pitfalls and limitations of qca in the analysis of

Cardiovascular Research FoundationCardiovascular Research FoundationColumbia University Medical CenterColumbia University Medical Center

Pitfalls and Limitations of QCA in the Analysis of Bifurcation Lesions

Pitfalls and Limitations of QCA in the Pitfalls and Limitations of QCA in the Analysis of Bifurcation LesionsAnalysis of Bifurcation Lesions

Alexandra Lansky, MDAssociate Professor, Clinical MedicineColumbia University Medical Center

Alexandra Lansky, MDAssociate Professor, Clinical MedicineColumbia University Medical Center

The realities of bifurcation lesionsare the greatest challenges of QCAThe realities of bifurcation lesionsThe realities of bifurcation lesionsare the greatest challenges of QCAare the greatest challenges of QCA

• Lesion location is variable in bifurcation disease (ostial side branch, within the carina)

• One bifurcation lesion but 3 vessel segments (4 for trifurcations)

• How to quantify extent of lesion length?• Bifurcation stenoses rarely seen in one

single view- require multiple views for analysis

•• Lesion location is variable in bifurcation Lesion location is variable in bifurcation disease (disease (ostialostial side branch, within the side branch, within the carina)carina)

•• One bifurcation lesion but 3 vessel One bifurcation lesion but 3 vessel segments (4 for trifurcations)segments (4 for trifurcations)

•• How to quantify extent of lesion length?How to quantify extent of lesion length?•• Bifurcation Bifurcation stenosesstenoses rarely seen in one rarely seen in one

single viewsingle view-- require multiple views for require multiple views for analysisanalysis

Lesson #1: The BasicsLesson #1: The BasicsBifurcations need work to uncover Bifurcations need work to uncover

pathologypathology

The The ““Step downStep down”” phenomenon is a major phenomenon is a major limitations of Standard QCA when applied to limitations of Standard QCA when applied to

bifurcation analysesbifurcation analyses

Method to Method to determine the determine the proper reference proper reference diameter for each diameter for each individual segmentindividual segment

Lesson#2 Beware and understand the Lesson#2 Beware and understand the limitations of QCA bifurcation results!limitations of QCA bifurcation results!

Left Main Trifurcation with extreme Left Main Trifurcation with extreme proximal:distalproximal:distal vessel missvessel miss--matchmatch

Limitations of Standard AnalysisLimitations of Standard Analysis

Problem:Problem: Mismatch between Mismatch between proxproxvessel and distal vessel vessel and distal vessel

Results in:Results in: Overestimated ReferenceOverestimated ReferenceOverestimated %DSOverestimated %DSBetter for lesion lengthBetter for lesion length

Solutions:Solutions:Use Distal Reference orUse Distal Reference orLimit analysis to distal PVLimit analysis to distal PV

Greatest Limitation: Reference DiameterGreatest Limitation: Reference Diameter

••ProblemsProblems:: Vessel contour track into MLDVessel contour track into MLDCannot assess lesion lengthCannot assess lesion length

••Results inResults in: : Underestimates referenceUnderestimates referenceUnderestimates %DSUnderestimates %DS

••SolutionSolution: : Use Distal ReferenceUse Distal Reference

Gerard Finet: Dept. of Hemodynamics and Interventional CardiologyCardiovascular Hospital Louis Pradel - Lyon - France

Constant RVD relation between PV and SB in the normal coronary tree

N= 47 pts (173 bifurcations)

For all 4.5 ² D m 4 ² D m ² 4.5 3.5 ² D m ² 4 3 ² D m ² 3.5 2.5 ² D m ² 3 Dm ² 2.5

# of bifurcation 173 21 24 18 43 33 35

Dm (mean±DS) 3.339±0.948 5.195±0.561 4.202±0.143 3.726±0.132 3.192±0.146 2.748±0.119 2.224±0.186

Dd-larger (mean±DS) 2.708±0.774 4.159±0.529 3.334±0.3 3.046±0.338 2.559±0.258 2.312±0.273 1.831±0.226

