Heart Failure Diagnosis and Cardiac Function Assessment

Diagnostic Criteria and Exclusion Thresholds

BNP >100 pg/mL is required to suggest chronic heart failure is likely 1, 2
The European Society of Cardiology guidelines state that BNP <100 pg/mL makes chronic heart failure "unlikely" 1, 2
For acute presentations, the lower exclusion threshold is 100 pg/mL for BNP 3
A normal BNP level combined with a completely normal ECG makes heart failure, especially with systolic dysfunction, unlikely (<10% probability) 1, 2

If the ECG is completely normal, heart failure—particularly with systolic dysfunction—is unlikely (<10% probability) 1, 2
Normal ECG combined with preserved ejection fraction essentially excludes reduced ejection fraction heart failure 1, 2

Ejection fraction of 55-60% is normal and indicates preserved systolic function 4, 5
Heart failure with reduced ejection fraction (HFrEF) is defined as EF ≤40% 4, 6
EF ≥50% defines HF with preserved EF if HF were present 4, 5

New symptoms such as progressive shortness of breath, leg swelling, orthopnea (difficulty breathing when lying flat), or paroxysmal nocturnal dyspnea warrant reassessment 4, 5
In patients with unexplained exertional dyspnea despite normal resting tests, exercise testing or stress echocardiography might reveal elevated filling pressures with exertion that aren't apparent at rest 4, 5
The 2022 ACC/AHA guidelines note that HF with preserved EF can be challenging to diagnose and may require evidence of elevated filling pressures during provocation (exercise, fluid challenge) 4

Stage B heart failure (pre-heart failure) is defined as having structural changes but no symptoms or clinical HF 4
Stage B patients have risk factors and structural abnormalities but do not have active heart failure and do not require HF-specific medications 4
Focus should be on managing cardiovascular risk factors (hypertension, diabetes, cholesterol) to prevent progression in Stage B patients 4