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Acoustic Cardiography

Policy Number: MP-179

Latest Review Date:  September 2019

Category:  Medicine                                                  

Policy Grade:  Effective July 29, 2014: Active Policy but no longer scheduled for regular literature reviews and updates.

Description of Procedure or Service:

Correlated audio-electric cardiography describes the correlated display of EKG tracings and a visual display of the acoustic heart sounds, recorded from an acoustic sensor placed on the chest.  The recordings can then undergo computer analysis.  The Audicor system is a medical device that has received FDA approval through the 510(k) process specifically for correlated audio-electric cardiography.  According to the FDA label, the intended use is as follows:  “The Audicor Upgrade System, when used with Audicor Sensors in the V3 and V4 positions on the chest wall, is intended for use in acquiring, analyzing and reporting ECG and heart sounds (phonocardiograph) data and to provide interpretation of the data for consideration by physicians.”

Another device receiving a 510K approval is the Zargis Acoustic Cardioscan.  It is described as an electronic auscultatory device, intended to provide support to physicians in the evaluation of heart sounds in patients.  The product will acquire and record the acoustic signals of the heart and analyze these signals.  The analysis procedure will identify specific heart sounds that may be present.  Identified sounds include S1, S2, and suspected murmurs.  The device is indicated for use in a clinical setting, by a physician or by trained personnel who are acting on the orders of a licensed physician.  It is not intended as a sole means of diagnosis.  Interpretations of heart sounds offered by the Zargis Acoustic Cardioscan are only significant when used in conjunction with physician over-read as well as consideration of all other relevant patient data.  (FDA, Indications for Use).

Optimization of CRT therapy is usually done using Doppler echocardiography.  Optimization involves manipulation of the atrio-ventricular (AV) and interventricular (VV) pacer settings in order to maximize left ventricular (LV) filling and stroke volume. Some evidence has reported that optimization improves overall clinical benefit, but these data are not uniform. Also, the question of whether re-optimization should be performed following initial optimization is controversial, as is the timing of re-optimization if it is performed.


Acoustic cardiography is considered not medically necessary and investigational.

Correlated audio-electric cardiography is considered not medically necessary and investigational.

Key Points:

Ability to Diagnose Systolic Function

Michaels et al (2010) evaluated whether acoustic cardiography improved detection of S3 and S4 in 90 patients referred for angiography. A total of 35 subjects at various levels of clinical experience, from medical student to attending, listened to recordings of each patient’s heart sounds using auscultation alone, and then using both auscultation and acoustic cardiography. The gold standard for the presence or absence of heart sounds was the consensus of two experienced readers who were blinded to other aspects of the study.

There was improvement in the ability to detect S3 in each cohort of clinical training, with overall accuracy improving by between 2-18%. The improvement in accuracy was statistically significant for more experienced trainees but not for medical students. For example, using auscultation alone, residents detected an S3 correctly in 68% of patients. This improved to 85% when auscultation was combined with acoustic cardiography. For attending physicians, the accuracy of S3 detection was 72% with auscultation alone, and this was improved to 80% (p<0.01) with the addition of acoustic cardiography.

In a study by Maisel et al (2010), the predictive ability of acoustic cardiography was evaluated for acute heart failure in 995 patients greater than 40 years old who presented to the emergency department (ED) with dyspnea. The main parameter used was the strength of the S3 sound graded on a 0-10 scale. The gold standard for the diagnosis of acute heart failure (AHF) was consensus by two cardiologists who were blinded to the results of acoustic cardiography. For the entire population, the S3 strength was predictive of AHF in univariate analysis but was not an independent predictor in multivariate analysis. For the subpopulation of patients who were labeled as ‘gray zone’ patients based on an intermediate level of BNP (100-499 pg/mL), the information from acoustic cardiography improved the diagnostic accuracy of AHF from 47-69%. Obese patients (body mass index [BMI] >30), in whom auscultation is often more difficult, was also a potentially problematic subgroup. In this population, the sensitivity of S3 detection improved from 14-28% with the addition of acoustic cardiography, but the specificity decreased from 99-88%.

