From the Guidelines
The NT-proBNP level of 94 pg/mL, which is below the threshold of 300 pg/mL, suggests that acute heart failure syndrome is unlikely to be the cause of the shortness of breath on exertion, as indicated by the guidelines that a NT-proBNP < 300 pg/dL makes acute heart failure syndrome unlikely 1. Given this result, it is reasonable to focus on alternative causes for the shortness of breath, such as:
- Pulmonary conditions like asthma or COPD
- Deconditioning
- Anemia
- Other non-cardiac etiologies Further evaluation should include:
- Pulmonary function testing
- Complete blood count to check for anemia
- Chest imaging
- Possibly an exercise stress test to evaluate exercise capacity and response While the normal NT-proBNP effectively rules out heart failure with good sensitivity, it's crucial to correlate this finding with the clinical presentation and other diagnostic tests 1. If symptoms persist or worsen despite the normal NT-proBNP, additional cardiac evaluation might still be warranted, as some early cardiac conditions may not yet cause significant elevation in natriuretic peptides.
From the Research
NT-proBNP Levels and Shortness of Breath
- The patient's NT-proBNP level is 94, which is less than 450, and was ordered for shortness of breath (SOB) on exertion 2, 3.
- Studies have shown that NT-proBNP levels can be used to diagnose heart failure and heart stress, and that elevated levels can indicate cardiac dysfunction 2, 3, 4.
- A study published in the European journal of heart failure found that NT-proBNP levels can be used to rule in or rule out acute heart failure in the emergency department and to diagnose de novo heart failure in the outpatient setting 2.
- Another study published in Respiration found that NT-proBNP levels can be used to identify heart disease and cardiac causes of dyspnea among patients referred for evaluation by a pulmonologist, with a sensitivity of 0.75 and specificity of 0.79 for identifying heart disease 3.
Diagnostic Criteria
- The study published in the European journal of heart failure proposed a simple acronym, FIND-HF, to consider heart failure: Fatigue, Increased water accumulation, Natriuretic peptide testing, and Dyspnoea 2.
- The study published in Respiration found that NT-proBNP levels can be used as a rule-out test for cardiac dyspnea, with a negative predictive value of 0.90 3.
- The study published in the European heart journal found that an NT-proBNP level <300 pg/mL had a negative predictive value of 91% for significant left ventricular systolic and diastolic dysfunction 4.
Clinical Implications
- The patient's NT-proBNP level of 94 is below the cut-off value of 300 pg/mL, which suggests a low likelihood of significant left ventricular systolic and diastolic dysfunction 4.
- However, the patient's symptoms of shortness of breath on exertion should still be evaluated further to determine the underlying cause 5, 3, 4.
- The patient's NT-proBNP level and symptoms should be considered in the context of their overall clinical presentation and medical history 2, 3, 4.