Transcript Pacemaker and Implantable Cardioverter Defibrillator

The MagnaSafe Registry:
Pacemaker and Implantable
Cardioverter Defibrillator
Safety for Patients
Undergoing Magnetic
Resonance Imaging
Jennifer Cohen, MD, Heather Costa,
PhD, Robert Russo, MD, PhD,
Division of Cardiovascular Diseases,
Scripps Clinic, La Jolla, CA
Presenter Disclosure
Information
• None of the authors have any
disclosures.
Background
• The number of patients with permanent
pacemakers or implantable cardioverterdefibrillators (ICD) in the U.S. is increasing
dramatically.
• Between 1990 and
AICD
200,000
150,000
100,000
50,000
0
04
20
03
20
02
20
01
20
00
20
99
19
98
19
*Zhan, et al, 2008 J Gen Int Med 23 Supp 1:13
Pacemaker
250,000
97
19
2005, an estimated
2.8 million
pacemakers and
690,000 ICDs were
implanted*.
300,000
National estimates of cardiac device implantation
Background
• MRI is the diagnostic modality of choice without
acceptable alternative for many disease states.
• At Scripps Green Hospital:
performed per year.
8,000 MRI’s
• In the Scripps Health System:
performed in 2007.
18,000 MRI’s
• There is a 50-75% estimated probability that a
patient with a PM or ICD will need an MRI.
MRI Safety Studies
• Small number of published studies at 1.5T with
a total of approximately 350 patients.
• Varying effects including impedance changes,
battery depletion and an increase in pacing
thresholds.
• No serious adverse events have been reported.
• No comparison to a control group.
The MagnaSafe Registry
A retrospective, single site experience
• Data used to design the prospective, multicenter MagnaSafe Registry.
• Establish expected event rates.
• Sample size calculations.
• Design the interrogation protocol.
The MagnaSafe Registry
•
Prospective, multi-center registry to begin enrollment in
April 2009.
•
Expected enrollment:
•1000 patients with permanent pacemakers
•500 patients with ICDs
•
Clinically-indicated, non-research, non-thoracic MRI
deemed medically necessary by the ordering physician.
•
Performed under a conditional IDE with the guidance of
the FDA .
The MagnaSafe Registry
•
Prospectively document the incidence of adverse events
or changes in device parameters associated with
undergoing an MRI.
•
Will provide physicians the risk-assessment data needed
to discuss the use of MRI with their patients as a
diagnostic tool when no alternative test is available.
•
Ultimately, the goal is to amend the guidelines for
performing MRI in patients with implanted cardiac
devices.
Hypothesis
• Magnetic resonance imaging at 1.5T
can be performed safely in selected
patients with permanent
pacemakers and implantable
cardioverter-defibrillators using an
optimized device programming
protocol and screening process.
Methods
•
Patients presented for a MRI that was deemed
medically necessary by the ordering physician without
acceptable alternative examination.
•
Clinical informed consent was obtained by a
cardiologist who was present during the scan.
• No scans were excluded.
• No SAR limits placed.
• Technicians were permitted to deviate from normal
operating mode.
•
Performance of a diagnostic exam was a priority.
Methods
• Device interrogation was performed before and
immediately following the scan.
• Non-invasive monitoring performed.
• IRB approval was obtained for retrospective
analysis of data previously obtained during
clinically-indicated (non-research) MRI.
Methods
Device Interrogation
•
Pacemaker-dependent patients were reprogrammed
to asynchronous mode (VOO or DOO). Magnet
response was disabled.
•
Non-dependent patients were programmed to no
pacing.
• For ICDs, tachycardia-therapy was turned off.
• Pre and post-MRI interrogations were identical:
•Measurement of intrinsic P/R waves, all lead
impedances, shock lead impedances, all lead
thresholds measured at a fixed pulse width.
Methods
Control Group
•
A control group was studied to determine the
variability of device parameters without MRI.