Wang et al (2012) evaluated the ability of acoustic cardiography to distinguish between patients who had heart failure with systolic dysfunction (n=89), heart failure with normal systolic function (n=94), and hypertension without clinical heart failure (n=109). All patients underwent acoustic cardiography and echocardiography, and the diagnostic accuracy of acoustic cardiography was compared to echocardiography. For distinguishing patients with hypertension from patients with heart failure and normal systolic function, the sensitivity of acoustic cardiography was 55%, the specificity was 90%, and the area under the curve was 0.83. For distinguishing heart failure and normal systolic function from heart failure with systolic dysfunction, the sensitivity of acoustic cardiography was 53%, the specificity was 91% and the area under the curve was 0.81. These values were not significantly different from echocardiography for any of the measures reported.

Wang et al (2013) evaluated the ability of acoustic cardiography to identify severe systolic dysfunction (left ventricular ejection fraction [LVEF], ≤35%) and/or severe diastolic dysfunction (presence of a restrictive LV filling pattern) in patients with heart failure with reduced ejection fraction. The study included 127 adult inpatients with heart failure with reduced ejection fraction. All patients underwent acoustic cardiography and echocardiography, and the diagnostic accuracy of acoustic cardiography was compared with echocardiography. The authors used a Systolic Dysfunction Index (SDI) to quantify systolic dysfunction on acoustic cardiography. The SDI was based on S3 score, QRS duration, QR interval, and percent EMAT and was mapped onto a scale of 0 to 10, where an SDI greater than 5 indicates an LVEF less than 50%, and an SDI greater than 7.5 indicates an LVEF less than 35% and elevated LV filling pressure. An SDI greater than 5 was the best predictor to discriminate patients with LVEF less than or equal to 35% from those with moderate systolic dysfunction (LVEF between 35% and 50%), associated with an AUC of 0.79 (95% confidence interval [CI], 0.71 to 0.87), with sensitivity of 87% and specificity of 60%. For the subgroup of 122 patients with diastolic dysfunction, an S3 score greater than 4 best predicted a restrictive filling patter, associated with an AUC of 0.76 (95% CI, 0.67 to 0.84), with sensitivity of 81% and specificity of 55%.

Toggweiler et al (2013) reported results of a prospective cohort study to evaluate the role of acoustic cardiography in follow-up for left ventricular function among patients who had undergone an anthracycline-containing chemotherapy regimen. The study included 187 patients who had undergone anthracycline treatment for a variety of cancers at a single institution. At baseline, at completion of anthracycline-containing chemotherapy, and at long-term follow up, patients underwent evaluation with echocardiography and acoustic cardiography. Left ventricular function was evaluated with acoustic cardiography using EMAT values. Over a mean follow-up of 3.8 years, the mean LVEF, measured by echocardiography, decreased from 64% at baseline to 61% postchemotherapy (p<0.001) and remained at 61% at late follow up (p<0.01 vs baseline). Mean EMAT increased from 80 ms at baseline to 84 postchemotherapy (p<0.01), and increased to 89 at late follow-up (p<0.01 vs baseline). The relative percent change in EMAT correlated with relative changes in the LVEF (r=-0.33, p<0.01). Eight patients (4%) developed systolic dysfunction. A percent change in EMAT of greater than 12.4% after chemotherapy had a sensitivity and specificity of 88% and 85%, respectively, for identifying patients with systolic dysfunction. The authors recommend the use of acoustic cardiography for monitoring patients based on the high sensitivity and specificity for identifying systolic dysfunction. However, this study is limited by relatively small size, single-center design, and a limited number of cancer diagnoses that were included, which makes generalizing the results to wider patient care difficult.

Chan et al (2013) evaluated the role of acoustic cardiography in the evaluation of the severity of pulmonary arterial hypertension (PAH) in a prospective case-control study of 40 cases with PAH and 130 controls without clinical or hemodynamic evidence of PAH. The intensity (measured by peak-to-peak amplitude and expressed in mV) and complexity (measured as a dimensionless index based on spectral analysis) of S1 and S2 were evaluated. Patients with PAH were found to have significantly greater S2 complexity compared with controls (p<0.001 for both lead V3 and V4 position); S2 complexity was associated with mean pulmonary artery pressure among patients with PAH (r=0.55, p<0.001). The clinical implications of these findings are not well-defined.

