1 new approaches to monitoring heart failure before symptoms appear william t. abraham, md, facp,...
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1
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?
3
Intrathoracic Impedanceas a Measure of
Heart Failure Clinical Status
4
Impedance
“Wetter” Lungs
Impedance Decreases With Increasing Lung Wetness
5
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.
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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