•
34 patients with pacemakers and ICDs
underwent 2 device interrogations 1 hour
apart to determine variation (without MRI).
•
Recruitment for the Control Group is ongoing.
Methods
Primary Outcomes
• Decrease in battery voltage ≥ 0.04 V
• Change in lead impedance:
•Change in pacing lead impedance by ≥ 50 Ω
•Change in shock lead impedance by ≥ 3 Ω
• Change in lead threshold
•Increase in lead threshold ≥ 0.50 V at 0.4 ms
• Change in P/R wave amplitude
•Decrease in P wave amplitude ≥ 50%
•Decrease in R wave amplitude ≥ 25%
• Loss of capture during scan, induced arrhythmia, device
failure requiring generator or lead replacement
Results
Clinical Experience
• 125 generators and 255 leads.
• 157 clinically-indicated 1.5T MRI scans between
Jan 2006 and March 2009.
• Length of MRI scan 48.9±20.67 minutes.
• One patient had a pacemaker and an ICD in
place.
Results
Baseline Characteristics
Control
MRI Patients
Gender
68% Male
76% Male
Age
77 +/- 10 years
76 +/- 12 years
Number of generators
34
125
Number of leads
68
177
Average time between
implant and interrogation
2.3 +/- 2.4 years
(range 1- 3251 days)
2.6 +/- 2.1 years
(range 4-3886 days)
Atrial leads
28
113
RV/LV leads
34/6
124/18
Pacer Dependent
12%
22%
Pacemakers/ICDs
41%/59%
67%/33%
Results
Types of Devices
Dual chamber
pacemaker
13%
3%
17%
4%
Single chamber
pacemaker
2%
61%
Dual chamber ICD
Single chamber
ICD
Bi-ventricular ICD
Bi-ventricular
pacemaker
Results
Predicted Breakdown of Scans for
MagnaSafe
Scans from Retrospective Data
3%
2%
3%
Brain
7%
Spine
4%
31%
8%
42%
Joint
Cardiac
Abdomen/Pelvis
Orbit
Neck
Other
8%
3% 4%
8%
Brain MRI/MRA
37%
40%
Spine
Joint
Abdomen/Pelvis
Orbit
Other MRI
Results
• No arrhythmias: atrial or ventricular
• No loss of capture
• No electrical reset-to-on
• No generator or lead replacements
• No syncope
• No deaths
• All scans were performed except for one due
to severe claustrophobia
Results
Device Parameter Changes
Control (%) MRI Patients (%)
Battery Voltage Decrease
> 0.04 V
p
0 (0/34)
4.2(4/96)
0.57
All Pacing Lead Impedance
Change > 50 ohms
3.2 (2/63)
5.8 (12/207)
0.53
Shock Lead Impedance Change
> 3 ohms
15.8 (3/19)
30.4 (7/23)
0.31
P Wave Decrease > 50%
0 (0/23)
1.5 (1/65)
1.0
R Wave Decrease > 25%
3.3 (1/30)
2.7 (2/75)
0.48
Results
Device Parameter Changes
Atrial Lead Threshold
Increase > 0.5 mV
RV Lead Threshold Increase
> 0.5 mV
LV Lead Threshold Increase
> 0.5 mV
All Leads Threshold Increase
> 0.5 mV
Control (%)
MRI (%)
0.0 (0/23)
1.2 (1/87)
0.0 (0/33)
4.1 (4/97)
16.7 (1/6)
14.3 (2/14)
1.6 (1/62)
3.5 (7/198)
Results
Dependency
%
20
18
16
14
12
10
8
6
4
2
0
MRI Patients
4.7%
p=1.0
3.0%
3.6%
p=0.43
5.2%
3.4%
0%
All Patients
Dependent
Not
Dependent
Controls
Results
ICD versus Pacemaker
20
18
16
14
12
%
MRI Patients
10
8
6
4
p=0.3