Optimization of Cardiac Resynchronization Therapy (CRT)

Taha et al (2010) evaluated the correlation of acoustic cardiography with echocardiography for optimization of CRT settings, using the parameter of S3 signal strength rather than EMAT. There was a high correlation between the two parameters for optimization of AV delay (r=0.86, p<0.001) and a somewhat lower correlation for optimization of VV delay (r=0.64, p<0.001). For VV delay, the optimal intervals were identical in 56% of patients, and for VV delay the optimal intervals were identical in 75% of patients.

Ability to Detect Coronary Artery Disease

In 2018, Thomas et al. evaluated the CADence device in the acoustic detection of coronary artery disease on patients with chest pain and CAD risk factors undergoing nuclear stress tests. The trial was designed to demonstrate non-inferiority of the acoustic device for diagnostic accuracy in detecting significant CAD compared to an objective performance criteria for nuclear stress testing.  The acoustic device had 78% sensitivity (non-inferior), but only 35% specificity (failure to demonstrate non-inferiority).

In 2016, Azimpour et al. evaluated the performance of acoustic detection of intracoronary murmurs related to coronary artery stenosis in patients undergoing comparative coronary angiography. A total of 123 patients were analyzed. Acoustic detection sensitivity for stenosis was 70% and specificity was 80%.  It is noted that detection of multivessel CAD gave a lower accuracy. Limitations include study size and inconclusive samples.  The authors conclude by stating , “further investigation is warranted to compare the clinical performance of this modality with current noninvasive approaches that evaluate patients at risk for atherosclerotic and obstructive coronary artery disease.”

Summary of Evidence

A number of published articles support that acoustic cardiography improves the detection of an S3 compared to auscultation alone. However, there is no evidence that acoustic cardiography contributes independent predictive information when combined with standard clinical workup for heart failure such as physical exam findings, laboratory testing, and routine imaging studies. In order to demonstrate an incremental benefit in the diagnosis of heart failure, the improvement in diagnostic accuracy with and without acoustic cardiography must be in the context of the entire spectrum of clinical information collected routinely in the workup of a patient with suspected heart failure. For example, two studies report that acoustic cardiography improves the accuracy of heart failure diagnosis for patients with a “gray zone” BNP. However, a gray zone BNP does not necessarily mean the diagnosis of heart failure is uncertain when all clinical information is considered; therefore, this type of evidence is not sufficient to conclude that acoustic cardiography improves the diagnosis of heart failure.

When used to optimize CRT settings, several studies report that acoustic cardiography has a high correlation with Doppler echocardiography. No studies have demonstrated that acoustic cardiography is superior to echocardiography for this purpose; therefore, acoustic cardiography when used for optimization of CRT therapy is considered investigational.

There is a lack of evidence for utilizing acoustic cardiography for detecting CAD.  The current studies are small and with potential bias. One study failed to show non-inferiority and other studies have been inconclusive.  Acoustic cardiography for detecting CAD is considered investigational.

Key Words:

Acoustic heart sound recording, correlated audioelectric cardiography, Audicor

Approved by Governing Bodies:

Audicor received 510(k) approval from the FDA on November 3, 2003

Zargis Acoustic Cardioscan (ZAC) received 510k clearance in May 2004.

Audicor 200 System was received a 510(k) clearance January 15, 2007

CADence received 510k clearance in August 2017.

Benefit Application:

Coverage is subject to member’s specific benefits.  Group specific policy will supersede this policy when applicable.

ITS: Home Policy provisions apply

FEP contracts: FEP does not consider investigational if FDA approved and will be reviewed for medical necessity. Special benefit consideration may apply.  Refer to member’s benefit plan.

Current Coding: 

CPT codes:


Unlisted cardiovascular service or procedure

Previous Coding: 


Acoustic cardiography, including automated analysis of combined acoustic and electrical intervals; single, with interpretation and report (Code deleted effective January 1, 2016)


Multiple, including serial trended analysis and limited reprogramming of device parameter – AV or VV delays only, with interpretation and report (Code deleted effective January 1, 2016)


Multiple, including serial trended analysis and limited reprogramming of device parameter – AV and VV delays, with interpretation and report (Code deleted effective January 1, 2016)


  1. Arand P, Burton D, Myers R, et al.  Diagnostic performance of a computerized algorithm for augmenting the ECG with acoustical data. J Electrocardiol 2003; 36 Suppl: 169.

