Systolic (HFrEF) vs Diastolic (HFpEF) Heart Failure: How to Tell Them Apart
HFrEF and HFpEF are two expressions of the same clinical syndrome—dyspnea, fatigue, and congestion from a failing heart—but they diverge on the central axis of ejection fraction and the underlying mechanical defect. HFrEF is a problem of impaired contraction with a dilated, poorly ejecting ventricle (EF ≤40%), while HFpEF is a problem of impaired relaxation and filling in a stiff ventricle that ejects normally (EF ≥50%). This distinction is not academic: it changes the echocardiographic picture, the exam findings, and—most importantly—the treatment that works.
How to tell them apart
| Feature | Systolic heart failure (HFrEF) | Diastolic heart failure (HFpEF) |
|---|---|---|
| Ejection fraction | Reduced, EF ≤40% | Preserved, EF ≥50% |
| Core mechanical defect | Impaired contraction (systolic dysfunction)—the ventricle cannot eject effectively | Impaired relaxation and filling (diastolic dysfunction)—the stiff ventricle cannot fill at low pressures |
| LV cavity and structure | Dilated LV, often with a displaced PMI | Normal or small LV cavity, often with LV hypertrophy |
| Gallop sound | S3 gallop, reflecting volume overload | S4 gallop, from atrial contraction into a stiff ventricle |
| Typical causes | Ischemic disease and dilated cardiomyopathy (idiopathic, viral, alcohol, familial, peripartum, drug-induced, tachycardia-mediated, infiltrative) | Hypertension, aging, obesity, and diabetes |
| Associated arrhythmia | Atrial fibrillation can occur but is not the defining association | Often atrial fibrillation, as the atria struggle against a stiff ventricle; loss of atrial kick is especially poorly tolerated |
| Evidence-based therapy | Four pillars—ARNI, beta-blocker, MRA, SGLT2 inhibitor—plus devices (ICD/CRT) when indicated, all with mortality benefit | Largely symptomatic: diuretics, SGLT2 inhibitors, and treatment of underlying conditions; most therapies have not shown a mortality benefit |
| Response to guideline therapy | LVEF can improve significantly with optimized medical therapy over months | Limited disease-modifying options; management targets symptoms and precipitants |
The reasoning
Anchor on ejection fraction from echocardiography—this is the single finding that classifies the patient (HFrEF ≤40% vs HFpEF ≥50%) and dictates therapy. Support the classification with structure and auscultation: a dilated ventricle with a displaced PMI and an S3 points to HFrEF, whereas a normal or small hypertrophied ventricle with an S4 points to HFpEF. Use the clinical context to predict the type before the echo confirms it: a hypertensive, older, obese, or diabetic patient—often with atrial fibrillation—fits HFpEF, while ischemic history or features of a dilated cardiomyopathy fit HFrEF. Because both share congestion and elevated BNP, resist using symptoms alone; let EF and ventricular structure arbitrate.
Key tests
- Echocardiography (the central test): defines LVEF (HFrEF ≤40% vs HFpEF ≥50%), shows a dilated LV with wall motion abnormalities in HFrEF versus a normal/small cavity with LV hypertrophy in HFpEF, and estimates filling pressures via the E/e' ratio.
- Natriuretic peptides (BNP): elevated in both and support the syndrome, but do not by themselves distinguish reduced from preserved EF.
- Coronary angiography: helps identify an ischemic cause in HFrEF; non-obstructive disease in a dilated, low-EF ventricle points toward a non-ischemic dilated cardiomyopathy rather than HFpEF.
What they share
- The heart failure syndrome itself: dyspnea, fatigue, and orthopnea plus signs of congestion and low output
- Elevated natriuretic peptides (BNP) supporting the diagnosis
- Elevated cardiac filling pressures
- Congestive findings such as elevated JVP, peripheral pitting edema, crackles, and pleural effusions (crackles may be absent in chronic HF as pulmonary lymphatics adapt)
- Diuretics for volume relief and SGLT2 inhibitors are used in both
- Both require echocardiography and a search for precipitants and underlying causes
Pitfalls
- Assuming clear lungs excludes heart failure—in chronic HF, adapted pulmonary lymphatic drainage can keep lungs clear despite markedly elevated filling pressures.
- Using BNP to distinguish HFrEF from HFpEF—it is elevated in both and confirms the syndrome, not the EF category.
- Applying HFrEF's four pillars to HFpEF expecting mortality benefit—most HFrEF-proven therapies have not shown mortality benefit in HFpEF, where treatment is largely symptomatic.
- Underestimating atrial fibrillation in HFpEF—loss of the atrial kick sharply reduces cardiac output when good LV filling is required, precipitating decompensation.
- Committing to an ICD too early in HFrEF—reassess LVEF after at least 3 months of optimized guideline-directed therapy, since the EF may improve above the device threshold.
Practice this the way the exam tests it — on branching cases where your decisions shape the patient.