Which heart sound is associated with heart failure in individuals over 35 years old?

The third heart sound (S3) is commonly associated with heart failure, especially in individuals over 35 years old. In the context of heart failure, S3 is indicative of increased ventricular filling pressures and is often heard in patients with volume overload conditions. It reflects rapid filling of the ventricles during diastole when blood from the atria enters the ventricles.

In older adults, the presence of an S3 sound can signal the development of heart failure, particularly when it is heard alongside other physical findings. This sound is sometimes referred to as a "gallop," and while it can be a normal finding in young athletes or pregnant women, it is generally abnormal in older adults and suggests deterioration in cardiac function.

In contrast, S1 and S2 are normal heart sounds that correspond to the closure of heart valves during the cardiac cycle. S4, known as an atrial sound, is associated with conditions like left ventricular hypertrophy or stiff ventricles often seen in long-standing hypertension but is not specifically tied to heart failure. Thus, the presence of S3 serves as a significant indicator of heart failure in individuals over 35.