Heart's Sounds Could Help Diagnose Acute Heart Failure

A new technology called acoustic cardiography could help physicians diagnose cardiac disease and acute heart failure (AHF) in emergency department (ED) patients presenting with shortness of breath.

Researchers at the Veterans Affairs Health care System (San Diego, USA) conducted a secondary analysis of data from the 2006 HEart failure and Audicor technology for Rapid Diagnosis and Initial Treatment (HEARD-IT) multinational trial to determine if the strength of the S3 sound--an abnormal low-frequency, low-pitch sound in the heart's rhythm that is strongly related to AHF in certain subsets of patients--can provide diagnostic and prognostic information in problematic heart failure subgroups. To do so, dyspneic ED patients older than 40 years and not on dialysis were prospectively enrolled, and a blinded gold standard AHF diagnosis was determined by two cardiologists; the S3 strength parameter was delineated on a scale of 0-10.

The results showed that in the 995 patients enrolled, S3 strength served as a significant prognosticator in univariate analysis for adverse events, but not in a multivariable model. In patients with "gray zone" B-type natriuretic peptide (BNP) levels, acoustic cardiography increased diagnostic accuracy of AHF from 47% to 69%. The researchers concluded that S3 detection complements the use of BNP in the gray zone, and that its diagnostic and prognostic ability is largely unaffected by body mass index (BMI); in fact, acoustic cardiography improved S3 detection sensitivity in obese patients when compared to auscultation. The study was published ahead of print on July 12, 2010, in the American Journal of Emergency Medicine.

"We studied how measuring the presence of the S3 changed physicians' impressions of what was going on, how it potentially changed their workup and treatment for patients,” said lead author Sean Collins, M.D. "We need to get better at listening for the S3, and this study would suggest that if we don't hear it with our ears, that technology like this might be useful.”

BNP is a 32 amino acid polypeptide secreted by the ventricles of the heart in response to excessive stretching of heart muscle cells. There is a diagnostic "gray area,” often defined as values between 100 pg/mL and 500 pg/mL, for which the test is considered inconclusive for AHF; values above 500 pg/mL are generally considered to be positive.

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Veterans Affairs San Diego Health care System