Post on 22-Jul-2020
Dissection Identification and Classification using IVUS:
The iDissection Grading System
Nicolas W Shammas, MD, MS, FACCFounder and Research Director,
Midwest Cardiovascular Research FoundationDavenport, IA
Disclosure
Speaker name: Nicolas W Shammas, MD, MS
.................................................................................
I have the following potential conflicts of interest to report:
Consulting: Intact Vascular, Bard, Boston Scientific
Research and Educational Grants: Intact Vascular, Bard,
Boston Scientific, Phillips
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Imaging Predictors of Restenosis
• Media and external elastic lamina injury
• Circumference of injury
• Small vessel diameter
• Longer lesion length
• Presence and severity of calcium
• Lesion severity underappreciated outside the treated segment
• High residual narrowing underappreciated in treated segment
• Intra-medial route of wire passage in CTO
• Stent under-expansion and asymmetry of expansion
Dissection
Dissection
• Dissection and, to a much lesser extent, plaque compression is what creates the lumen post-PTA
• “intentional dissection” optimizes lumen during vessel prep for subsequent planned therapy
Dissection leaves an unpredictable and unreliable surface
Angiography Has Limitations
• Severity of calcium1,2
• Presence of intraluminal thrombus3
• Plaque morphology4
• Vessel diameter5
• Residual narrowing post-intervention6,7
• Number and severity of dissections including medial and adventitial injury5
1Mintz, Circulation 19952Kashyap, J Endovasc Ther 2008
3Shammas, J Endovasc Ther 20084Arthurs J Vasc Surg 2010
5Korogi, Cardiovasc Interv Radiol 19966Katzen, Circulation 1991
7Cavaye, Interv Angiol 1993
Identifying:
NHLBI Dissection Classification
AMinor radiolucent
areas
BLinear dissection
CContrast outside the
lumen
DSpiral dissection
EPersistent filling
defects
FTotal occlusion w/o
distal antegrade flow
Images adjudicated by core laboratory
NHLBI Dissection ClassificationLimitations:• Formulated in 1985 when current imaging and
therapy techniques were not available
• Considers only the single worst dissection, regardless of how many are present
• Length, depth, extent of dissection not considered
• No consensus on “severe” dissection in the periphery
– Variance in DCB and RCTs and registries
What Is Needed
• Imaging-based dissection classification that is:
– Easily reproducible
– Quickly performed during the procedure
• And captures:
– Presence of injury
– Depth of injury
– Extent of injury
The iDissection Grading System
Shammas, J Invasive Cardiol 2018
• Depth of dissection:
– A: Intima
– B: Media
– C: Adventitia
The iDissection Grading System
Shammas, J Invasive Cardiol 2018
• Extent (circumference) of dissection:– 1: arc of injury < 180°
– 2: arc of injury ≥ 180°
Six iDissection Grades
Shammas, J Invasive Cardiol 2018
A1 B1 C1
A2 B2 C2
Prospective, single arm, single center/operator
Population 15 patients with de novo or stenotic (non-stented) lesions in the femoropopliteal arteries
Treatment Atherectomy + adjunctive PTA• Atherectomy: JetStream XC or B-laser• PTA: POBA, DCB or lithoplasty
Imaging Angiography and IVUS (Eagle Eye ST, Philips) at:• Baseline• Post-atherectomy• Post-PTA
Core Lab Angiography (using NHLBI)• MCRF QVL
IVUS (using iDissection)• MCRF QVL• St. John Providence
iDissection Study Design
Patient and Lesion Characteristics
Shammas, J Invasive Cardiol 2018
Subjects N=15
Age (y) 70.6 ± 8.0
BMI (kg/m2) 30.4 ± 7.5
Gender (male) 93.3 %
