JONATHON LEIPSIC MD FRCPC FSCCT

A S S I S T A N T P R O F E S S O R O F R A D I O L O G Y A N D

C A R D I O L O G Y V I C E C H A I R M A N O F R A D I O L O G Y

U N I V E R S I T Y O F B R I T I S H C O L U M B I A

MDCT for TAVR: Where We Are

Disclosures

Speaker’s bureau: GE Healthcare and Edwards LifeSciences

Research Grant- GE Healthcare

Advisory Board- GE Healthcare and Edwards LifeSciences

Equity- TC3

Aortic Stenosis

Most common valvular heart disease 2-4% of adults >65 years

In US, >50,000 surgical AVR/year for AS

Hospital mortality 9% in patients >65 years

33% of AS patients >75 years deemed not surgical candidate (Iung B, Eur Heart J, 2005)

Prognosis of symptomatic patients with severe AS is very poor

TAVR has seen rapid adoption as a minimally invasive alternative to conventional surgery

Leon MB, Smith CR, Mack M et al. N Engl J Med 2010;363:1597-607

All Cause Mortality

0 6 12 18 24

Numbers at Risk

TAVI 179 138 122 67 26

Standard Rx 179 121 83 41 12

∆ at 1 yr = 20.0%

NNT = 5.0 pts

Standard Rx

TAVI

All

-cau

se m

ort

ali

ty (

%)

Months

0

20

40

60

80

100

50.7%

30.7%

CRAIG R. SMITH, MD O N B E H A L F O F T H E P A R T N E R T R I A L

I N V E S T I G A T O R S

Transcatheter vs. Surgical Aortic Valve Replacement in High Risk Patients

with Severe Aortic Stenosis: Results From The PARTNER Trial (A)

ACC 2011 | New Orleans | April 3, 2011

0

0.1

0.2

0.3

0.4

0.5

0 6 12 18 24

TAVR

AVR

Months

348 298 260 147 67

351 252 236 139 65

No. at Risk

TAVR

AVR

26.8

24.2

Primary Endpoint: All-Cause Mortality at 1 Year

HR [95% CI] =

0.93 [0.71, 1.22]

P (log rank) = 0.62

0

0.1

0.2

0.3

0.4

0.5

0 6 12 18 24

TAVR

AVR

All-Cause Mortality Transfemoral (N=492)

Months

244 215 188 119 59

248 180 168 109 56

No. at Risk

TAVR

AVR

26.4

22.2

HR [95% CI] =

0.83 [0.60, 1.15]

P (log rank) = 0.25

Outline

Systematic approach to aortic root and annulus assessment for patients undergoing transcatheter

aortic valve implantation (TAVI)

Provide a rational approach to annular sizing with CT

Angle prediction for valve implantation

Iliofemoral artery assessment

Prosthesis Sizing for TAVR

Ultimate Goal: To displace the native aortic valve leaflets and deploy the aortic prosthesis within the

native aortic valve annulus If aortic prosthesis deployment is too high:

Aortic injury Paravalvular aortic regurgitation

Embolization of aortic prosthesis into the aorta

If aortic prosthesis deployment is too low: Mitral valve dysfunction (regurgitation, restricted motion of anterior

leaflet) Heart block

Paravalvular aortic regurgitation

Embolization of aortic prosthesis into the left ventricular cavity

Aortic Annulus

Annulus Sizing The aortic annulus is a complex 3 dimensional structure Previous anatomical studies established that the aortic

annulus is a 3-pronged coronet rather than a circular structure

It has three anchor points at the nadir of each aortic cusp

The attachment of the aortic cusps is semilunar

It extends throughout the aortic root from the left ventricle distally to the sinotubular

junction

Piazza N et al. Anatomy of the Aortic Root. Circ Cardiovascular Interventions. 2008

Elliptical Annulus

The annulus is commonly oval-shaped Reported in approximately 50% of

patients evaluated for TAVR The mean difference between coronal and sagittal measurements was 3.0

1.9 mm Oval geometry of the annulus has been

previously underappreciated on imaging but well described in the

surgical literature

Tops LF, Wood DA, Delgado V, et al. Noninvasive evaluation of the aortic root

with multislice computed tomography: implications for transcatheter aortic valve replacement.

