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New Approaches toMonitoring Heart Failure

Before Symptoms Appear

William T. Abraham, MD, FACP, FACCProfessor of Medicine

Chief, Division of Cardiovascular MedicineAssociate Director, Davis Heart & Lung Research Institute

The Ohio State UniversityColumbus, Ohio

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Asymptomaticfluid

retention

Change in impedance or pressure

Worsening heart failure

Can Implantable Monitors Predict Worsening Heart Failure?

Can this prevent hospitalization for worsening heart failure?

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Intrathoracic Impedanceas a Measure of

Heart Failure Clinical Status

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Impedance

“Wetter” Lungs

Impedance Decreases With Increasing Lung Wetness

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Impedance Prior to CHF AdmissionM

ore

F

luid

Less

-28 -21 -14 -7 0

60

70

80

90

Imp

edan

ce (

)

Days Before Hospitalization

Impedance Reduction

Duration of Impedance Reduction

Reference Baseline

CHF, congestive heart failure.

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Evidence Supporting the Useof Intrathoracic Impedance

Animal studies

Completed MID-HeFT study: Medtronic Impedance Diagnostics in Heart Failure Trial

Ongoing FAST study: Fluid Accumulation Status Trial

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MID-HeFT Study

MIDHeFT study– 33 patients, 628 months of follow-up (as of 9/1/03)

– 25 hospitalizations for fluid overload from 10 patients

– Demonstrated an inverse correlation between impedance and both PCWP and net fluid I/O in patients hospitalized for fluid overload

– Demonstrated consistent decreases in impedance in the days preceding hospitalization (ie, predicted hospitalization!)

PCWP, pulmonary capillary wedge pressure; I/O, in/out.Yu C-M, et al. Circulation. 2005;112:841-848.

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MID-HeFT Study Results

Intrathoracic impedance decline preceded the onset of symptoms by mean lead time of 10.3 days (P<0.0001)

Retrospective analysis of the clinical data showed that intrathoracic impedances gradually decreased over approximately 2 weeks prior to HF hospitalization (14 days, P<0.0001) with a total reduction of 11.3%

Using a single detection threshold for all patients, the OptiVol algorithm would have detected 76% of admissions for fluid overload, with an average of only one false warning for every 322 days of patient monitoring

HF, heart failureYu C-M, et al. Circulation. 2005;112:841-848.

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0 1 2 3 4

Days In Hospital

10

20

30

PCWP (mm Hg)

-6

-4

-2

0

Fluid I/O (liters)

55

60

65

70

Impedance ()

Example: Fluid Status During Diuresis

10

50

60

70

80

90Im

ped

ance

(

)

Reference Baseline One Day Prior to Admission

-12.3 +/- 5.3% (P<0.001)

18.3 +/- 10.1 Days

Impedance Leading Up To Admission (n=24)

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Day

s P

rio

r to

Ad

mis

sio

n

Symptom Onset Impedance Decline0

10

20

30

40

Impedance Decline Precedes Symptoms (n=20)

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Automated Detection of Decreases in Intrathoracic Impedance That Precede Hospitalization for CHF

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OptiVol Feature

Physician- programmed threshold

Reference impedance slowly adapts to daily impedance

Daily impedance is the average of one day’s measurements

Accumulation of the difference between the daily and reference impedance

Jun 98 Aug 98 Oct 980

40

80

120

160

200

60

70

80

90

100

>120

110

Jun 98 Aug 98 Oct 98

Thoracic Impedance (ohms)

Daily

Reference

OptiVolFluid Index

OptiVol Threshold

Fluid

P P

P, program.

14

40 80 120 160 2000

20

60

100

Days

Flu

id In

dex

(

day

s)

0 40 80 120 160 200

70

80

90

Days

Imp

edan

ce (

)

0

0

Overview of Detection Algorithm

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FAST Study

FAST study

– 44 patients enrolled/downloaded

– 47 months of total follow-up

– 32 patients to 1 month

– 7 patients with an HF event; 25 were event-free

• 3 clinically relevant HF hospitalizations (in 2 patients)*

• 11 clinically relevant HF medication changes (in 5 patients)*

• 4 adverse events from HF medication changes (in 4 patients)*

– Study corroborated impedance performance from the MID-HeFT study in both event-free and HF event occurrences

*Patients with events are not mutually exclusive.