Dd-smaller (mean±DS) 2.236±0.689 3.476±0.548 2.828±0.333 2.476±0.501 2.027±0.337 1.889±0.241 1.583±0.209

Reduction in mm (mean±DS) 0.631±0.365 1.036±0.538 0.868±0.333 0.681±0.321 0.633±0.246 0.436±0.245 0.394±0.154

% reduction 18.9 19.93 20.64 18.26 19.84 15.86 17.72

Mean ratio 0.678 0.6846 0.6865 0.685 0.7019 0.6595 0.656

Variables are presented as mean ± SD D in mm Dm: Diameter of the mother vessel Dd-larger: Diameter of the larger daughter vessel Dd-smaller: Diameter of the smaller daughter vessel Reduction: difference between the diameter of mother vessel and the diameter of the larger daughter vessel Ratio: Dm / (Dd-larger + Dd-smaller)

Dmother = 3.33 ±0.94 mm

Ddaughter minor= 2.23 ±0.68 mm

Ddaughter major= 2.70 ±0.77 mm

∆D = 0.63 ±1.05 mm

Side branch

MurrayMurray’’s s lawlawExperimental Experimental approachapproach

33321 vvp DDD +=)(66.0

21 vvp DDD +⋅=

Dp: parent vessel diameter

Dv1: daughter 1 vessel diameter

Dv2 : daughter 2 vessel diameter

Constent RVD relation between PV and SB in the normal coronary tree

N= 47 pts (173 bifurcations)Finet et Gilard

Three sections model for the Three sections model for the bifurcation analysis (MEDIS)bifurcation analysis (MEDIS)

Proximal sectionProximal section

Distal1 sectionDistal1 section

Distal 2Distal 2sectionsection

Arterial contour: 4 segmentsArterial contour: 4 segments

Distal 2 Fragment Distal 2 Fragment Delimiter Delimiter

Proximal SectionProximal Section

Concept is to exclude the carina from consideration in Concept is to exclude the carina from consideration in the assessment of the reference measures (avoids the assessment of the reference measures (avoids overestimation of reference for the distal vessels)overestimation of reference for the distal vessels)

The problem is that the carina is left The problem is that the carina is left ““in limboin limbo””

Proximal Proximal SectionSection Flagged Flagged

central central fragment fragment

To measure diameters in the central fragment of To measure diameters in the central fragment of a distal section, an artificial contour in the central a distal section, an artificial contour in the central

fragment is generated automaticallyfragment is generated automatically

Distal 1Distal 1SectionSection

Automatically Automatically interpolated interpolated arterial contour arterial contour

Dedicated Bifurcation SoftwareDedicated Bifurcation Software

ButBut……Different Results for Same LesionDifferent Results for Same Lesion

BIFURCATION Types from one Study…BIFURCATION Types from one StudyBIFURCATION Types from one Study……

60% 18%

Novel bifucation software solves some but not all problems

Novel Novel bifucationbifucation software solves some software solves some but not all problemsbut not all problems

• Benefits:Single analysis of the 3 vessels, fast, easy, more reproducible)More accurate reference vessel diameter (outside carina)More accurate %DS (outside carina)

• Limitations:Reference in carina is interpolated for the segment analyzed (LAD vs LCx vs LM)Single lesion in Carina is reported 3 times (with different reference, MLD, %DS depending on vessel analyzed)Cannot always acquire in a single best view

•• Benefits:Benefits:Single analysis of the 3 vessels, fast, easy, more Single analysis of the 3 vessels, fast, easy, more reproducible)reproducible)More accurate reference vessel diameter (outside carina)More accurate reference vessel diameter (outside carina)More accurate %DS (outside carina)More accurate %DS (outside carina)

•• Limitations:Limitations:Reference in carina is interpolated for the segment Reference in carina is interpolated for the segment analyzed (LAD analyzed (LAD vsvs LCxLCx vsvs LM)LM)Single lesion in Carina is reported 3 times (with different Single lesion in Carina is reported 3 times (with different reference, MLD, %DS depending on vessel analyzed)reference, MLD, %DS depending on vessel analyzed)Cannot always acquire in a single best viewCannot always acquire in a single best view

Baseline Final

The challenge is to determine (inter-(extra)-polate) the true diameter of the carina

simulating the undiseased state????

