AUTHOR=Fujiyoshi Kazuhiro , Yamaoka-Tojo Minako , Fujiyoshi Kanako , Komatsu Takumi , Oikawa Jun , Kashino Kunio , Tomoike Hitonobu , Ako Junya 

TITLE=Beat-to-beat alterations of acoustic intensity and frequency at the maximum power of heart sounds are associated with NT-proBNP levels

JOURNAL=Frontiers in Cardiovascular Medicine

VOLUME=Volume 11 - 2024

YEAR=2024

URL=https://www.frontiersin.org/journals/cardiovascular-medicine/articles/10.3389/fcvm.2024.1372543

DOI=10.3389/fcvm.2024.1372543

ISSN=2297-055X

ABSTRACT=Background: Auscultatory features of heart sounds (HS) in patients with heart failure (HF) had been studied intensively. Recent developments of digital as well as electrical devices for auscultation provided easy listening chances to recognize peculiar sounds related to the diastolic heart sounds such as S3 or S4. We sought to assess HS quantitatively by acoustic measures of intensity (dB) and audio frequency (Hz).
Methods: Consecutive forty patients aged between 46 and 87 years (mean, 74 years) with chronic cardiovascular disease (CVD) were enrolled in the present study with the written informed consent when they visited the Kitasato University Outpatient Clinic. HS were recorded at the fourth intercostal space along the left sternal border using a highly sensitive digital device. Consecutive two heart beats were quantified on sound intensity (dB) and audio frequency (Hz) at the peak power of each spectrogram of S1~S4 by an audio editing and recording application software. The participants were classified into the absence of HF (n=27), HF (n=8), and high-risk HF (n=5), referencing to the levels of NT-proBNP < 300, ≥ 300 and ≥ 900 pg/mL, respectively and also to the levels of ejection fraction (EF), such as preserved EF (n=22), mildly reduced EF (n=12), and reduced EF (n=6).
Results: The intensities of four components of HS (S1~S4) decreased linearly (p < 0.02 ~ 0.001) with levels of body mass index (BMI) (range 16.2 – 33.0 kg/m2). Differences of S1 intensity (ΔS1) and its frequency (ΔfS1) between consecutive two beats were non-audible level and were larger in cases with HF than non-HF CVD (ΔS1, r = 0.356, p = 0.024; ΔfS1, r = 0.356, p = 0.024). The cut-off values of ΔS1 and ΔfS1 for discriminating the presence of high-risk HF were 4.0 dB and 5.0 Hz, respectively.
Conclusions: Despite significant attenuations of all four components of HS by BMI, beat-to-beat alterations of both intensity and frequency of S1 were associated with the severity of HF. Acoustic quantification of HS enabled analyses of sounds below the audible level, and the sound analysis might provide an early sign of HF.