Diastolic heart failure is a type of heart failure where your heart pumps normally but is too stiff to fill with enough blood between beats. The heart’s squeezing power, measured as ejection fraction, stays at 50% or above, which is why doctors now call this condition heart failure with preserved ejection fraction (HFpEF). It accounts for roughly half of all heart failure cases, and it’s becoming more common as the population ages.
How a Stiff Heart Causes Problems
In a healthy heart, the left ventricle relaxes completely after each beat, creating a low-pressure space that draws blood in from the lungs. In diastolic heart failure, two things go wrong with that process. First, the heart muscle relaxes too slowly. Research published in the New England Journal of Medicine found that the relaxation phase in diastolic heart failure patients took nearly twice as long as in healthy controls (59 milliseconds versus 35). Second, the muscle wall itself becomes physically stiffer, roughly three times stiffer than normal in the same study.
Because the ventricle can’t relax and stretch the way it should, pressure builds up inside the heart chamber. That elevated pressure pushes backward through the pulmonary veins into the lungs, which is why shortness of breath is the hallmark symptom. The heart is still contracting with normal force, so standard tests of pumping strength look fine. The problem is entirely on the filling side.
How It Differs From Systolic Heart Failure
Systolic heart failure, known as heart failure with reduced ejection fraction (HFrEF), is the other major type. In that condition, the heart muscle weakens and loses its ability to contract, dropping the ejection fraction below 40%. The ventricle often stretches outward (eccentric hypertrophy), and there’s significant loss of heart muscle cells.
Diastolic heart failure looks different at the cellular level. The heart wall thickens inward (concentric hypertrophy), but the muscle cells themselves don’t die off the way they do in systolic failure. Instead, fibrosis, inflammation, and changes to the internal proteins that give heart muscle its elasticity make the wall rigid. Both types produce the same symptoms, including fluid buildup, fatigue, and breathlessness, but they arise from opposite mechanical problems: one is a squeezing failure, the other is a filling failure.
Who Gets Diastolic Heart Failure
High blood pressure is the single most important driver. When the heart pumps against chronically elevated pressure, the muscle wall thickens to compensate. Over years, that thickening makes the wall stiffer. Obesity and diabetes independently contribute by promoting inflammation and fibrosis in the heart muscle. Sleep apnea, chronic kidney disease, thyroid disorders, and anemia also raise risk.
Age is a major factor on its own. People 65 and older have a significantly higher risk because aging naturally stiffens and weakens heart tissue. Diastolic heart failure is more common in older women than in men, partly because women are more likely to develop the concentric thickening pattern in response to high blood pressure.
Symptoms to Recognize
The symptoms of diastolic heart failure are identical to those of systolic heart failure, and they show up with equal frequency. The most common is shortness of breath during physical activity. Because the stiff ventricle can’t increase its filling volume during exercise the way a healthy heart does, even moderate exertion can leave you winded. At rest, the heart may manage well enough that you feel fine, which is why early cases often go unnoticed.
As the condition progresses, you may notice:
- Fatigue and low energy, caused by reduced blood flow to muscles and organs
- Swelling in the ankles, legs, or abdomen, from fluid backing up in the veins
- Shortness of breath when lying flat, because fluid shifts toward the lungs in that position
- Waking up at night gasping for air
- Rapid or unexplained weight gain from fluid retention
On examination, a doctor might hear crackling sounds in the lungs, see distended neck veins, or detect an extra heart sound called a gallop. Chest X-rays often show fluid redistribution in the lungs or fluid around the lung lining, even when pumping function appears normal.
How It’s Diagnosed
Diagnosis starts with an echocardiogram, an ultrasound of the heart. If the ejection fraction is 50% or higher but symptoms of heart failure are present, diastolic heart failure becomes the leading possibility. The echocardiogram can also measure how blood flows through the heart’s valves and how quickly the heart muscle relaxes, which helps grade the severity of the problem.
Diastolic dysfunction is classified into grades based on several ultrasound measurements. Grade I (impaired relaxation) is the mildest form and may not cause symptoms at rest. Grade II (pseudonormal filling) means filling pressures have risen enough to mask the relaxation problem on basic measurements, requiring additional parameters to detect. Grade III (restrictive filling) reflects severely elevated pressures. Key indicators that suggest elevated filling pressures include a left atrial volume index above 34 ml/m², and specific ratios of blood flow velocity across the heart valve compared to the speed of heart wall movement (an average E/e’ ratio above 14).
Blood tests for natriuretic peptides (BNP or NT-proBNP) help confirm or rule out heart failure. These hormones are released when the heart is under strain, and elevated levels support the diagnosis.
Prognosis and Hospitalization Risk
Diastolic heart failure is a serious condition. One-year mortality ranges from 20 to 29%, according to data compiled by the American College of Cardiology. Hospital readmissions are frequent, with a 30-day all-cause readmission rate of about 21%. These numbers are comparable to systolic heart failure, which is important because diastolic failure was historically considered the “milder” form. It isn’t.
Treatment Options
For decades, diastolic heart failure had no treatments proven to reduce death or hospitalization, a frustrating contrast with systolic heart failure, which has several effective drug classes. That changed with a newer class of medications originally developed for diabetes, called SGLT2 inhibitors. Clinical trials (EMPEROR-Preserved and DELIVER) showed these drugs reduce heart failure hospitalizations in HFpEF patients. The 2022 American Heart Association guidelines give them a strong recommendation. They’re taken as a single daily pill with no need for dose adjustments or routine blood work monitoring.
Beyond that, treatment focuses on controlling the conditions that caused the stiffness in the first place. Bringing blood pressure to target is critical. Managing blood sugar in diabetes, treating sleep apnea, and losing weight if you’re obese all reduce the strain on the heart and can improve how well it fills. Diuretics (water pills) are commonly prescribed to relieve fluid buildup and ease breathing, though they treat symptoms rather than the underlying stiffness.
Sodium and Fluid Management
Limiting salt intake is a standard recommendation for managing fluid retention, though the exact target is debated. The American Heart Association advises keeping sodium below 2,300 mg per day for general cardiovascular health. The European Society of Cardiology recommends staying under 5 grams of salt per day (salt is about 40% sodium, so this works out to roughly 2,000 mg of sodium) and emphasizes individualized counseling rather than strict universal limits. The Canadian Cardiovascular Society suggests 2,000 to 3,000 mg of sodium daily.
Some clinical protocols also restrict fluid intake to less than 1,500 mL per day (about 50 ounces) during periods of significant fluid overload. In practice, most people with stable diastolic heart failure benefit from paying consistent attention to sodium without needing to measure every milligram. Reading nutrition labels, cooking at home more often, and reducing processed food intake make the biggest difference for most patients.
Exercise and Physical Activity
Exercise intolerance is one of the defining features of diastolic heart failure, but regular physical activity is also one of the most effective ways to improve it. Structured aerobic exercise, even at moderate intensity, has been shown to improve how well the heart fills, reduce stiffness, and meaningfully increase exercise capacity. Walking, cycling, and supervised cardiac rehabilitation programs are common starting points. The key is consistent, gradual activity rather than occasional intense effort.