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FAST Case Study 2 – HF Event

H, hospitalization; O, outpatient visit; M, medication change; F, protocol scheduled follow-up.

Threshold crossed 19 days prior to hospitalization.

Discharged after 1.5 lbsof diuresis

Discharged after 10.8 lbsof diuresis

Days

Impe

danc

e

Patient 110270001

0 10 20 30 40 50 60 70 80 90 100

3040506070

HHH HHHH

F F

MM MMMM

Days

Cum

ulat

ive

Diff

0 10 20 30 40 50 60 70 80 90 100

0306090

120HHH HHHH

F F

MM MMMM

Days

Wei

ght (

lbs)

0 10 20 30 40 50 60 70 80 90 100260

270

280

290

300

F F

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Nov. 5: Lead replacement. Impedance stabilizes several days after procedure.

Oct. 28: Hospitalization for decompensation: orthopnea, peripheral edema, and crackles in lower lungs.

Sept. 29: Crossed OptiVol fluid threshold.

Oct. 7: LV lead dislodgement observed. Decided to reposition lead in November.

Sep 04 Nov 040

40

80

120

160

>200

40

50

60

70

80

>100

90

Sep 04 Nov 04

Thoracic Impedance (ohms)

Daily

Reference

OptiVolFluid Index

OptiVol Threshold

Fluid

InSync Sentry™ Case: Loss of CRT

CRT, cardiac resynchronization therapy.

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Aug 04 Oct 040

40

80

120

160

>200

40

50

60

70

80

>100

90

Aug 04 Oct 04

Thoracic Impedance (ohms)

Daily

Reference

OptiVolFluid Index

OptiVol Threshold

Fluid

Dec 04

Dec 04

InSync Sentry Case:Precipitous Drop in Impedance

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Aug 04 Oct 0440

60

70

80

90

>100

0

150

>200

48

2420

Thoracic Impedance (ohms)

Daily

Reference

Dec 04

50

1612

100

<50

AT/AFTotal hours/day

V. rate during AT/AF (bpm)

Max/day Avg/day

AT, atrial tachycardia; AF, atrial fibrillation; V. rate, ventricular rate.

InSync Sentry Case:Precipitous Drop in Impedance

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Implantable Hemodynamic Monitoring Systems

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Implantable Hemodynamic Monitor

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IHM Home Monitor Clinician Access

Secure Network

RV systolic pressure

RV diastolic pressure

Estimated PA diastolic pressure

Other parameters

IHM System and Information Flow

IHM, implantable hemodynamic monitor; RV, right ventricular; PA, pulmonary artery.

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IHM-Guided Care Reduces Worsening HF in NYHA Class III Patients

Cumulative Events

0

20

40

60

80

100

120

Eve

nts

TCA(n=112)

BCA(n=122)

Patients With Events (#)

33 48

Total HF-Related Events 49 89

Hospitalizations 41 76

Emergency Department Visits 6 11

Urgent Clinic Visits 2 2

Event Rate/ 6 Months

0. 53 0.90

Reduction in Event Rate (%)

41% (P=0.03)

TCA

BCA

642

Months

NYHA, New York Heart Association; BCA, blocked clinician access; TCA, total clinician access.Bourge RC, et al. ACC 2005.

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IHM Case Study

59-year-old white female with ICM– S/P AWMI 2001; CABG 4 SVG 2001

Participant in COMPASS-HF Trial (BCA)

Called 5 days after Valentine’s Day 2005 due to bloating and increased shortness of breath

Weight “stable”

Asked to transmit data

ICM, ischemic cardiomyopathy; AWMI, anterior wall myocardial infarction; CABG, coronary artery bypass graft; SVG, saphenous vein graft; BCA, blocked clinician access.

RV Diastolic Pressure (mm Hg)

RV Systolic Pressure (mm Hg)

ePAD (mm Hg)

ePAD, estimated pulmonary artery diastolic pressure.

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IHM Case Study

Had celebrated Valentine’s Day by going out to eat – At an Indian restaurant!

– Very thirsty – increased fluids

Diuretics increased

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Summary

Long-term trends in intrathoracic impedance may provide an early warning of impending episodes of decompensation in outpatients

Implantable hemodynamic monitoring (IHM) enables the day-to-day management of ventricular filling pressures in CHF patients

Intrathoracic impedance and IHM represent complimentary and promising new technologies for the management of HF