Is the bendopnea test a reliable indicator for detecting heart failure (HF) in patients with suspected heart failure?

Bendopnea Test for Heart Failure Detection

No, the bendopnea test cannot reliably determine whether a person with suspected heart failure has the condition—it is a symptom of advanced heart failure, not a diagnostic test, and should never replace established diagnostic methods like BNP testing, echocardiography, or clinical evaluation. 1

What Bendopnea Actually Is

Bendopnea is defined as shortness of breath that occurs within 30 seconds of bending forward (such as when tying shoes), with a median onset time of approximately 8 seconds. 2 This is a symptom that some heart failure patients experience, not a diagnostic test that can confirm or rule out heart failure. 3, 2

• Prevalence: Bendopnea occurs in only 28-49% of patients with confirmed heart failure, meaning more than half of heart failure patients do not have this symptom. 3, 2
• Mechanism: When present, bendopnea reflects already-elevated filling pressures (pulmonary capillary wedge pressure and right atrial pressure) that increase further during bending, particularly when cardiac index is reduced. 2

Why Bendopnea Cannot Diagnose Heart Failure

Poor Sensitivity and Specificity

• Bendopnea is present in only 28-49% of confirmed heart failure patients, making it an unreliable screening tool with poor sensitivity. 3, 2
• Bendopnea also occurs in 34.7% of patients with severe obstructive sleep apnea who do not have heart failure, demonstrating poor specificity. 4
• The symptom is associated with obesity, respiratory diseases, and other comorbidities unrelated to heart failure. 4

Not a Substitute for Established Diagnostics

The established diagnostic approach for suspected heart failure requires BNP or NT-proBNP testing in the acute setting to rule out or confirm heart failure, with Class I recommendation. 1

• BNP testing has 90% sensitivity and 76% specificity for diagnosing heart failure in patients with acute dyspnea, far superior to any physical examination finding. 1, 5
• A BNP cut-off of 100 pg/mL provides 81% diagnostic accuracy for determining heart failure as the cause of acute dyspnea. 1, 5
• For NT-proBNP, cut-points of 450 pg/mL (age <50 years) and 900 pg/mL (age ≥50 years) are highly sensitive and specific, with a negative predictive value of 99% for ruling out acute heart failure. 1, 5

Actual Role of Bendopnea in Clinical Practice

Prognostic Indicator, Not Diagnostic Tool

When bendopnea is present in patients with already-confirmed heart failure, it serves as a marker of disease severity and prognosis:

• Patients with bendopnea have higher mortality rates and more advanced NYHA functional class. 3
• Bendopnea is associated with worse functional capacity, higher NT-proBNP levels, lower 6-minute walking distance, and worse hemodynamic parameters. 6, 3
• However, bendopnea itself was not independently associated with risk of worsening heart failure events in one study, whereas the bending oxygen saturation index (BOSI) was predictive. 7

Limitations as a Clinical Sign

• Bendopnea produces moderate to severe quality of life limitation in 80.3% of those who experience it, but this does not make it a diagnostic tool. 3
• The symptom is more related to elevated filling pressures combined with reduced cardiac index (a "wet and cold" hemodynamic profile), but this profile can only be confirmed through invasive hemodynamic assessment or echocardiography. 2

Correct Diagnostic Approach for Suspected Heart Failure

For patients with suspected heart failure presenting acutely, measure BNP or NT-proBNP immediately, followed by echocardiography and ECG. 1

Step-by-Step Algorithm

1. Initial Assessment: Obtain BNP or NT-proBNP in the acute setting (Class I recommendation). 1

   • BNP <100 pg/mL or NT-proBNP <300 pg/mL makes heart failure unlikely (negative predictive value 99%). 5, 8
   • BNP >500 pg/mL or NT-proBNP >1,000 pg/mL makes heart failure likely. 9

2. Echocardiography: Perform 2D echocardiography with Doppler to assess left ventricular ejection fraction, chamber volumes, wall thickness, valve function, and diastolic function (Class I recommendation). 1

3. ECG: Obtain 12-lead ECG to assess rhythm, conduction abnormalities, and evidence of prior myocardial infarction. 1

   • A completely normal ECG makes heart failure very unlikely (<2% likelihood in acute presentations). 1

4. Laboratory Tests: Check complete blood count, renal function, electrolytes, liver function, and thyroid function to identify alternative causes and assess treatment safety. 1

Common Pitfalls to Avoid

• Do not rely on physical examination findings alone to diagnose or rule out heart failure—symptoms and signs are non-specific. 1
• Do not use bendopnea as a diagnostic criterion for heart failure, as it lacks sensitivity and specificity. 3, 4, 2
• Do not skip BNP/NT-proBNP testing in favor of clinical assessment alone, as biomarker testing improves diagnostic accuracy and reduces time to appropriate treatment. 1, 5
• Do not assume a normal echocardiogram rules out heart failure—consider heart failure with preserved ejection fraction (HFpEF) if BNP is elevated despite normal systolic function. 8, 9