4.7%
4.5%
5.0%
3.0%
p=1.0
2.6%
3.9%
2
0
All Patients
ICD
Pacemaker
Controls
Results
Brain Scans
20
18
16
14
12
%
10
8
6
p=1.0
4.7%
4.7%
4.7%
All MRI Scans
Brain Only Scans
Other Scans
4
2
0
Results
Length of Scans
20
18
16
14
%
12
10
6.1%
8
6
4
3.0%
4.7%
3.8%
5.0%
4.7%
>90 min
All MRI
Patients
2
0
0 min
(Controls)
1-30 min
31-60 min 61-90 min
Results
Multiple Scans
20
18
16
14
12
%
10
8
6
p=0.33
4.7%
5.4%
3.2%
4
2
0
All MRI Patients
Multiple Scans
Single Scan
Results
Time Since Implant
%
20
18
16
14
12
10
8
6
4
2
0
MRI Patients
Controls
4.7%
5.4%
4.8%
3.0%
3.1%
1.1%
0%
0%
All
0-30 days 31-180
Patients
days
>180
days
Results
Lead Threshold Changes
MRI Patients
160
140
Frequency
120
100
80
60
Leads = 33
Leads = 19
40
20
0
-1
-0.75
-0.5
-0.25
0
0.25
0.5
0.75
Change in V at 0.4 ms
Average Lead Threshold Change 0.02 ± 0.18 V
1
Results
Lead Threshold Changes
Controls
50
45
Frequency
40
35
30
25
20
Leads = 8
15
Leads = 8
10
5
0
-1
-0.75
-0.5
-0.25
0
0.25
0.5
0.75
Change in V at 0.4 ms
Average Lead Threshold Change 0 ± 0.16 V
1
Results
Battery Voltage Changes
MRI Patients
80
Frequency
70
60
50
40
30
Generators = 19
Generators = 6
20
10
0
-0.6
-0.4
-0.2
0
0.2
0.4
Change in Battery Voltage (V)
Average Battery Voltage Change -0.004 ± 0.016 V
0.6
Results
Battery Voltage Changes
Controls
30
Frequency
25
20
15
Generators = 5
10
Generators = 3
5
0
-0.6
-0.4
-0.2
0
0.2
0.4
Change in Battery Voltage (V)
Average Battery Voltage Change 0.00 ± 0.01 V
0.6
Results
Lead Impedance Changes
MRI Patients
120
80
60
Leads = 129
40
Leads = 54
20
5
17
0
15
5
12
0
10
75
50
25
0
5
-2
0
-5
5
-7
00
-1
25
-1
50
-1
75
0
-1
Frequency
100
Change in Lead Impedance (ohms)
Average Lead Impedance Change -5.9 ± 25.1 Ω
Results
Lead Impedance Changes
Controls
30
20
15
Leads = 34
Leads = 19
10
5
5
17
0
15
5
12
0
10
75
50
25
0
5
-2
0
-5
5
-7
00
-1
25
-1
50
-1
75
0
-1
Frequency
25
Change in Lead Impedance (ohms)
Average Lead Impedance Change 6.2 ± 22.5 Ω
Conclusions
• A very low incidence of device parameter
change was noted after MRI at 1.5T.
• No patient experienced device failure or a
permanent change in lead threshold.
• Based on these findings, we anticipate
<5% rate of device failure, <5% rate of
permanent reprogramming, <10% rate of
temporary reprogramming for the
prospective MagnaSafe Registry.
MagnaSafe
Clinical care
Research
Patient with cardiac device
and MRI clinically indicated
Subjects enrolls in study
Device parameters recorded
Magnetic resonance imaging
Clinical Care
Registry
Device parameters recorded
Restore or Adjust settings
Parameter Change?
Yes
No
Follow-up interrogation
within 7 days
Research
MagnaSafe
Follow-up Interrogation at
3 months
Follow-up Interrogation at
6 months
Follow-up interrogation at
3-6 months when clinically
indicated