produce unreliable results","Pretest probability provided in percent (e.g. 45) is auto-divided by 100; misuse of scale can yield unexpected results","NT-proBNP provided in pmol/L instead of pg/mL will silently produce incorrect probabilities since no unit conversion is performed","Payment failure via x402 protocol returns 402 status with no computation"],"whenToPreferThis":"Use this endpoint when you need a validated, published logistic model (Steinhart 2009 Equation 1) specifically for acute heart failure probability combining NT-proBNP, clinician pretest probability, and age. Prefer this over generic biomarker lookup tools when you need an interpreted probability with rule-in/rule-out decision thresholds. Not appropriate for chronic heart failure risk scoring (see MAGGIC) or ACS probability (see T-MACS).","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T07:01:59.219Z","isFirstParty":false}