Imaging for Predicting and Assessing Patient Prosthesis Mismatch after AVR

Imaging for Predicting &
Assessing Patient-Prosthesis
Mismatch after AVR
Dr Koh Choong Hou
20 Aug 2019

JACC Cardiovasc Imaging 2019; 12(1): 149-162

What is PPM?
• Literally, a mismatch between the patient and implanted prosthesis
• Remember, Gradient (or Velocity) = Flow (volume per unit time) ➗
Area (AVA)
• Flow, in any given haemodynamic environment, is proportional to
metabolic needs
• Hyperdynamic states (high flow): anaemia, fever, thyrotoxicosis, exercise
• Resting metabolic requirements: size of the patient (obesity paradox BMI >
30kg/m2)
• Hence Velocity/Gradient increases when (1) flow increases, or (2)
area decreases

Why is PPM so important?
• 2-20% of AVR patients may have severe PPM (defined as indexed EOA
< 0.65cm2/m2)
• Patients with severe PPM:
• Worse functional class and exercise capacity
• Reduced regression of LVH
• More HF related rehospitalization
• Reduced medium to long term survival
• Faster structural degeneration of bioprosthetic SAVR
• TAVR (esp self-expanding version) a/w less PPM than SAVR, but >
pacemaker and PVR

Tasca G et al. Impact of valve prosthesis-patient mismatch on left ventricular mass regression
following aortic valve replacement. Ann Thorac Surg 2005;79:505–10.

Head S et al. The impact of prosthesis-patient mismatch on long term survival after aortic valve replacement: a systematic review and meta-
analysis of 34 observational studies comprising 27,186 patients with 133, 141 patient-years. Eur Heart J 2012;33:1518–29.

Fallon JM, DeSimone JP, Brennan JM, et al. The incidence and consequence of prosthesis-patient
mismatch after surgical aortic valve replacement. Ann Thorac Surg 2018;106:14–22.

Bleiziffer S, Eichinger WB, Hettich I, et al. Impact of prosthesis-patient mismatch on exercise
capacity in patients after bioprosthetic aortic valve replacement. Heart 2008;94:637–41.

Pibarot et al. Incidence and sequelae of prosthesis-patient mismatch in transcatheter versus surgical
valve replacement in high-risk patients with severe aortic stenosis: a PARTNER trial cohort A
analysis. J Am Coll Cardiol 2014;64:1323–34.

Takagi H, Yamamoto H, Iwata K, Goto SN, Umemoto T. A meta-analysis of effects of prosthesis-
patient mismatch after aortic valve replacement on late mortality. Int J Cardiol 2012; 159:150–4.

Kulik A, Burwash IG, Kapila V, Mesana TG, Ruel M. Long-term outcomes after valve replacement for
low-gradient aortic stenosis: Impact of prosthesis-patient mismatch. Circulation 2006; 114:I5553–8.

Bioprosthetic Valve Degeneration

Flameng W et al. Prosthesis-patient mismatch predicts structural valve degeneration in
bioprosthetic heart valves. Circ 2010;121:2123–9.

Dayan V et al. Predictors and outcomes of prosthesis patient mismatch after aortic valve replacement. J Am Coll Cardiol Img 2016;9: 924–33.

How to prevent PPM?
• Knowledge of size and model of prosthesis → reference against
published EOA values (EACVI 2016) → divide this EOA by patient’s BSA
Lancellotti P, Pibarot P, Chambers J, et al. Recommendations for the imaging assessment of prosthetic heart valves: a report from the European
Association of Cardiovascular Imaging endorsed by the Chinese Society of Echocardiography, the Interamerican Society of Echocardiography
and the Brazilian Department of Cardiovascular Imaging. Eur Heart J Cardiovasc Imaging 2016;17:589–90.

What to do if predicted iEOA = PPM?
1. Change to another model of prosthetic valve with larger predicted
iEOA
2. Enlarge aortic root / annulus to accommodate larger sized valve
(depends on anatomy of aortic root)
3. TAVR instead of SAVR
• Again, need to predict iEOA pre-op
• 3D TEE or MDCT to identify pts with small Ao annulus whereby mod-large
sized valve may be difficult even after debridement

TAVR – “1-size-fits-all”
• Final TAVR prosthesis size is determined by native annular size and not
TAVR size itself
• A single-size transcatheter valve can be implanted across a range of
different annular sizes, and expanded to fill the annular space
• Any given model/label size of a TAVR valve thus provides a larger EOA when
fully deployed in a larger annulus
• Reference the normal values
Hahn RT, Leipsic J, Douglas PS, et al. Comprehensive echocardiographic assessment of normal transcatheter
valve function. J Am Coll Cardiol Img 2018 Jun 13.

