A 58-year-old man with dilated cardiomyopathy presents with progressive dyspnea and orthopnea. His echocardiogram shows LVEF 28% with global hypokinesis. Which single feature best distinguishes systolic heart failure from diastolic heart failure in this patient?

Explanation

## Systolic vs. Diastolic Heart Failure: Key Discriminator ### Pathophysiologic Distinction **Key Point:** Reduced left ventricular ejection fraction (LVEF ≤40%) is the cardinal and defining feature that distinguishes systolic heart failure from diastolic heart failure. This is the gold-standard criterion used in all major guidelines (ACC/AHA, ESC) to classify heart failure phenotype. ### Comparison Table | Feature | Systolic HF | Diastolic HF | | --- | --- | --- | | **LVEF** | ≤40% (defining) | ≥50% (normal or near-normal) | | **Pathology** | Contractile dysfunction | Impaired relaxation/compliance | | **PCWP elevation** | Present | Present | | **S3 gallop** | Common | Uncommon | | **BNP elevation** | Marked | Variable | | **Echocardiography** | Global hypokinesis, chamber dilation | Normal LV size, wall thickening | ### Why LVEF is the Discriminator **High-Yield:** All other features—elevated PCWP, S3, elevated natriuretic peptides—occur in BOTH systolic and diastolic heart failure. LVEF is the ONLY finding that segregates the two phenotypes reliably. **Clinical Pearl:** In this case, the patient's LVEF of 28% immediately classifies him as systolic HF (HFrEF). If his LVEF were ≥50% with the same symptoms and elevated PCWP, he would have diastolic HF (HFpEF). ### Mechanism 1. **Systolic HF (HFrEF):** Loss of contractile force → reduced stroke volume → LVEF drops 2. **Diastolic HF (HFpEF):** Stiff ventricle → impaired early filling → normal LVEF but elevated filling pressures **Warning:** Do not confuse elevated PCWP or BNP with the discriminator—both are elevated in both types. The distinguishing feature is the contractile function itself, reflected in LVEF.