  2. Azimpour F, Caldwell E, Tawfik P, et al. Audible Coronary Artery Stenosis. Am J Med. 2016 May;129 (5):515-521.

  3. Bertini M, Delgado V, Bax JJ et al. Why, how and when do we need to optimize the setting of cardiac resynchronization therapy? Europace 2009; 11:v46-57.

  4. Blue Cross Blue Shield Association. Correlated Audioelectric Cardiography.  Medical Policy Reference Manual, September 2008.

  5. Chan W, Woldeyohannes M, Colman R et al. Haemodynamic and structural correlates of the first and second heart sounds in pulmonary arterial hypertension: an acoustic cardiography cohort study. BMJ Open 2013; 3(4).

  6. Collins Sean P, Lindsell Christopher J, et al.  The effect of treatment on the presence of abnormal heart sounds in emergency department patients with heart failure.  American Journal of Emergency Medicine 2006; 24: 25-32.

  7. Erne P. Beyond auscultation – acoustic cardiography in the diagnosis and assessment of cardiac disease. Swiss Med Wkly 2008; 138:439-52.

  8. FDA. Audiocor System. Available at:

  9. FDA. CADence System.  Available at:

  10. FDA. Zargis Acoustic Cardioscan. Available at:

  11. Hasan A, Abraham WT, Quinn-Tate L et al. Optimization of cardiac resynchronization devices using acoustic cardiography: a comparison to echocardiography. Congest Heart Fail, 2006; 12(suppl 1):25-31.

  12. Kobza R, Roos M, Toggweiler S, et al.  Recorded heart sounds for identification of ventricular tachycardia.  Resuscitation, November 2008; 79(2): 265-272.

  13. Kosmicki DL, Collins SP, Kontos MC et al. Noninvasive prediction of left ventricular systolic dysfunction in patients with clinically suspected heart failure using acoustic cardiography. Congest Heart Fail 2010; 16:249-53.

  14. Maisel AS, Peacock WF, Shah KS et al. Acoustic cardiography S3 detection use in problematic subgroups and B-type natriuretic peptide “gray zone”: secondary results from the Heart failure and Audicor technology for Rapid Diagnosis and Initial Treatment Multinational Investigation. Am J Emerg Med July 12, 2010. [Epub ahead of print]

  15. Michaels AD, Khan FU, Moyers B. Experienced clinicians improve detection of third and fourth heart sounds by viewing acoustic cardiography. Clin Cardiol 2010; 33:E36-E42.

  16. Moyers B, Shapiro M, Marcus GM, et al.  Performance of phonoelectrocardiographic left ventricular systolic time intervals and B-type natriuretic peptide levels in the diagnosis of left ventricular dysfunction.  Ann Noninvasive Electrocardiol, April 2007; 12(2): 89-97.

  17. Taha N, Zhang J, Ranjan R et al. Biventricular pacemaker optimization guided by comprehensive echocardiography-preliminary observations regarding the effects on systolic and diastolic ventricular function and third heart sound. J Am Soc Echocardiogr 2010; 23:857-66.

  18. Tavel Morton E and Katz Hart.  Usefulness of a new sound spectral averaging technique to distinguish an innocent systolic murmur from that of aortic stenosis.  American Journal of Cardiology, April 2005, Vol. 95, pp. 902-904.

  19. Thomas JL, Ridner M, Cole JH, et al. The clinical evaluation of the CADence device in the acoustic detection of coronary artery disease. Int J Cardiovasc Imaging. 2018 Dec; 34(12):1841-1848.

  20. Toggweiler S, Odermatt Y, Brauchlin A et al. The clinical value of echocardiography and acoustic cardiography to monitor patients undergoing anthracycline chemotherapy. Clin Cardiol 2013; 36(4):201-6.

  21. Toggweiler S, Zuber M, Kobza R et al. Improved response to cardiac resynchronization therapy through optimization of atrioventricular and interventricular delays using acoustic cardiography: a pilot study. J Card Fail 2007; 13:637-42.

  22. U.S. Food and Drug Administration (FDA).  Zargis Acoustic Cardioscan (ZAC).  510(k) Summary of Safety and Effectiveness.

  23. Wang S, Fang F, Liu M et al. Rapid bedside identification of high-risk population in heart failure with reduced ejection fraction by acoustic cardiography. Int J Cardiol 2013; 168(3):1881-6.

