COST MODEL FOR A NEW ACOUSTIC DIAGNOSTIC AID TO RULE OUT CORONARY ARTERY DISEASE

Winther S1, Böttcher M2, Wahler S3, Bolin K4

1Aarhus University Hospital, Aarhus N, Denmark,2Hjertemedicin Hjerteforskningsklinikken, Herning, Denmark,3St. Bernward GmbH, Hamburg, Germany,4University of Gothenburg, Gothenburg, Sweden

06.11.2017 1

• The technical and methodical principles of acoustic diagnosing coronary heart disease (CAD)

• Cardiologic care system in Denmark

• Clinical evidence of the method

• Application of the cost model and results

06.11.2017 2

AGENDA

• The development of acoustics in CAD:

The technical and methodical principles of acoustic diagnosing coronary heart disease

Diagnosis of CAD using an electronic stethoscope

• As in other arteries a stenosis causes flow turbulence, which makes noise

• The sounds are weak, but detectable using advanced signal processing

Master thesis in 2005

(Claus Graff & Samuel Schmidt)

Stenosis in the coronary arteries

.

1967

Heart sounds and CAD murmurs

5

What you listens for today: Murmurs from defective heart valves

Noise from stenotic coronary arteries•Not audible in most cases •Up to 1000 times weaker than other heart sounds

1000 1500 2000 2500 3000 3500 4000-0.1

-0.05

0

0.05

0.1

Time (ms)

Am

plit

ude

Heart sound recording: Normal subject

1000 1500 2000 2500 3000 3500 4000-0.4

-0.2

0

0.2

0.4

Time (ms)

Am

plit

ude

Heart sound recording: Subject wiht systolic murmur

1000 1500 2000 2500 3000 3500 4000

siDia

siSys

S1

S2

Sta

te

Time (ms)

State sequence

1000 1500 2000 2500 3000 3500 4000

siDia

siSys

S1

S2

Sta

te

Time (ms)

State sequence

Manual segmented states (qt) Segmentation results (q*

t)

S1 S2 S1 S2 S1 S2 S2S1S2S2S1 S1

Frequency spectrum (M. Akey et. al.)

The CADScore® AlgorithmCADScore Algorithm

Diastole

Identify

acoustic

features

FilterCombine

features

- 99: High risk

- 0: Low risk

CADscore®

Main clinical studies

CE Mark August 2015Registrationstudy

AC003SH

(2013)

N=228

Symptomatic, no CAD diagnosed

One center (DK)

VALIDATE

(2016)

Dan-NICAD

(2014-2016)

Screening

Studies

N=231Symptomatic, sceduled

for CAG

Two centers (GER)

PlannedStress-ECG

N=1,675Symptomatic, no CAD

diagnosed

Two centers (DK)

PlannedDan-NICAD II

N=1,000Symptomatic, undiagnosed

Multiple centers (GER/UK)

N=2,000New Algorithm

Multiple centers (DK/SWE)

Suspected CAD flow through the system

Percutaneous Coronary

Intervention

Medical Management

StenosisAppropriate for

Intervention

No Interventional Target

Explore Noncardiac

Causes

Medical Management

Medical Management

Low pretest likelihood of CAD

Identification of Chest Pain

Stress Test (Treadmill)

Stress-Echo/MPI/Nuclear

Imaging

cCTA

Invasive Coronary Angiography

Low Risk

Indeterminate CAD

Likely severe CAD

Severe fun

ction

al steno

sis

Intermediate or High Risk

Low RiskHigh Risk

Intermediate or High Risk

Physician Key

Primary Care Practitioner

General Card.

Radiologist

Interventional Card.

The CADScor® system for diagnosing CAD risk using acoustic properties

• The CADScor ® System consists of a disposable patch and reusable sensor/touch-screen interface

• The product is based on the concept that atherosclerosis in coronary vessels will produce unique murmurs detectable by advanced acoustic equipment during diastole

• Minimal training requirements• Measurement takes around 5-8 min. • Noninvasive • No patient exposure to radiation or

contrast dye• High negative predictive value • Relatively low capital and consumable

costs

Characteristics of tests commonly used to diagnose thepresence of coronary artery disease

Sensitivity Specificity NPV

Stress ECG 45-50 85-90 93%

Stress Echo 80-85 80-88 97%

Stress SPECT 73-92 63-87 95%

Dobutamin Stress Echo 79-83 82-86 97%

Dobutamin Stress MRI 79-88 81-91 97%

Vasodilatator Stress Echo 72-79 92-95 96%

Vasodilatator Stress SPECT 90-91 75-84 98%

Coronary CT 95-99 64-83 99%

CADScore* 81-90 45-53 97%

ESC SCAD guidelines 2013

*not in guideline

99 % Socialized medicine so few private clinics

General practitioners refer to outpatient clinics for workup

Workup means: Cardiologist – Echo - ECG bloodtest and history.

Activity:

• Invasive angiography 7,000 per year- 1.4 per 1,000 (Germany: 8.6)

• Cardiac CT 5,000 per year.

• Perfusion test ( Rb-PET) 3,000 per year

Excercise test not used

Stress Echo not used

Health care set up in Denmark

06.11.2017 12

Flow of study AC003SH

Patients referred toCCTA or ICAFor CAD diagnostics

Excl.: Pregnancy, diastolic murmur,heart surgery, arrhythmias, etc.

13

54%18%

28%

Result of diagnostics

Non CAD

Non obstructive CAD

Obstructive CAD

0

10

20

30

40

50

60

70

≤20 >20-30< ≥30

0

5

10

15

20

25

30

35

40

≤20 >20-30< ≥30

No CAD CAD

Results of AC008SH

Pre-test probability of CADDiamond-Forrester updated

2014 KBVGuidelines

15%> Intermediate risk <85% >85%<15%Nofurthertesting

CAGCTA15%< X-ECG<30%

>50% SPECT, C-

MRT, D-MRT, X-Echo

06.11.2017 15

255 personsenrolled

CAG

MPI

N-Contr.CT

High risk 41

Interm. risk

Low. risk

Very low risk

68

90

29

5 11

No-CAD

35

MPI

9

3

Cor. CTRelapse

3

MPI

1

CAG

2

71

Patient flow by DF assessment

Cor. CT

CAD

184

• Danish hospital tariff2016 - Cardiology

– Non contrast CTDKK 906

– Contrast CTDKK 2,621

– MPI DKK 3,015

– CAG DKK 5,997

– (CADSCORE DKK 350)

• Risk changes after combination of scores

06.11.2017 16

Price tag and change of probabilities

06.11.2017 17

255 personsenrolled

CAG

MPI

N-Contr.CT

High risk 61

Interm. risk

Low. risk

Very low risk

48

49

70

2 6

No-CAD

25

MPI

5

2

Cor. CTRelapse

7

MPI

2

CAG

6

71

184

Patient flow by new assessment

Cor. CT

CAD

06.11.2017 18

0

20

40

60

80

100

120

Non-contrast CT Contrast CT MPI CAG

Frequencies in the model

DF Combination

Changes in examination

-37.9% -43.1% -29.0% +4.9%

• Overall costs for diagnostics was DKK 6,096 applying acoustic testing and DKK 6,379 without; saving DKK 274 per patient.

06.11.2017 19

Results

• 28% CAD is not the typically expected population

• Free combination of DF and Score is not anymore in the focus of development

• Newly published study has 8-times more patients

• But the main consideration remains: How to improvethe pre-test probabilities to avoid futile diagnostic

06.11.2017 20

Drawbacks of the model