It is common to hear an S3 after an acute heart attack. This usually disappears several days or weeks afterward. Persistent S3 after this time may mean more severe heart damage. In a study of patients awaiting heart transplant, an S3 was one of 7 risk factors predicting a poor prognosis.
Current ACC/AHA Guidelines recommend that patients with unstable angina and a concurrent auscultated
S3 be classified in the group at highest risk for adverse outcomes and considered candidates for an early invasive strategy. (Braunwald, E., Antman, E.M., Beasley, J.W., et al., ACC/AHA guideline update for the management of patients with unstable angina and non–ST-segment elevation myocardial infarction –2002/2006: summary article: a report of the American College of cardiology/American Heart Association Task Force on Practice Guidelines (Committee on the Management of Patients With Unstable Angina), Circulation )