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. Abstract: 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.
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