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Update your Knowledge with MKSAP 19 Q&A: Answer and Critique

Answer

A: Heart failure with preserved ejection fraction

Educational Objective

Diagnose heart failure with preserved ejection fraction.

Critique

The most likely diagnosis is heart failure with preserved ejection fraction (HFpEF) (Option A). The diagnosis of HFpEF should be suspected in patients who meet the following three criteria: symptoms of heart failure, left ventricular (LV) ejection fraction of 50% or greater, and no other apparent cause of heart failure symptoms. HFpEF accounts for approximately half of heart failure cases. Classic symptoms include exertional dyspnea, paroxysmal nocturnal dyspnea, and orthopnea. Physical findings in heart failure, such as an S3, elevated central venous pressure, crackles, and peripheral edema, are highly specific but insensitive, and their absence does not exclude heart failure. Natriuretic peptide levels may be normal in patients with heart failure, particularly in those with obesity or only exertional symptoms. Echocardiographic features of HFpEF include normal LV cavity size, increased LV wall thickness, left atrial enlargement, abnormal diastolic function, and elevated pulmonary artery systolic pressure (>35 mm Hg).

High-output heart failure (Option B) is characterized by symptoms of heart failure in the setting of a cardiac index greater than 4 L/min/m2. Causes include obesity, anemia, hyperthyroidism, Paget disease of bone, thiamine deficiency, and arteriovenous fistula. The patient's normal cardiac index rules out this diagnosis.

Hypertrophic obstructive cardiomyopathy (Option C) may cause dyspnea; however, a systolic murmur would be present on examination, and the echocardiogram would demonstrate resting or provoked outflow tract obstruction.

The patient's LV hypertrophy and elevated right ventricular systolic pressure make noncardiac dyspnea (Option D) less likely. Predictive scores can exclude noncardiac causes of dyspnea with a high degree of reliability. The Heart Failure Preserved Ejection Fraction (H2FpEF) risk score, which relies on simple clinical and echocardiographic characteristics, is a means to assess the likelihood of HFpEF and is used to discriminate cardiac versus noncardiac causes of dyspnea. Predictive variables include obesity (2 points), atrial fibrillation (3 points), age older than 60 years (1 point), treatment with at least two antihypertensive drugs (1 point), echocardiographic E/e′ ratio greater than 9 (1 point), and echocardiographic pulmonary artery systolic pressure greater than 35 mm Hg (1 point). This patient's H2FpEF risk score is 8, suggesting that her dyspnea has a cardiac cause and that further diagnostic evaluation of dyspnea is unnecessary.

Key Point

Heart failure with preserved ejection fraction should be suspected in patients who meet the following three criteria: symptoms of heart failure, left ventricular ejection fraction of 50% or greater, and no other apparent cause of heart failure symptoms.

Bibliogrpahy

Reddy YNV, Carter RE, Obokata M, et al. A simple, evidence-based approach to help guide diagnosis of heart failure with preserved ejection fraction. Circulation. 2018;138:861-70. [PMID: 29792299] doi:10.1161/CIRCULATIONAHA.118.034646

Back to the May 2022 issue of ACP Global