Cardiovascular MRI: The Future is Now - Washington Hospital Center

Assessment of Viability with CMR: What
is the Value After the STICH Trial?
Christopher M. Kramer MD
Ruth C. Heede Professor of Cardiology
Professor of Radiology
Director, Cardiovascular Imaging Center
University of Virginia Health System

Noninvasive assessment of viability
1. Quantitative SPECT
• > 50 % uptake of tracer ( 201 Tl, sestamibi, tetrofosmin)
2. PET imaging
• mismatch between flow and metabolism (FDG)
3. FDG SPECT
4. Low dose dobutamine echocardiography
• inotropic reserve
5. Contrast echocardiography
• integrity of microcirculation
6. CMR
• inotropic reserve; late gadolinium enhancement

Viability testing and outcomes
Annual Cardiac Death Rate (%)
20
16
12
8
4
0
3.2
-80%
p

Viability imaging – does it matter?
430 patients
Randomized to PET
guided arm vs. standard
care
Death, MI, or cardiac
hospitalization
Benefits in those who
adhered to PET
recommendations
Beanlands R et al, J Am Coll Cardiol 2007;50:2002-12

STICH Trial
Velasquez EJ et al, NEJM 2011;364:1607-16

STICH Trial
Bonow RO et al, NEJM 2011;364:1617-25

Limitations of STICH
Crossover in 17% medical arm, 9 % in CABG arm
Small proportion randomized
2 patients per site randomized per year on average
Viability substudy pts. not randomized
Viability testing optional – only ½ of pts. from main trial
Differences in baseline characteristics
Limited tests for viability – DSE, SPECT
Binary classification of viability
Revascularization not guided by presence of viability
Small n with nonviability
P Chareonthaitawee et al, JACC Img 2012;5:550-8

Viability by CMR
Late gadolinium enhancement
Dobutamine – contractile reserve
Techniques
Applications – acute MI, chronic ischemia
Prognosis

Infarct detection/transmurality
Technique - inversion recovery, nulling of
normal myocardial signal
Infuse 0.15 mM/kg of Gd-DTPA
Image 10-20 minutes later –
Gd becomes trapped
in necrotic scar,
delayed washout
Simonetti et al Radiology 2001;218:215

Viability - Delayed hyperenhancement
Kim, RJ et al Circulation 1999;100:1992-2002

Size of HE
Choi et al Circulation 2001;104:1101-1107

Transmural extent of HE
Transmural extent of hyperenhancement
(%)= area A x 100 / (area A + area B)
Kim, et al. N Engl J Med 2000;343: 1445-53

Reproducibility
48 pts., 3 centers
Imaged x 2, 0.15mM/kg Gd
Wagner A et al. J Am Coll Cardiol
2006;47:2027-33

Improved sensitivity vs. SPECT
6 pts. (13%) with
subendocardial
infarction had no
evidence of
infarction by SPECT
85/181 segments with
subendocardial
infarction had
negative SPECT
Wagner A, et al. Lancet 2003;9355:374

SPECT vs. CMR
78 pts. acute MI at day 7
Ibrahim T et al, J Am Coll Cardiol, 2007;49:208-16

Detecting unrecognized infarcts
ICELAND MI study
936 pts., 67-93 yrs.
91 recognized MI
157 unrecognized MI
6.4 yrs. f/u
Adjusted HR 1.45
Absolute risk↑ 8%
Schelbert E et al, JAMA, 2012;308:890-896

LGE and prognosis
Kwong, RY et al.
Circulation 2006;
113:2733-2743

Acute MI - Contrast patterns
Hyperenhancement Hyperenhancement +
Microvascular obstruction

Regional function
%S
30
25
20
15
10
5
0
*p

Persistent hypoenhancement - no-reflow
Event-free survival (CV death,
reinfarction, CHF, or stroke) for
patients with and without MRI no
reflow
Wu, KC. Circulation 1998;97:765-772.

Time to reperfusion
Tarantini G et al, J Am Coll Cardiol 2005;46:1229-1235

Infarct involution
Ingkanisorn WP et al, J Am Coll Cardiol, 2004;43:2253
Choi CJ et al, J Cardiovasc Magn Reson, 2004;6:915-23

AMI – T2-W edema imaging – area at risk
Abdel-Aty H et al.
JMRI 2007;26:452-9
Friedrich M et al.
J Am Coll Cardiol
2008;51:581-7

T2-W – edema/area at risk
Day 0 Day 1

T2-W – edema/area at risk

T2-W/prognosis
Eitel I et al
JACC
2010;
55:2470-9

Hibernation - Late gadolinium enhancement
50 pts. imaged before revascularization
804/2093 segments dysfunctional at baseline
694/2093 had areas of hyperenhancement
Kim R et al. N Engl J Med. 2000;343:1445

Viability – Late gadolinium enhancement
Kim R et al. N Engl J Med. 2000;343:1445

LGE vs. PET
31 pts., ischemic LV dysf., EF 28±9%
PET and delayed enhancement MRI
11% PET viability showed some HE
C Klein Circulation 2002;105:162

LGE vs. PET
26 pts. w/ LV dysf.
EF 31 11%
FDG-PET, SPECT,
and CMR
17-segment model
HP Kuhl et al. J Am Coll Cardiol 2002;105:162

Viability – Late gadolinium enhancement
Kim et al, N Engl J Med
2000;343:1445

Viability - dobutamine cine MRI
Functional recovery as gold standard (SWT >2mm)
Sens. 89%, Spec. 94%, better than EDWT
↑EF with contractile reserve (14±9% vs. 3±9%, )
Baer et al, JACC
1998:31:1040

Viability - dobutamine tagged MRI
17 patients (12 male)
Age 63 9
Ischemic LV dysfunction
MRI before and 5 2
months after revasc.
Baseline 5 µg/kg/min Dob
10 µg/kg/min Dob
Follow up
Samady et al, Circulation, 2004;110:2410-6

Results
All 180 Segments
Rest %S
Postrevascularization
40
30
20
10
0
-10
-20
y = 0.61x +5.4
r = 0.55, P < 0.001
-10
0
Peak dobutamine %S
Pre-revascularization
10
20
Samady et al, Circulation, 2004;110:2410-6
30
40

Example images – nonviable segment
30% HE
Baseline Dobutamine
Follow-up
nonviable
C Bove et al, Radiology
2006; 240:835-41

Subendocardial MI – 1-50% HE
C Bove et al, Radiology
2006; 240:835-41
* p

Contrast vs. dobutamine
All
segments
1-75%
TEH
No scar or
transmural
scar
25% or 50%
cutoff
Wellnofer et al, Circulation
2004;109:2172-2174

Meta-analysis
J Romero et al, JACC CV
Imaging 2012;5:509-12

Conclusions
If viability is of interest in clinical decision
making, CMR is an excellent technique to use
Late gadolinium enhancement is a well-validated,
accurate method of infarct sizing
Prognostic information of LGE continues to grow
Late gadolinium enhancement and low dose
dobutamine contractile reserve are
complementary in the assessment of likelihood
of contractile recovery