Episode 211: Understanding HFpEF.  

Hyo Mun and Jordan Redden (medical students) explain the pathophysiology of heart failure with preserved ejection fraction (HFpEF) and how it differentiates from HFrEF. Dr. Arreaza asks insightful questions and summarizes some key elements of HFpEF. 

Written by Hyo Mun, MS4, American University of the Caribbean; and Jordan Redden, MS4, Ross University School of Medicine. Comments and edits by Hector Arreaza, MD.

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What is EF? Just imagine, the heart is a pump, blood gets into the heart through the veins, the ventricles fill up and then squeeze the blood out. So, the percent of blood that is pumped out is the EF. Let’s start at the beginning. 

What is HFpEF?

Mike: HFpEF stands for heart failure with preserved ejection fraction. Basically, these patients squeeze normally—their ejection fraction is 50% or higher—but here's the thing: the heart can't relax and fill the way it should. The muscle gets stiff, almost like a thick leather boot that just won't stretch. And because the ventricle can't fill properly, pressure starts backing up into the lungs and the rest of the body. That's when patients start experiencing shortness of breath, leg swelling, fatigue—all those classic symptoms.

Dr. Arreaza: And this is where people get fooled by the ejection fraction.

Mike: Exactly. The ejectionfraction tells you total left ventricular emptying, not just forward flow.

Jordan: The classic example is severe mitral regurgitation. You can eject 60% of your blood volume and still be in cardiogenic shock because most of that blood is leaking backward into the left atrium instead of going into the aorta. So, you get pulmonary edema, hypotension, fatigue, all with a “normal” EF. Which is honestly terrifying if you’re over-relying on echo reports without thinking clinically.

Dr. Arreaza: And in HFpEF, functional mitral regurgitation often shows up later in the disease. It’s not usually the primary cause; it’s more of a marker of advanced disease. Moderate to severe MR in HFpEF independently predicts worse outcomes, including a higher risk of mortality or heart failure hospitalization. So, let’s contrast this with HFrEF. How are these two different?

Mike: HFrEF—heart failure with reduced ejection fraction—is a pumping problem. The heart muscle is weak and can't contracteffectively. Ejection fraction drops below 40%, and this is your classic systolic dysfunction.

Jordan: HFpEF, on the other hand, is diastolic dysfunction. The heart muscle is thick, fibrotic, and noncompliant. It squeezes fine, but it just doesn’t relax, even though the EF looks reassuring on paper.

Mike: I like to explain it this way: HFrEF is a weak heart that can't squeeze. HFpEF is a stiff heart that can't relax. Totally different problems.

Dr. Arreaza: And then there’s the gray zone: heart failure with mildly reduced EF, or HFmrEF. That’s an EF between 41 and 49% with evidence of elevated filling pressures. It really shares the features of both worlds. So, what actually causes HFpEF versus HFrEF?

Jordan: HFpEF is basically what happens when all the problems of modern living catch up with you. You've got chronic hypertension, obesity, diabetes, metabolic syndrome, aging, systemic inflammation—all of these things slowly remodel the heart over years. The muscle gets