A 54-year-old man comes to the emergency department after 2 weeks of shortness of breath. The patient gets out of breath easily when walking short distances and has felt more fatigued recently. He has a dry nighttime cough, which he attributes to a respiratory infection. He has not had any chest pain or pressure, palpitations, lightheadedness, or syncope. The patient was diagnosed with hypertension 3 years ago but does not take any medications. He has never smoked and drinks alcohol only socially. He has no family history of heart disease. Blood pressure is 162/90 mm Hg, and pulse is 98/min and regular. Which of the following would have the greatest sensitivity for diagnosing heart failure in this patient?

Question

A 54-year-old man comes to the emergency department after 2 weeks of shortness of breath.  The patient gets out of breath easily when walking short distances and has felt more fatigued recently.  He has a dry nighttime cough, which he attributes to a respiratory infection.  He has not had any chest pain or pressure, palpitations, lightheadedness, or syncope.  The patient was diagnosed with hypertension 3 years ago but does not take any medications.  He has never smoked and drinks alcohol only socially.  He has no family history of heart disease.  Blood pressure is 162/90 mm Hg, and pulse is 98/min and regular.  Which of the following would have the greatest sensitivity for diagnosing heart failure in this patient?

Quizplus · Accepted Answer

This patient with untreated hypertension now has progressive dyspnea on exertion with a nighttime cough, concerning for (but not diagnostic of) congestive heart failure (CHF). Brain natriuretic peptide (BNP) is a natriuretic hormone released from ventricular myocytes in patients with CHF in response to high ventricular filling pressures. An elevated plasma BNP level has high sensitivity (>90%) for the diagnosis of CHF. Elevated levels of circulating BNP correlate with the severity of left ventricular dysfunction and are useful in differentiating CHF from other causes of dyspnea. In studies of patients presenting with acute dyspnea, most patients with dyspnea due to CHF had plasma BNP levels >400 pg/mL whereas levels <100 pg/mL had a high negative predictive value for CHF as a cause of dyspnea. Such low values should prompt the search for noncardiac causes of dyspnea. (Choices A, B, D, F, and G) Clinical signs of CHF (eg, bilateral lung crackles, elevated jugular venous pressure, lower extremity edema, third heart sound) have high specificity for the diagnosis. However, their sensitivity is quite low; therefore, their absence should not be used to exclude CHF. Cardiomegaly on chest x-ray also has low sensitivity (~60%) for the diagnosis. (Choice E) Elevated plasma renin activity is a marker for activation of the renin-angiotensin system. However, it has no role in the diagnosis of CHF. Educational objective: Elevated plasma brain natriuretic peptide levels have high sensitivity for the diagnosis of congestive heart failure. In contrast, clinical signs of congestive heart failure (eg, bilateral lung crackles, elevated jugular venous pressure, lower extremity edema, third heart sound) have high specificity but low sensitivity for the diagnosis. References: Natriuretic peptides (BNP and NT-proBNP): measurement and relevance in heart failure. (http://www.ncbi.nlm.nih.gov/pubmed/20539843) Systematic review and individual patient data meta-analysis of diagnosis of heart failure, with modelling of implications of different diagnostic strategies in primary care. (http://www.ncbi.nlm.nih.gov/pubmed/19586584) Use of chest radiography in the emergency diagnosis of acute congestive heart failure. (http://www.ncbi.nlm.nih.gov/pubmed/16159971)

A 54-Year-Old Man Comes to the Emergency Department After 2