Walking but Elevated BNP: When Functional Capacity and Biomarkers Disagree
Daily walking does not confirm functional capacity. When FC and BNP conflict, the discordance itself becomes the starting point for evaluation.
Clinical scenario
A 68-year-old man is referred for preoperative assessment before elective colorectal resection for colon cancer. The surgical team notes 'patient appears active and functional.' Preoperative BNP is 180 pg/mL (institutional threshold: 92 pg/mL). Can you proceed?
He reports walking 20 minutes daily. On closer questioning, he avoids hills and pauses on a single flight of stairs. History: type 2 diabetes (oral medication), hypertension (ARB). No prior cardiac diagnosis. HR 78, BP 140/82, SpO₂ 97%. ECG: sinus rhythm, no significant abnormalities.
When to use this page
When self-reported walking ability and preoperative BNP are pointing in opposite directions. When something doesn't add up.
Walking is not the same as adequate functional capacity
Key point
Reporting daily walks does not confirm functional capacity ≥ 4 METs. Avoiding hills and pausing on a single flight of stairs may indicate that functional capacity is actually impaired.
The ability to walk is evidence of mobility — not cardiac reserve. The relevant question is whether the patient can sustain activities at or above 4 METs without symptoms. Avoiding hills and pausing on stairs are behavioral signals of exertional limitation. When activities equivalent to 4 METs cannot be confirmed (e.g., climbing two flights without stopping, brisk walking on flat ground), functional capacity should be treated as unknown. Structured tools such as the DASI (Duke Activity Status Index) provide a more objective estimate than open-ended self-report.
What BNP 180 pg/mL means here
BNP elevation is a signal for further evaluation
BNP 180 pg/mL substantially exceeds the institutional threshold (92 pg/mL) and represents an objective signal of increased cardiac wall stress. It is not a reason to postpone surgery — it is a reason to understand why it is elevated.
BNP is not a diagnostic test; it is a risk signal. Elevation can result from multiple causes, and the appropriate clinical action depends on identifying which cause is present.
- Subclinical left ventricular dysfunction (heart failure without recognized symptoms)
- Diastolic dysfunction
- Valvular heart disease (including asymptomatic severe valvulopathy)
- Renal impairment (reduced clearance with declining eGFR)
- Atrial fibrillation
How to approach the discordance
- ① Reassess functional capacity: move beyond 'I walk daily' — ask specifically about hills, stairs, and DASI items
- ② Investigate the cause of BNP elevation: review prior echocardiography, renal function, valvular history, and rhythm
- ③ Confirm RCRI factors: diabetes, CKD, ischemic heart disease, heart failure, stroke history, high-risk surgery
- ④ Determine whether echocardiography is warranted: if the cause of BNP elevation is unclear, imaging may be needed
- ⑤ Decide whether cardiology evaluation is indicated: based on findings from steps ①–④, not from BNP elevation alone
Basis for this approach
ACC/AHA 2014 Guideline on Perioperative Cardiovascular Evaluation (biomarker section) / ESC 2022 Guidelines on Cardiovascular Assessment and Management of Patients Undergoing Non-cardiac Surgery (BNP/NT-proBNP: Class IIa) / JCS 2022 Guidelines on Perioperative Cardiovascular Evaluation for Non-cardiac Surgery
Walking but elevated BNP. How do you approach this discordance?
- 1.BNP is mildly elevated but patient walks daily — proceed as planned⚠ Not recommended
FC is self-reported. BNP is an objective signal of cardiac wall stress. Discordance between the two requires evaluation, not reassurance.
- 2.
When FC and BNP conflict, BNP becomes a signal for further evaluation. Identifying the cause determines what comes next.
- 3.
Serial measurement may have value in specific situations, but investigating the underlying cause should come before repetition.
Teaching points
- Walking every day does not confirm functional capacity ≥ 4 METs — ask specifically about hills and stairs, and consider the DASI.
- When FC and BNP conflict, neither value alone is sufficient for a decision. The discordance itself is clinically meaningful.
- BNP elevation is a signal to investigate the underlying cause of cardiac stress — not an automatic reason to postpone surgery.
- Biomarkers and functional history complement each other. Identifying the cause of BNP elevation determines whether to proceed, optimize, or refer.
Next clinical question
Further evaluation identifies previously unrecognized ischemic heart disease. What should be assessed next?
Case: Ischemic heart disease history →Continue learning
Dyspnea on Stairs: Is Functional Capacity Really Adequate?
Patients often report that they are 'active' or 'walking regularly.' That does not mean they have adequate functional capacity. This case teaches how to move from symptom to functional limitation to perioperative decision.
Elevated BNP Before Surgery: A Signal, Not a Diagnosis
BNP 250 pg/mL. An elevated BNP does not diagnose heart failure. It signals that cardiac stress may be present. The key question is why it is elevated.
A Prior PCI Is Not the Whole Story: Assessing Coronary Disease Before Surgery
When a patient has a history of PCI, the first question is not about antiplatelet therapy. The first question is whether coronary artery disease remains stable today.
Apply this in practice
FC and BNP in conflict → enter all three factors into the Navigator to see the integrated assessment
Verify this decision in the tool →