Hx of CAD 80 %
Chronic renal insufficiency 6.7 %
Hypertension 100 %
Hyperlipidemia 93.3 %
Smoking 60 %
Current ulcer 26.7 %
Prior target vessel treatment 73.3 %
Rutherford ≥ 3 73.3 %
Lesion Baseline
Lesion length (mm)
108.5 ± 43.1
Treated length (mm)
162.1 ± 100.8
Lesion diameter (mm)
5.7 ± 1.1
% diameter stenosis
71.4 ± 23.4
PACCS grade0134
13.3 %26. 7 %
20 %40 %
Procedural Methods
Shammas, J Invasive Cardiol 2018
Atherectomy
JetStream XC (Boston Scientific) 86.7 %
Blade down mode x 2 100 %
Blade up mode x 2 100 %
B-Laser (Eximo Medical) 13.3 %
Lasing time (sec) 90 ± 50.9
Energy used (J/kg) 50 ± 0
Angioplasty
Shockwave (Shockwave Medical) 33.3 %
Drug coated balloon 100 %
Balloon diameter (mm) 6.1 ± 0.7
Balloon pressure (atm) 10.3 ± 3.1
Balloon inflation time (sec) 310.0 ± 127.9
Procedural Results
Shammas, J Invasive Cardiol 2018
Finding
Procedure Success (n = 14)* 100 %
Device Success (n = 14)** 86.7%
Procedural Complications 0 %
stenting 53. 3 %
Baseline Post-Atherectomy Final: Post-PTA
% diameter stenosis 71.4 ± 23.4 38.1 ± 13.2 19.7 ± 8.8
* < 30% residual narrowing at end of procedure
** < 50% residual narrowing post atherectomy only
Dissection Analysis
The number and severity of dissections seen were compared between angiography and IVUS
– All images adjudicated by core laboratory
– No lesion to lesion comparison available
Finding
Post-atherectomy intramural hematoma 13.3 %
Post-PTA intramural hematoma 13.3 %
Dissections < 6mm 35.3 %
Dissections cumulative < 36mm 97.6 %
Shammas, J Invasive Cardiol 2018
Number of Dissections
Post-Atherectomy
IVUS Angiography
46 8
Post-Adjunctive PTA
IVUS Angiography
39 11
Ratio: 5.75/1 Ratio: 3.55/1
4 to 6 times more dissections are identified with IVUS over
angiography post-intervention
Shammas, J Invasive Cardiol 2018
Severity of Dissections
Post-Atherectomy
IVUS Angiography
A1 – C1 A2 – C2 A – C D – F
40 6 (13%) 7 1 (12%)
Post-Adjunctive PTA
IVUS Angiography
A1 – C1 A2 – C2 A – C D – F
27 12 (31%) 10 1 (12%)
Wider dissections are frequently present post-atherectomy. The total number of dissections appear less after adjunctive PTA, wider
dissections are more frequent at least numerically
Shammas, J Invasive Cardiol 2018
Case StudyNHLBI Dissections
• None
IVUS Dissections
• 5
iDissection Grade
• A1: 2
• B1: 1
• C1: 2
No dissections
1 dissection involved the media
2 involved the intima
2 involved the Adventitia
Shammas, J Invasive Cardiol 2018
A1
Case StudyPost-atherectomy IVUS
A1 C1 C1 B1
Post-angioplasty IVUS
A1 A1 B2 A1 A1Shammas, J Invasive Cardiol 2018
Summary
• Number of dissections:– 46/8 ~6:1
• Depth of dissections:– 39.1% of dissections involved the media
and/or adventitia
• Circumference of dissections:– <180°
• A1: 56.5%• B1: 21.7%• C1: 8.7%
– ≥180°• A2: 4.3%• B2: 6.5%• C2: 2.2%
Shammas, J Invasive Cardiol 2018
Dissections on IVUS vs. Angiography
Conclusions
• Dissections are more statistically significant on IVUS:– Number– Depth– Circumference
• Longer lesions correlated with more dissections• Lack of correlation with dissections on IVUS:
– Balloon pressure/inflation time– Limb ischemia– Calcium burden– Adjunctive lithoplasty
• No apparent predictive variable for dissections ≥180°
Shammas, J Invasive Cardiol 2018
Dissection Identification and Classification using IVUS:
The iDissection Grading SystemNicolas W Shammas, MD, MS, FACC, FSCAI, FSVM
Adjunct Clinical Associate Professor of Medicine, University of IowaFounder and Research Director,
Midwest Cardiovascular Research FoundationDavenport, IA