Association between phonocardiographic third and fourth heart sounds and objective measures of left ventricular function

Context  The third (S₃) and fourth (S₄) heart sounds detected by phonocardiography are considered to represent the criterion standards of the gallop sounds, but their test characteristics have not been explored. Objective  To determine the diagnostic test characteristics of the S₃ and S₄ for prediction of left ventricular dysfunction using a computerized heart sound detection algorithm. Design, Setting, and Participants  Prospective study of 90 adult patients undergoing elective left-sided heart catheterization at a single US teaching hospital between August 2003 and June 2004. The mean age was 62 (SD, 13) years (range, 24-90 years) and 61 (68%) were male. Within a 4-hour period, participants underwent computerized heart sound phonocardiographic analysis, cardiac catheterization, transthoracic echocardiography, and blood sampling for assessment of an S₃/S₄, left ventricular end-diastolic pressure (LVEDP), left ventricular ejection fraction (LVEF), and B-type natriuretic peptide (BNP), respectively. Main Outcome Measures  Diagnostic test characteristics of the computerized phonocardiographic S₃ and S₄ using markers of left ventricular function as criterion standards. Results  Mean (SD) LVEDP was significantly elevated (18.4 6.9] mm Hg vs 12.1 7.3] mm Hg; P<.001), mean (SD) LVEF was reduced (49.4% 20.2%] vs 63.6% 14.8%]; P<.001), and median (interquartile range) BNP was elevated (330 98-1155] pg/mL vs 86 41-192] pg/mL; P<.001) in those with an S₃, S₄, or both compared with patients without a diastolic heart sound. The sensitivities of these heart sounds to detect an elevated LVEDP, reduced LVEF, or elevated BNP were 41%, 52%, and 32% for an S₃, and 46%, 43%, and 40% for an S₄, respectively. For abnormal levels of the same markers of ventricular function, the specificities of the S₃ were 92%, 87%, and 92%, while the specificities of the S₄ were 80%, 72%, and 78%, respectively. Conclusions  Neither the phonocardiographic S₃ nor the S₄ is a sensitive marker of left ventricular dysfunction. The phonocardiographic S₃ is specific for left ventricular dysfunction and appears to be superior to the moderate specificity of the phonocardiographic S₄.