Imaging for Predicting and Assessing Patient Prosthesis Mismatch after AVR

Beware the Russian Doll
• Transcatheter valve-in-valve procedure for degenerative bioprosthesis
have shown positive results in functional, haemodynamic and clinical
outcomes
• However, if high gradient was due to PPM in the first place,
telescoping another valve inside the prosthesis will not solve the PPM
oKey is to distinguish etiology of elevated gradient: stenosis / valve
degeneration, regurgitation, PPM, or combination of above
oUsage of oversized non-compliant balloon to fracture pre-existing
bioprosthetic stent to accommodate larger TAVR valve
oNewer gen SAVR valves have expandable frame (e.g. INSPIRIS Resilia AV,
Edwards LifeSciences), which does not require frame breaking
oTAVR valve with supra-annular design: high implant depth (0-2mm below
bioprosth stent) may also help increase EOA post TAVR

Pibarot P, Simonato M, Barbanti M, et al. Impact of pre-existing prosthesis-patient mismatch on survival following aortic valve-
in- valve procedures. J Am Coll Cardiol Intv 2018;11: 133–41.

Simonato M, Azadani AN, Webb J, et al. In vitro evaluation of implantation depth in valve-in-valve using different transcatheter
heart valves. EuroIntervention 2016;12:909–17.

Simonato M et al. Transcatheter replacement of failed bioprosthetic valves: Large multicenter assessment of the effect of
implantation depth on hemodynamics after aortic valve-in-valve. Circ Cardiovasc Interv 2016; 9:e003651.

PPM Assessment & Differentials
• Potential causes of high gradient post-op
 Obstruction from pannus, debris, thrombus, vegetations
 High flow states
 Technical errors
• Assessment parameters:
 Leaflet morphology & mobility
 Doppler
 Serial changes during follow up

Leaflet morphology & mobility
• PPM: valve structure, morphology & mobility are normal; Bioprosth stenosis:
thickened (>2mm) and restricted movements
• Bioprosth thrombosis: diffuse hypoechogenic thickening
• Bioprosth calcific degeneration: irregular hyperechogenic thickening
• Cinefluoroscopy & ECG gated CT to assess leaflet motion, opening/closing angles

Lancellotti P, Pibarot P, Chambers J, et al. Recommendations for the imaging assessment of prosthetic heart valves: a report from the Euro-
pean Association of Cardiovascular Imaging endorsed by the Chinese Society of Echocardiog- raphy, the Interamerican Society of Echocardiog-
raphy and the Brazilian Department of Cardiovascular Imaging. Eur Heart J Cardiovasc Imaging 2016;17:589–90.

Doppler Parameters
• Accurate derivation of the EOA from continuity equation MANDATES
the precise measurements of LVOT diameter and position of PW
sample of LVOT VTI
 LVOT diameter measured from outer border to outer border of stent/ring
 PW sample immediately below apical border of stent (no opening/closing
clicks should be seen)
• Multi-modality imaging – CT measurement of LVOT area

Doppler Parameters
• Measured EOA difference
 If >0.3cm2 difference between measured and reference value → suspect
stenosis
 If >0.6cm2 difference between measured and reference value → sig stenosis
• Doppler Velocity Index (DVI): ratio of LVOT VTI to AV VTI
 <0.35 → mild to mod stenosis
 <0.25 → severe stenosis
• Ratio of accel time to ejection time
 <0.32 → PPM
 >0.32 → stenosis

Serial Changes
• Compare velocity and gradients to baseline measurements post op
(pre-discharge echo)
 Recommended 1 month post AVR
 PPM → at valve implantation →stable over time;
 PrAV stenosis → post op increase in gradient / velocity over time
• Post op increase in MPG, with stable or increase in EOA and DVI →
likely from systolic function recovery and improved flow (do not
misinterpret this as stenosis)
• Remember that PPM and PrAV stenosis are not mutually exclusive –
both can co-exist in the same patient

How to differentiate PPM vs Stenosis / Obstruction?

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Management of PPM
• Consider valve reintervention when
 PPM severe
 MPG > 30mmHg
 HF
 Drop in LVEF
• Options
 Re-do SAVR with larger sized prosthesis
 Transcatheter ViV with self-expanding valve and supra-annular design +
fracturing of first SAVR valve

Summary
• PREVENTION
• Understand PPM – strategize pre-operatively to avoid it by sizing the
prosthesis appropriately
• DETECTION
• Recognize PPM and differentiate it from valve stenosis
• INTERVENTION
• Emerging role of ViV TAVR in managing PrAV PPM

Causes of High MPG
Obstruction High Flow PPM Pressure
Recovery
Gradients ↑ ↑ ↑ ↑
DVI ↓ Normal Normal ↓
EOA ↓ Normal Normal ↓
iEOA ↓ Normal ↓ ↓
Change in EOA
or DVI over
baseline?
Yes No No No
Abnormal
leaflet motion
Yes No No No

Imaging for Predicting and Assessing Patient Prosthesis Mismatch after AVR

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