JACC Cardiovasc Imaging 2008; 3:25 -32

Piazza et al. Anatomy of the Aortic Root. Circ Intervention 2008

Accurate measurement of the aortic annulus is

essential for determining aortic prosthesis size

Valves selected based on annular sizing, Aortic annular measurements for TAVI rely upon imaging,

traditionally by:

Transthoracic echocardiography (TTE)

Transesophageal echocardiography (TEE)

Aortic angiography

Discordance between imaging modalities is not uncommon, and the “true” annular size based upon

imaging findings can be controversial

3D aortic annular and root morphology and dimensions

ECG-gated MDCT may serve as an adjunct method for aortic annular measurement

Advantages to use of ECG-gated MDCT:

Non-invasive

Routinely performed for patients prior to TAVI

Allows for true 3D measurement of aortic valve without assumptions

Allows for concomitant assessment of aortic valve, coronary arteries, and aortoiliac system

THERE IS OFTEN DISCORDANCE BETWEEN AORTIC

ANNULAR DIMENSIONS BY MDCT VERSUS ECHO

ECG-gated MDCT observes generally larger annular sizes than either TTE or TEE

Example: Pre-procedural and peri-procedural

annular measurements vary between 17-24 mm

21 mm

24 mm

17 mm

PR

E-P

RO

CE

DU

RA

L E

VA

LU

AT

ION

P

ER

I-PR

OC

ED

UR

AL

EV

AL

UA

TIO

N

Possible reasons for ECG-gated MDCT and

echo discordance for annular sizing

1. Aortic Annular Shape: 2D assessment of the annulus

may not adequately for its elliptical (non-circular) shape

2. Aortic Annular Plane: Aortic leaflet insertions into the

annulus are not necessarily at the same level

Right coronary cusp leaflet often inserts inferior to the left

and non-coronary cusp leaflets

3. Wrong plane: 2D diameter measurement of aortic annulus

may be oblique to the true annular plane

4. Variability: Inter-observer, intra-observer and/or intra-test

variability

5. Test Quality: Suboptimal or technically difficult images

Lessons Learned

Annulus Sizing There have been a number of published methods for measurement of the

aortic annulus on MDCT.

Initial published reports had evaluated the annulus in a coronal and

sagittal fashion

Regardless of the MDCT methods used to determine the aortic annular diameter, the absolute differences between MDCT and TTE or TEE are greater than the

differences between TEE and TTE

If MDCT measures of annular diameter are employed, they may influence or modify the TAVI

strategy in a considerable number of cases: 38% of patients using long and short-axis diameters

David Messika-Zeitoun, Jean-Michel Serfaty, Eric Brochet et al. Multimodal Assessment of the Aortic Annulus Diameter: Implications for Transcatheter Aortic Valve Implantation J. Am. Coll. Cardiol., January 19, 2010; 55: 186 - 194

There are differences between ALL

MDCT Methods and Echo

MDCT “3-chamber” Projection

High correlation in annular measures between

parasternal long-axis view by TTE or 3-chamber view

by TEE and “3-chamber” plane by MDCT

“3-chamber” Projection

“3 chamber projection correlates well but leaves much of the important 3-dimensional data on the

table

Moving away from 3 chamber projections to bi-dimensional measurements of the root and basal

ring incorporating more of the root geometry

Our laboratory’s experience has observed the basal mean diameter to be the most reproducible

measurement (R=0.87)

The basal mean diameter tends to measure ~1.0-1.5 mm larger than TTE parasternal long axis

measurements

Which MDCT method is most

Reproducible?

Under review JACC interventions

Aortic Annular Sizing:

Basal mean diameter

(1) (2)

(3) (4)

The Virtual Basal Ring

Source: Leipsic et al JACC Img April 2011

Sinotubular junction

Aortic leaflets

Aortic Annulus

Aortic Annular Diameter

RC = Right coronary cusp; NC = Non-coronary cusp; LC = Left coronary cusp

Aortic Annular Sizing: Basal Ring Area-Derived Diameter

Calculation for the Area Derived Diameter

Advantages to MDCT methods Greater reproducibility

Less sensitive to minor changes in obliquity’

“3-D”

“2-D”

Integrating CT into Annular Sizing

Sizing currently based on ECHO

Nevertheless, our laboratory’s practice is to integrate 3D ECG-gated MDCT as a complementary

measurement for transcatheter aortic valve sizing At a minimum, ECG-gated MDCT annular measurements

can be employed as a “tiebreaker” if discordance between TTE and TEE

At a maximum, ECG-gated MDCT annular measurements may be considered for valve sizing

We integrate the expected 1-1.5 mm size difference between these two measurements into a new CT

based sizing criteria

What are the current ECHO based

recommendations?

26mm Valve

23mm Valve

Usually tend to oversize by at least 2mm on echocardiography

26mm Valve

23mm Valve 23mm Valve

26mm Valve

Annulus by mean Diameter on CT

Proposed “Corrected” recommendations if using the mean of the long/short axis-

allow for 1-1.5 mm larger size

Imaging modality

and sizing criteria

Valve size chosen

23mm 26mm 29mm

*TEE guided 15 23 3

†MdCT unadjusted 5 26 10

MdCT using adjusted

criteria

13 23 5

Valve sizes were chosen from the MdCT mean of the basal ring but adjusted by 1.0 mm to account for the mean difference in this measurement from TEE, hence 23mm valve for annulus ≥19.5 to ≤22.5mm, 26mm valve for >22.5 to ≤26.5mm, and 29mm valve for >26.5 to ≤29.5mm