This would result in a constant reference, MLD and %DS in the carina

Analysis in 2 Analysis in 2 segments with segments with interpolation interpolation in the carinain the carina

GE: Bifurcation Quantification Prototype GE: Bifurcation Quantification Prototype

Lesson # 3: QuestionLesson # 3: Question

In assessing the longIn assessing the long--term angiographic outcomes of a term angiographic outcomes of a bifurcation lesion, which is correctbifurcation lesion, which is correct……

1.1. A single measure of LLL for the bifurcation lesion is the A single measure of LLL for the bifurcation lesion is the best measure to compare 2 treatment groups because it best measure to compare 2 treatment groups because it is a surrogate of is a surrogate of intimalintimal hyperplasiahyperplasia

2.2. In a bifurcation lesion, LLL is only meaningful if applied In a bifurcation lesion, LLL is only meaningful if applied to a specific vessel segment that has minimal vessel to a specific vessel segment that has minimal vessel taper taper

3.3. Binary Binary restenosisrestenosis is the only angiographic parameter at is the only angiographic parameter at followfollow--up that can be applied to the entire bifurcation up that can be applied to the entire bifurcation lesion (PV and SB)lesion (PV and SB)

LLL is only meaningful if the segment analyzed is specifiedLLL is only meaningful if the LLL is only meaningful if the

segment analyzed is specifiedsegment analyzed is specified

1 – Proximal Edge of the Prox PV Stent2 – Prox PV Stent3 – Distal PV Stent* 4 – Distal Edge of the PV Stent 5 – SB Stent*

1

23

4

5

67

8

9

10

6 – Distal Edge of the SB Stent* 7 – Carina 8 – Ostium of the SB (5mm)9 – PV In-Lesion10 – SB In-Lesion

PV

PV

SB

*if additional stent(s) placed

Lesson #4: Diagnostic ConsiderationsOstial SB Lesion Severity at BaselineLesson #4: Diagnostic ConsiderationsLesson #4: Diagnostic ConsiderationsOstialOstial SB Lesion Severity at BaselineSB Lesion Severity at Baseline

LAD

Fractional Flow Reserve (FFR <0.75 = ischemia)Fractional Flow Reserve (FFR <0.75 = ischemia)• SB FFR measured in 94 pts after side branch jailing• FFR reflects both degree of stenosis and myocardial territory

Bon-Kwon Koo, MD

Lesson #5: Diagnostic ConsiderationsOstial SB Lesion Severity after SB Jailing

Lesson #5: Diagnostic ConsiderationsLesson #5: Diagnostic ConsiderationsOstialOstial SB Lesion Severity after SB JailingSB Lesion Severity after SB Jailing

Angiography Angiography vsvs FFR: To treat or Not?FFR: To treat or Not?

100908070605040

1.0

.9

.8

.7

.6

.5

Percent Stenosis (%)

Frac

tiona

l Flo

w R

eser

ve

QCA vs. FFRin Jailed side branch lesions (n=94)

Functionally significant stenosis

r = - 0.464p < 0.001

FFR FFR (< 0.75)(< 0.75) vs. QCA vs. QCA (% stenosis) (% stenosis) Bon-Kwon Koo, MD

Sens

itivi

ty

1 - specificityAUC: 0.85 (95% CI: 0.76 - 0.94)

- All Lesions (n=94) -

SpecificitySpecificitySensitivitySensitivity% stenosis% stenosis

0.770.770.80.885%85%

0.390.391.01.075%75%

1.00.75.50.250.00

1.00

.75

.50

.25

0.00

Best CutBest Cut--off Valueoff Value

..

