S4 is most characteristic of which heart failure type?

• A. Systolic CHF
• B. Right-sided CHF
• C. Diastolic CHF
• D. Normal aging

Answer: (C)

S4 is the atrial kick heard as a late diastolic sound, produced when the ventricle is stiff and noncompliant and the atrium contracts to push blood into it. This pattern points to diastolic dysfunction, where filling is impaired despite often preserved systolic function. In diastolic heart failure (heart failure with preserved ejection fraction), the ventricle’s reduced compliance from hypertrophy or other stiffening processes makes that late, forceful atrial contraction audible as S4.

S3, by contrast, comes from rapid filling into a dilated, failing ventricle and is more typical of systolic heart failure. Right-sided heart failure shows signs like elevated venous pressure, edema, and hepatomegaly rather than a characteristic S4. Normal aging can sometimes bring an S4 due to stiffening with age, but when the clinical context is heart failure, the association is strongest with diastolic dysfunction. Thus, S4 best indicates diastolic heart failure.