In press JACC Interventions

TAVR Strategy Modification

Left Main Height Assessment

Important Aortic root measurements Aortic measurements vary with individual valve specifications

Medtronic Corevalve has specifications regarding the height of the sinuses, the transinus dimension and the ascending aortic

diameter

The Sapien and Sapien XT do not require specifications of the sinus height

distance between the insertion of left coronary cusp and the left coronary artery ostium is important to predict risk of LM

occlusion

Left Main Height

No criteria exist to exclude patients on the basis of the risk

of coronary obstruction, but an 11-14 mm distance cutoff range has been proposed between the coronary ostia

and the leaflet insertion

Pay attention to the distribution and burden of calcification of the aortic valve cusps

Greater concern in the setting of heavily and diffusely

calcified cusps than localized calcification

Assessing the length of the left coronary cusp and its relationship to the height of the left main coronary

ostium may provide further

Left Main Height

Coronal oblique image in an 81 year old male and a 78 year old male patient the left coronary cusp and left coronary ostium is 16.2mm and 10.0 mm respectively

ILEOFEMORAL ASSESSMENT

Vascular Access Complications

ILIOFEMORAL ACCESS

Vascular complications have been reported and are largely attributable to

the large device size and significant atherosclerosis

Initial iliofemoral assessment with single plane angiography in the cath lab

MDCT allows assessment of a greater breadth of pathologies and anatomical structures

Minimal luminal diameter

Vessel tortuosity

Burden and pattern of calcification

Extent of atherosclerosis

Other high-risk features including dissections and complex atheromas

Thorough and complete three-dimensional assessment of the iliofemoral system

Iliofemoral Access- What We Know

Circumferential and/or horseshoe calcification in association with small caliber vessels or stenotic segments is considered a contraindication to a

transfemoral approach

may not allow the artery to expand to accommodate the large-profile delivery catheter

They also may increase the risk of arterial

dissection or perforation

Currently, alternative transapical or tranaxillary approaches should be considered in these patients

85 yo female- tortuous non-calcified iliofemoral arteries

X

Variable No vascular

complication

n = 58

Vascular

complication

n = 8

P Value

Minimal lumen diameter (mean) 7.0 6.2

Minimal lumen diameter < sheath

diameter, n (%)

23 (40%) 7 (83%) 0.02

Moderate or severe calcification, n (%) 9 (15%) 5 (42%) 0.04

[

Under revision JACC In press JACC

0

5

10

15

20

25

30

35

Minor (p=.02) Major (p<0.001)

2008

2009

2010

17% of patients screened with CT declined for procedure in 2010

Angle of Deployment

The need for multiple aortograms to define this optimal orientation increases procedural time,

contrast use, and radiation exposure

CT offers the potential to reduce the need for multiple angiograms and to provide guidance in

advance of the procedure

ANGLE OF DEPLOYMENT

Many potential angles representing the appropriate native aortic valve plane

Aortic valve is typically directed in a cranial and anterior fashion with angulation to

the right Caudal angulation -right anterior oblique

(RAO) projection and cranial angulation when in the left anterior oblique (LAO)

projection Significant variations across patients

Method for Co-Axial Angle Prediction:

Similar to the evaluation of the aortic annulus, double oblique transverse/ short axis multiplanar

reconstructions are performed

Points are deposited on the most inferior aspect of the aortic sinuses then connected to form a

triangle

3D volume rendered reconstruction of the aorta is then created with the triangle in place

Reconstruction is then rotated through a series of angles

ANGLE OF DEPLOYMENT

We aim to find angiographic projections representing perpendicularity to the native valve

plane in 3 axes:

1) AP cranial-caudal without RAO or LAO angulation

2) straight RAO to LAO as needed without cranial or caudal angulation

3) LAO 300 with cranial or caudal angulation as needed.

These axes were chosen based on the preferred working angles in the catheterization lab

Gurvitch, Leipsic et al. JACC Interventions Nov 2010

Predict Co-axial Angle of Deployment

CT to Assist Valve Deployment

Gurvitch R, Wood D, Leipsic J et al. MSCT for the Determination of the Angle of Deployment for TAVR. JACC Interventions. Nov 2010

Connect the Dots

Excellent-Superior struts

align perfectly Satisfactory – Superior valve

struts project within the height of

a cell

Poor –greater than the height

of a cell.

Line of Perpendicularity- Predicted Angles

MDCT vs 3-D Angio CT for Angle Prediction

CONCLUSION

TAVR therapy has seen rapid advancements over the last 5 years

Echocardiography has been commonly used for pre-procedural assessment and provides physiologic

data

MDCT can evaluate

3D annular and aortic root morphology and dimensions

Assessment of iliofemoral access

Procedural planning- angle prediction and left main height assessment