  24. Wang S, Lam YY, Liu M et al. Acoustic cardiography helps to identify heart failure and its phenotypes. Int J Cardiol 2012. [Epub ahead of print]

  25. Yancy CW, Jessup M, Bozkurt B et al. 2013 ACCF/AHA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation 2013; 128(16):e240-e327.

  26. Zuber M, Erne P. Acoustic cardiography to improve detection of coronary artery disease with stress testing. World J Cardiol. 2010 May 26;2(5):118-24.

  27. Zuber M, Toggweiler S, Quinn-Tate L et al. A comparison of acoustic cardiography and echocardiography for optimizing pacemaker settings in cardiac resynchronization therapy. Pacing Clin Electrophysiol 2008; 31:802-11.

  28. Zuber M, Toggweiler S, Roos M et al. Comparison of different approaches for optimization of atrioventricular and interventricular delay in biventricular pacing. Europace, 2008; 10:367-73.

Policy History:

Medical Policy Group, June 2004 (3)

Medical Policy Administration Committee, September 2004

Available for comment September 7-October 21, 2004

Medical Policy Group, June 2005 (1)

Medical Policy Group, June 2006 (1)

Medical Policy Group, June 2007 (1)

Medical Policy Group, June 2009 (1)

Medical Policy Group, June 2011 (3); Updated Description, Policy, Key Points, & References

Medical Policy Administration Committee, July 2011

Available for comment July 6 through August 22, 2011

Medical Policy Group, June 2012 (3); 2012 Updates to Key Points and References

Medical Policy Group, August 2013 (4): 2013 Updates. No changes.

Medical Policy Panel, June 2014 

Medical Policy Group, June 214 (4): Updated Key Points and References. No changes to the policy statement at this time.  Policy inactive effective July 29, 2014.

Medical Policy Group, November 2015: 2016 Annual Coding Update. Moved cpt codes 0223T, 0224T, and 0225T to previous coding section.

Medical Policy Group, September 2019 (4):  Updates to Description, Key Points, Approved by Governing Bodies, References and Previous Coding.  Removed cpt codes 0068T – 0070T, deleted effective 1/2010.

This medical policy is not an authorization, certification, explanation of benefits, or a contract. Eligibility and benefits are determined on a case-by-case basis according to the terms of the member’s plan in effect as of the date services are rendered. All medical policies are based on (i) research of current medical literature and (ii) review of common medical practices in the treatment and diagnosis of disease as of the date hereof. Physicians and other providers are solely responsible for all aspects of medical care and treatment, including the type, quality, and levels of care and treatment.

This policy is intended to be used for adjudication of claims (including pre-admission certification, pre-determinations, and pre-procedure review) in Blue Cross and Blue Shield’s administration of plan contracts.

The plan does not approve or deny procedures, services, testing, or equipment for our members. Our decisions concern coverage only. The decision of whether or not to have a certain test, treatment or procedure is one made between the physician and his/her patient. The plan administers benefits based on the member’s contract and corporate medical policies. Physicians should always exercise their best medical judgment in providing the care they feel is most appropriate for their patients. Needed care should not be delayed or refused because of a coverage determination.

As a general rule, benefits are payable under health plans only in cases of medical necessity and only if services or supplies are not investigational, provided the customer group contracts have such coverage.

The following Association Technology Evaluation Criteria must be met for a service/supply to be considered for coverage:

1. The technology must have final approval from the appropriate government regulatory bodies;

2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes;

3. The technology must improve the net health outcome;

4. The technology must be as beneficial as any established alternatives;

5. The improvement must be attainable outside the investigational setting.

Medical Necessity means that health care services (e.g., procedures, treatments, supplies, devices, equipment, facilities or drugs) that a physician, exercising prudent clinical judgment, would provide to a patient for the purpose of preventing, evaluating, diagnosing or treating an illness, injury or disease or its symptoms, and that are:

1. In accordance with generally accepted standards of medical practice; and

2. Clinically appropriate in terms of type, frequency, extent, site and duration and considered effective for the patient’s illness, injury or disease; and

3. Not primarily for the convenience of the patient, physician or other health care provider; and

4. Not more costly than an alternative service or sequence of services at least as likely to produce equivalent therapeutic or diagnostic results as to the diagnosis or treatment of that patient’s illness, injury or disease.