Which of the following statements about the S3 heart sound is NOT correct?

The statement that the S3 heart sound can be a normal variant in those over age 40 is not correct. While the S3 sound, or "physiological third heart sound," can be observed in certain populations, it is more commonly associated with heart failure or volume overload rather than being considered a normal variant in older adults.

In younger individuals, particularly children and pregnant women, an S3 can be a normal finding due to increased blood flow conditions. However, once a person reaches the age of 40, the occurrence of an S3 sound may suggest underlying pathology, such as reduced ventricular compliance or heart failure. Therefore, in adults over 40, the presence of an S3 is often investigated further, rather than being regarded as a benign finding.

This context clarifies the nature of the S3 sound while distinguishing it as a clinical sign that warrants attention in older populations, rather than simply a normal variant.