Unexplained Dyspnea, Bendopnea, and Heart Failure With Preserved Ejection Fraction

Aaron B. Holley, MD


April 19, 2023

If you practice inpatient medicine, you've managed patients with heart failure with preserved ejection fraction (HFpEF). Formerly known as diastolic dysfunction, HFpEF is borderline ubiquitous on the medicine units. In the emergency department, if you see a dyspneic patient above the age of 40, HFpEF is at the top of your differential. Volume overload on chest x-ray, abnormal labs, and edema on exam with normal ejection fraction on your bedside echocardiogram — and just like that you're treating HFpEF, praying that the diuretic payload provides relief before the creatinine bumps.

That is familiar. But what about your outpatients with unexplained dyspnea without volume overload on exam? Let's say they have a normal brain natriuretic peptide (BNP) too and they've never been admitted for heart failure. Is HFpEF on your differential? My guess is that it's not (it wouldn't be on mine); but it should be because it presents that way a third of the time.

The Journal of the American Medical Association just published an excellent HFpEF review. If you haven't read it yet, you need to. If you're going to read this column instead, let me highlight some data that flew under my radar — and possibly yours. First, HFpEF diagnoses are increasing; by 2030, 3% of the US population above the age of 18 will receive the diagnosis. That's high. The most common symptom is dyspnea, but only 65% of patients with HFpEF are volume overloaded on presentation. As many as 30% can have normal BNP and proBNP levels, which will be more likely in the presence of obesity, normal kidney function, and younger age. Last, 50%-60% of patients with unexplained dyspnea without a defined etiology will have evidence of HFpEF on invasive testing.

So, consider this: Unexplained dyspnea is one of the more common complaints among outpatients. If the overall adult prevalence of HFpEF is approaching 3%, 35% of patients with HFpEF are euvolemic on exam, and 30% have normal BNP testing, I have a problem. I see a lot of adults with unexplained dyspnea, and if they're euvolemic with a normal BNP, I'm looking elsewhere for an etiology. This could be a mistake.

It gets muddier. Beyond it having a surprisingly subtle presentation in a surprisingly large proportion of outpatients with unexplained dyspnea, HFpEF mixes regularly with obesity, hypertension, and coronary artery disease and causes abnormalities on spirometry and diffusion capacity for carbon monoxide. They are probably on nodal blockade for atrial fibrillation, too. Patients with unexplained dyspnea and HFpEF will usually have multiple conditions driving their dyspnea. Plausible alternative diagnoses give smug cardiologists ammunition for their favorite phrase: "It's not the heart; it's the lungs." It is difficult to extract an HFpEF diagnosis from the comorbidity mess you're confronted with. Unfortunately, neither cardiologists nor pulmonologists are good at accepting the hard dyspnea truth: It's usually the heart and the lungs.

There is good news, though. Beyond increasing your level of suspicion, there are tools to help identify the HFpEF needle in the unexplained dyspnea haystack. Both the JAMA review and the recently published American College of Cardiology/American Heart Association/Heart Failure Society of America heart failure guidelines endorse a simple model in lieu of invasive testing. It's called the H2FPEF score and includes two echocardiography measures (RVSP > 35 mm Hg and E/e' > 9), age, body mass index, and comorbidities (hypertension and atrial fibrillation) to predict the presence of HFpEF on invasive exercise testing. This score performed well on external validation. It's not perfect but it's better than catheterizing everyone.

On a final note, that's not a typo in the title. The JAMA review uses the word bendopnea, a term coined a decade ago that refers to shortness of breath when bending over. It took me 15-20 minutes to stop laughing and regain my composure after I read it, at which point it resonated. I've actually heard this complaint repeatedly. I'd attributed it to some form of altered cortical processing in patients hyperattuned to their own breathing. I'll have to give my pet theory a second look. Perhaps these patients are telling me that they have HFpEF. Meanwhile, I can't wait to say "bendopnea" in a professional setting. A regional or national conference would be ideal, but I'm not confident that I can be that patient. I'm sure I can work it into a conversation while staffing fellows' clinic this Friday.

Aaron B. Holley, MD, is a professor of medicine at Uniformed Services University in Bethesda, Maryland, and a pulmonary/sleep and critical care medicine physician at MedStar Washington Hospital Center in Washington, DC. He covers a wide range of topics in pulmonary, critical care, and sleep medicine.

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