Development of an Algorithm to Differentiate Heart Murmurs Using Electronic Stethoscopes
Development of an Algorithm to Differentiate Heart Murmurs Using Electronic Stethoscopes
The Eko CORE and DUO stethoscopes are FDA-approved electronic devices that have the capacity
 to record heart sounds. The study seeks to expand murmur detection to include VHD
 classification through the development of novel ML algorithms that are able to distinguish
 between systolic vs. diastolic vs. continuous murmurs, as well as classify VHD type and
 severity, using 4-point auscultation with Eko CORE and DUO electronic stethoscopes to record
 heart sounds.
Valvular heart disease (VHD), a subclass of structural heart disease (SHD), is a major cause
 of mortality and reduced quality of life for tens of millions of patients worldwide.
 Detecting VHD early allows the disease to be carefully monitored so that surgery can be
 considered as soon as the stenosis progresses to severe. Unfortunately, it is difficult for
 many clinicians to accurately identify VHD in its early stages and assess its severity
 through physical examination alone. This difficulty stems from both the subtlety of symptoms
 associated with VHD, and from clinicians' inability to reliably detect the heart murmurs
 indicative of VHD using a traditional stethoscope, particularly in the noisy and rushed
 environments characteristic of many healthcare settings.

 AS, mitral regurgitation (MR), and tricuspid regurgitation (TR) all result in reliably
 reproducible auscultatory findings. Yet despite this, auscultation as a diagnostic procedure
 is notoriously poor: its accuracy to detect AS, MR, and TR ranges only from 5-40%. In
 addition, diastolic and continuous murmurs, which are rarer than the systolic murmurs caused
 by AS, MR and TR, and almost always pathologic, are usually very difficult to detect by
 frontline clinicians. Diastolic murmurs are typically caused by VHD such as aortic
 regurgitation (AR), pulmonic regurgitation (PR), mitral stenosis (MS), or tricuspid stenosis
 (TS), and continuous murmurs are typically caused by non-valvular forms of SHD, such as
 congenital aortopulmonary window, shunts, and patent ductus arteriosus (PDA). Missing one of
 these murmurs could lead to significantly delayed diagnosis and care.

 Because of how difficult it is for clinicians to reliably screen for SHD through history
 taking and physical examination, the diagnosis of SHD relies heavily on echocardiography
 (echos), which is accepted as the gold standard for diagnosis of SHD severity by the
 cardiology community. The consequence of this is several-fold. First, many patients receive
 echos that would not be necessary if better screening and assessment tools existed. Second,
 echocardiography makes up a disproportionately large segment of healthcare expenditure.
 Third, patients are burdened with the responsibility of getting repeated echos due to the
 lack of better screening tools. The emotional, physical, and financial burden that
 accompanies such excessive testing, especially for patients living in underserved
 communities, cannot be overstated.

 Overall, there is a growing need for better preliminary screening tools that would identify
 these conditions, even when asymptomatic, early on and more consistently, to a degree of
 accuracy comparable to gold standard echocardiography. Such a tool would improve clinicians'
 confidence in their assessment during physical exams, which would enable them to help their
 patients make informed care decisions, offer disease-altering therapies, and at the same time
 reduce the reliance on, and frequency of, unnecessary and expensive auxiliary workups.
 Lastly, by facilitating early detection of VHD, morbidity and mortality rates would be
 expected to decrease due to earlier intervention.

 The FDA-approved Eko CORE and Eko DUO electronic stethoscopes offer clinicians a familiar and
 inexpensive tool that is widely accepted by patients, while at the same time offer sensors
 and technology that can improve screening and detection of medical conditions such as valve
 disease, as compared to auscultation with the traditional stethoscope. Both CORE and DUO
 feature sound amplification during auscultation, which improves the ability for the clinician
 to detect nuanced changes in heart sounds and patterns. The CORE allows recording of the
 audio to produce a phonocardiogram (PCG), while the DUO is able to record audio to produce a
 PCG as well as simultaneous recording of a single-lead electrocardiogram (ECG). Both devices
 use Bluetooth to wirelessly transmit PCG and ECG data to the Eko mobile application, which
 allows clinicians to visualize PCG and ECG as they auscultate, as well as to playback heart
 sound recordings, annotate notes on recorded audio, and save and share recordings. These
 features uniquely situate Eko electronic stethoscopes to be highly effective as preliminary
 screening tools in clinical practice.

 Eko Devices has developed and received 510(k) FDA approval for a machine-learning (ML)
 algorithm that can detect the presence or absence of heart murmur in adult patients with VHD,
 using either the Eko CORE or DUO electronic stethoscopes to record heart sounds. This
 algorithm was built using a deep neural network model trained on 5,878 PCG recordings
 collected on Eko CORE and Eko DUO from over 5,318 unique patients to classify heart sound
 recordings as containing a heart murmur or containing no audible murmur, and to discriminate
 good quality heart sound recordings from poor quality heart sound recordings. The trained
 model has been independently validated in a multi-site clinical study that enrolled 681 VHD
 patients with matched gold-standard echocardiograms. FDA approval was received in January
 2020.

 The present study seeks to expand murmur detection to include VHD classification through the
 development of novel ML algorithms that are able to distinguish between systolic vs.
 diastolic vs. continuous murmurs, as well as classify VHD type and severity, using 4-point
 auscultation with Eko CORE and DUO electronic stethoscopes to record heart sounds. These new
 algorithms will integrate the time-synchronized ECG streams from DUO to improve distinction
 between S1 and S2 heart sounds and improve performance of identifying systolic vs. diastolic
 time intervals. When combined with the FDA-approved algorithm for signal quality and murmur
 detection, these new algorithms will enable clinicians to have a complete VHD decision
 support system, as based on ACC/AHA Patient Management Guidelines, when using Eko
 stethoscopes in their clinical practice.20 This will arm clinicians with information to help
 them detect SHD early, make clinical care decisions with confidence and consistency, and
 improve overall patient outcomes while decreasing cost and increasing efficiency.
Inclusion Criteria:

 1. Adults aged 18 years and older

 2. Patient or patient's legal healthcare proxy consents to participation

 3. Have an audible heart murmur in at least one auscultation position, as heard by a
 clinician

 4. Undergoing or have undergone a complete (i.e., not limited) echocardiogram

 5. Willing to have heart recordings done with two different electronic stethoscopes

 Exclusion Criteria:

 1. Patient or proxy is unwilling or unable to give written informed consent

 2. Unable to complete a full clinical echocardiogram

 3. No audible heart murmur in at least one auscultation position, as heard by a clinician

 4. Experiencing a known or suspected acute cardiac event

 5. Mechanical ventricular support (such as ECMO, LVAD, RVAD, BiVAD, Impella, intra-aortic
 balloon pumps, TAH, VentrAssist, DuraHeart, HVAD, EVAHEART LVAS, HeartMate, Jarvik
 2000)

 6. Unwilling or unable to follow or complete study procedures