The angiographic %DS cutThe angiographic %DS cut--off value for (jailed) side off value for (jailed) side branches is 75% DSbranches is 75% DS

DS<75%: high NPV DS<75%: high NPV Generalizability to nonGeneralizability to non--jailed SB (inital evaluation)?jailed SB (inital evaluation)?Reason: Reason:

radiographic artifact, limitations of QCAradiographic artifact, limitations of QCAsmall branches, small myocardial mass, low flowsmall branches, small myocardial mass, low flowInitial edema after stentingInitial edema after stenting

More strict angiographic evaluation criteriaMore strict angiographic evaluation criteria and and less aggressive SB less aggressive SB interventionintervention strategystrategy should be appliedshould be applied

Bon-Kwon Koo, MD

Are significant side branch lesions really significant?

After Bifurcation PCI…A preponderance of Restenosis occurs in the SB Ostium

After Bifurcation PCI…A preponderance of Restenosis occurs in the SB Ostium

SB Ostium Restenosis

PreprocedurePreprocedure FinalFinal 6 Months Follow-Up6 Months Follow-Up

LAD

Lesson #6: Diagnostic ConsiderationsSB Ostium Stent Under Expansion

Lesson #6: Diagnostic ConsiderationsLesson #6: Diagnostic ConsiderationsSB SB OstiumOstium StentStent Under ExpansionUnder Expansion

LA : 2.23mm2

SA : 2.23mm2

6M

Lesson #6: Diagnostic ConsiderationsSB Ostium Stent Under Expansion

Lesson #6: Diagnostic ConsiderationsLesson #6: Diagnostic ConsiderationsSB SB OstiumOstium StentStent Under ExpansionUnder Expansion

Crush Technique: IVUS InsightsCrush Technique: IVUS Insights40 pts post bifurcation crush: Minimum stent CSA (MSA) was

assessed at 5 distinct locations: Restenosis 17% (6/35); all 6 in SB ostium and 1extenting to PV

40 pts post bifurcation crush: Minimum stent CSA (MSA) was assessed at 5 distinct locations: Restenosis 17% (6/35); all

6 in SB ostium and 1extenting to PV

Costa et al. J Am Coll Cardiol 2005;46:599-605

Costa et al. J Am Coll Cardiol 2005;46:599-605

Bifurcation Lesions Treated with Crush Stenting with Final IVUS in Both Branches

Bifurcation Lesions Treated with Crush Stenting with Final IVUS in Both Branches

Suggested Improvements in Analysis Algorythms

Suggested Improvements Suggested Improvements in Analysis in Analysis AlgorythmsAlgorythms

Methodology and algorithm for contour detection• Ostial Sidebranch flaring• Interpolation across carina is artificial (should not

be done)• Carina reference should reflect un-diseased

diameter (this would result in a constant reference and %DS)

Reporting should allow one single MLD and DS for the entire bifurcation lesionAllow multiple segment of interest analysis (DES bifurcation software) to avoid having to do multiple segment analyses

Methodology and algorithm for contour detectionMethodology and algorithm for contour detection•• OstialOstial SidebranchSidebranch flaringflaring•• Interpolation across carina is artificial (should not Interpolation across carina is artificial (should not

be done)be done)•• Carina reference should reflect unCarina reference should reflect un--diseased diseased

diameter (this would result in a constant reference diameter (this would result in a constant reference and %DS)and %DS)

Reporting should allow one single MLD and DS for the Reporting should allow one single MLD and DS for the entire bifurcation lesionentire bifurcation lesionAllow multiple segment of interest analysis (DES Allow multiple segment of interest analysis (DES bifurcation software) to avoid having to do multiple bifurcation software) to avoid having to do multiple segment analysessegment analyses

QCA Methods and ReportingQCA Methods and ReportingQCA Methods and Reporting

1 – Proximal Edge 2 – Proximal Stent3 – Distal PV Stent* 4 – Distal Edge of the PV Stent 5 – SB Stent*

1

23

4

5

67

8

9

10

6 – Distal Edge of the SB Stent* 7 – Carina 8 – Ostium of the SB (5mm)9 – PV In-Lesion10 – SB In-Lesion

PV

PV

SB

*if additional stent(s) placed