Preserved ejection fraction means the heart still squeezes out a normal percentage of blood with each beat, typically 50% or more, yet the person still has heart failure. This sounds contradictory, but the problem isn’t with pumping. It’s with filling. The heart muscle has become too stiff or too slow to relax properly between beats, so it can’t take in enough blood, especially during physical activity. The medical shorthand for this condition is HFpEF (heart failure with preserved ejection fraction), and it accounts for roughly half of all heart failure cases.
How Ejection Fraction Works
Ejection fraction is the percentage of blood your left ventricle pushes out each time it contracts. A healthy heart ejects about 55% to 70% of the blood it holds. In the type of heart failure most people picture, that number drops well below 40%, meaning the heart is too weak to pump effectively. That’s called heart failure with reduced ejection fraction.
In preserved ejection fraction, the pumping number looks normal on an echocardiogram, at 50% or above. This is precisely why the condition was overlooked for decades. The heart appears to be working fine by the most common measure, yet the person is breathless, fatigued, and retaining fluid. The dysfunction is happening in a different phase of the heartbeat: the relaxation phase, when the chambers should be expanding and filling with blood.
Why the Heart Fails Despite Normal Pumping
Nearly all patients with HFpEF have some degree of diastolic dysfunction, meaning problems with how the heart relaxes and fills. Two overlapping mechanisms drive it. First, the heart muscle loses its passive flexibility. The walls become stiffer, often from thickening (hypertrophy) caused by years of high blood pressure or other stress. A stiffer ventricle resists filling, so pressure inside the chamber rises even though the volume of blood entering it is lower than it should be.
Second, the muscle actively relaxes more slowly between contractions. At the cellular level, the tiny molecular bridges that pull muscle fibers together during a heartbeat take longer to release. Calcium, which triggers each contraction, isn’t cleared from muscle cells fast enough. Research on heart tissue from patients with thickened ventricles has shown that incomplete relaxation can begin at heart rates as low as 100 to 110 beats per minute, a rate you’d reach just walking up a flight of stairs. This explains why people with HFpEF often feel fine at rest but become short of breath with even mild exertion.
During exercise, the stiff ventricle can’t increase its filling to match the body’s demand for more blood flow. Pressure backs up into the lungs, stroke volume fails to rise, and the result is breathlessness and fatigue. There’s also evidence that the body’s ability to extract oxygen from blood in the muscles is impaired in HFpEF, compounding the exercise limitation from a second direction.
Symptoms and How They Show Up
Exercise intolerance is the defining symptom. It shows up early, persists throughout the course of the disease, and is the biggest driver of reduced quality of life. In practical terms, it means activities that once felt easy, like carrying groceries, climbing stairs, or walking at a moderate pace, now leave you winded or exhausted. A useful self-test that clinicians sometimes reference: if you can’t hold a conversation while walking up a flight of stairs, that’s a signal worth investigating.
Beyond exercise intolerance, the symptoms overlap heavily with other forms of heart failure. Shortness of breath (especially when lying flat or during activity), swollen ankles and legs, fatigue that rest doesn’t fully relieve, and waking up at night gasping for air are all common. Because these symptoms develop gradually and often in older adults who may attribute them to aging, HFpEF frequently goes undiagnosed for months or years.
Who Gets HFpEF
HFpEF has a distinct risk profile compared to other forms of heart failure. It’s overwhelmingly a disease of older adults. Among people 65 and older, HFpEF makes up roughly 70% of heart failure cases. A large meta-analysis of cohort studies identified five conditions that most strongly predict developing HFpEF:
- Atrial fibrillation carries the highest risk, nearly tripling the likelihood.
- Hypertension more than doubles the risk and is the single most common underlying cause.
- Diabetes raises risk by about 88%.
- Obesity increases risk by 70%.
- Prior heart attack raises risk by roughly 62%.
Most patients don’t have just one of these conditions. They have several, and the interplay between them, chronic inflammation from excess weight, blood vessel stiffening from high blood pressure, metabolic stress from diabetes, drives the progressive stiffening of the heart muscle over time. This cluster of overlapping conditions is one reason HFpEF has been so difficult to treat with any single medication.
How HFpEF Is Diagnosed
Diagnosis is genuinely challenging because no single test confirms it. European guidelines define HFpEF as the combination of heart failure symptoms, an ejection fraction of 50% or above on echocardiogram, and objective evidence that the heart’s structure or filling function is abnormal. A blood test for a protein called NT-proBNP is typically the first step. This protein rises when the heart is under strain. Levels below about 125 ng/L make heart failure unlikely, while levels above 400 ng/L generally prompt an echocardiogram within six weeks. Very high levels, above 2,000 ng/L, warrant imaging within two weeks because they’re associated with worse outcomes.
The echocardiogram does most of the diagnostic heavy lifting. It measures ejection fraction, checks for wall thickening or enlargement of the heart’s upper chambers, and assesses how well the ventricle relaxes and fills. A structured scoring system called HFA-PEFF combines three categories of evidence: blood biomarker levels, structural measurements (like the size of the left atrium and the thickness of the heart wall), and functional markers that reflect stiffness and filling pressure. If results remain uncertain at rest, exercise stress testing can unmask filling problems that only appear when the heart rate increases.
One complication with NT-proBNP in HFpEF specifically is that levels tend to be lower than in reduced ejection fraction heart failure, sometimes falling in a gray zone that’s hard to interpret. For detecting diastolic dysfunction, lower thresholds (around 269 ng/L in one study) perform better than the standard cutoffs designed for heart failure broadly.
Treatment Options
For years, HFpEF had no proven drug therapy. Medications that dramatically improved survival in reduced ejection fraction heart failure repeatedly failed in HFpEF trials. That changed with a class of drugs originally developed for diabetes called SGLT2 inhibitors. Two large clinical trials, EMPEROR-Preserved and DELIVER, demonstrated that these medications reduce hospitalizations and improve outcomes in HFpEF regardless of whether the patient has diabetes.
Based on this evidence, the 2023 European Society of Cardiology guidelines now recommend SGLT2 inhibitors for heart failure across the entire ejection fraction spectrum. They are considered first-line therapy due to their safety profile, tolerability, and the simplicity of a once-daily pill. Beyond these medications, treatment focuses heavily on managing the conditions driving the disease: controlling blood pressure, managing blood sugar, losing weight, and treating atrial fibrillation. Diuretics help relieve fluid buildup and shortness of breath but don’t change the long-term course.
Supervised exercise training is one of the most effective non-drug interventions. While exercise intolerance is the hallmark symptom, structured physical activity has been shown to improve fitness, reduce symptoms, and partially reverse some of the heart’s structural and metabolic changes. Programs are typically tailored to start gently and build gradually.
Long-Term Outlook
HFpEF is a serious condition. In one long-term observational study following patients after acute episodes, roughly two-thirds had died within five years. About half of those deaths were from cardiovascular causes, and the other half from non-cardiovascular conditions like cancer, infection, and kidney disease. This split is distinctive. In reduced ejection fraction heart failure, the heart itself is responsible for a larger share of deaths. In HFpEF, the burden of multiple coexisting illnesses contributes heavily to overall mortality.
The proportion of heart failure cases classified as HFpEF has been rising steadily. Data from a large U.S. registry of over 110,000 hospitalizations showed HFpEF’s share climbing from 33% in 2005 to 39% in 2010, while reduced ejection fraction’s share declined. This trend reflects an aging population and increasing rates of obesity, diabetes, and hypertension. Understanding what preserved ejection fraction actually means, and recognizing that a “normal” pumping percentage doesn’t equal a normal heart, is increasingly important as this form of heart failure becomes more common.