Diastolic heart failure is a type of heart failure where your heart pumps normally but can’t relax and fill with blood properly between beats. The heart muscle becomes stiff, so less blood enters the chamber before each contraction. Despite squeezing with normal force, the heart delivers less blood to the body because it’s working with a smaller volume each time. This condition accounts for roughly one-third of all heart failure cases, though some estimates range higher.
How It Differs From Systolic Heart Failure
Heart failure comes in two main forms, and the distinction matters because the underlying problem is different. In systolic heart failure, the heart muscle is weak and can’t contract forcefully enough. It pushes out less than 40% of the blood in the chamber with each beat, a measurement called ejection fraction. In diastolic heart failure, the heart squeezes just fine, maintaining an ejection fraction of 50% or higher, but the chamber is too stiff to fill completely. You’ll sometimes see diastolic heart failure called “heart failure with preserved ejection fraction,” or HFpEF, because that pumping percentage looks normal on testing.
The tricky part: both types produce nearly identical symptoms. Shortness of breath, fatigue, swelling in the legs and ankles, and difficulty exercising show up in both. There’s no reliable way to tell them apart based on how you feel. The distinction requires imaging and lab tests, which is one reason diastolic heart failure often goes undiagnosed or gets diagnosed late.
What Makes the Heart Stiff
Inside the heart muscle, a giant protein called titin acts like a molecular spring, controlling how much the muscle stretches between beats. In diastolic heart failure, chemical changes to titin increase the resting tension of individual heart cells, making them resist stretching. Think of it like a rubber band that has lost its elasticity. The muscle can still squeeze, but it can’t relax and open up fully afterward.
A second problem compounds the first. After each contraction, heart muscle cells need to quickly clear out calcium (the signal that triggers contraction) so the muscle can relax. In diastolic heart failure, that calcium removal is impaired, so the muscle stays partially contracted longer than it should. The cells also take longer to physically detach the tiny molecular hooks that drive contraction. The result is a heart that relaxes slowly and incompletely, leaving less time and space for blood to flow in before the next beat.
Over time, the heart wall may thicken in response to high blood pressure or other stressors, further reducing the chamber’s ability to expand. This remodeling reinforces the stiffness at both the cellular and structural level.
Who Is Most at Risk
Diastolic heart failure clusters around a specific set of conditions. High blood pressure is the single biggest driver, because years of pumping against elevated pressure causes the heart wall to thicken and stiffen. Obesity plays a major role as well, both through increased demand on the heart and through inflammation that directly affects heart muscle cells. Diabetes, coronary artery disease, and chronic kidney disease each contribute independently.
Atrial fibrillation, an irregular heart rhythm, is both a risk factor and a consequence. It disrupts the timing of how blood flows into the lower chambers, worsening the filling problem. Obstructive sleep apnea, which causes repeated drops in oxygen overnight, also stresses the heart in ways that promote stiffening. Less commonly, infiltrative diseases like amyloidosis (where abnormal proteins deposit in the heart muscle) can cause severe diastolic dysfunction.
The condition is far more common in older adults, women, and people carrying multiple risk factors simultaneously. A diagnostic scoring system called the H2FPEF score captures this pattern well: it assigns points for obesity, use of two or more blood pressure medications, atrial fibrillation, elevated pressure in the lung arteries, age over 60, and signs of high filling pressure on an echocardiogram. A score of 6 or higher out of 9 corresponds to a greater than 90% probability of diastolic heart failure.
How It’s Diagnosed
Because the heart’s pumping strength looks normal, diastolic heart failure can be easy to miss. An echocardiogram (ultrasound of the heart) is the primary tool. It measures ejection fraction, which will be 50% or above, and also evaluates how well the heart relaxes and fills. Specific measurements of how fast the heart wall moves during filling, and how much pressure builds up inside the chamber, help confirm the diagnosis.
Blood tests for natriuretic peptides, hormones released when the heart is under stress, are part of the diagnostic workup. These levels help distinguish heart failure from other causes of shortness of breath, though they tend to be lower in diastolic heart failure than in systolic heart failure, which can sometimes cause confusion. When standard tests are inconclusive, exercise stress testing with echocardiography can reveal filling problems that only appear during physical activity.
Treatment and What to Expect
For years, diastolic heart failure was the harder type to treat. Most classic heart failure medications were developed for systolic failure and showed limited benefit in patients whose pumping function was normal. That changed with the introduction of SGLT2 inhibitors, a class of drugs originally designed for diabetes. In clinical trials, these medications significantly reduced hospitalizations for heart failure and cardiovascular death in patients with preserved ejection fraction. They also slowed kidney function decline and improved quality of life, addressing two of the biggest concerns patients face.
Part of how these drugs work is by reducing inflammation and oxidative stress in heart muscle cells, targeting mechanisms that directly contribute to the stiffening process. They also have a notable effect on fluid management: patients taking them are less likely to need increased doses of diuretics (water pills) and more likely to have their diuretic doses reduced over time. Another medication that combines two blood pressure drugs in one pill has shown benefits in reducing the need for new diuretic prescriptions.
Beyond medications, managing the underlying conditions is central to treatment. Controlling blood pressure, losing weight, treating sleep apnea, and managing blood sugar all directly reduce the stress on a stiffened heart. Exercise training, particularly moderate aerobic activity, has shown consistent benefits in improving exercise tolerance and quality of life in clinical studies. The goal is not to reverse the stiffness entirely but to reduce the burden on the heart and prevent the cycle of hospitalizations that defines advanced heart failure.
Long-Term Outlook
Diastolic heart failure carries a serious prognosis. In a large study of Medicare patients hospitalized with heart failure, five-year mortality was approximately 76% for diastolic heart failure, virtually identical to the rate for systolic heart failure. This finding surprises many people, since a “preserved” ejection fraction sounds reassuring. It is not. The similar mortality rates reflect the fact that diastolic heart failure tends to occur alongside many other serious conditions, and the heart failure itself progressively worsens over time.
Hospitalizations are a major part of the disease trajectory. Each hospitalization for fluid overload or worsening symptoms is associated with a further decline in function and quality of life. The pattern tends to be gradual, with periods of relative stability interrupted by episodes of decompensation, often triggered by missed medications, dietary salt excess, infections, or uncontrolled blood pressure. Recognizing early warning signs like sudden weight gain, worsening shortness of breath, or new ankle swelling allows for earlier intervention and can help avoid hospital stays.