During a patient's cardiovascular evaluation, you detect a high-pitched, scratchy, scraping cardiac sound that is synchronous with the heartbeat while performing auscultation with the diaphragm of the stethoscope. The sound is heard best when the patient is leaning forward and holding their breath after expiration. Which potential finding is most accurately described by these characteristics?
Third heart sound (S3)
Aortic ejection click
Mitral valve prolapse
Pericardial friction rub