title: The third heart sound.
abstract: BACKGROUND
  In the current era of cost-effective delivery of health care, it is particularly timely to carefully reevaluate the clinical utility of selected physical signs. The third heart sound (S3) is one such sign that is the focus of the current review.
  
  
  METHODS
  I conducted a computerized MEDLINE search of articles related to S3 published since 1966. For information before 1966, textbook and other cross-references from MEDLINE-identified sources were used.
  
  
  RESULTS
  The presence of S3 may be the earliest clue to the presence of left ventricular failure. It predicts a high risk of postoperative complications in the setting of noncardiac surgery and is a predictor of response to digoxin in patients with congestive heart failure. However, the interobserver variation in its detection is high even among experienced clinicians.
  
  
  CONCLUSIONS
  While the presence of S3 may have important clinical implications, high interobserver variation in detection limits its use.
authors.affiliation: Section of General Internal Medicine, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033, USA.
authors.forename: N
authors.initials: N
authors.lastname: Joshi
mesh_terms: D000328:Adult; D002648:Child; D006331:Heart Diseases / Q000175:diagnosis*; D006333:Heart Failure / Q000175:diagnosis; D006347:Heart Sounds; D006801:Humans; D015588:Observer Variation; D011237:Predictive Value of Tests