Online Appendix
Computed tomography and echocardiographic methods
Computed Tomography
Patients underwent CT imaging prior to TAVR for annular sizing and after TAVR to assess THV geometry (1).
CT examinations were performed on either a 64-slice high definition scanner, Discovery HD 750 (GE
Healthcare, Wisconsin) or a Siemens Somatom Definition Flash Dual-Source scanner (Siemens Healthcare,
Erlangen, Germany). Heart rate reduction with beta-blockade was not performed. At St. Paul’s Hospital,
pre-procedural CT was performed with a contrast enhanced protocol using 80 to 120ml of iodixanol 320
mg/ml (GE Healthcare, New Jersey) at 5ml/sec followed by 30ml of normal saline. Post procedural CT was
performed using a non-contrast gated technique when the patient’s EGFR<45 ml/m2. With regards to postprocedural CT, owing to optimal image quality and a lack of difference in stent size and configuration
throughout the cardiac cycle due to the rigid stent structure, ECG gating was performed and measurements
were taken in diastole at 75 % of the R-R interval. Peak tube current (300 – 725 mA) and tube voltage (100
– 120 kVp) was based on body-mass index (body weight in kilograms divided by the squared height in
meters) and ECG-gated dose modulation was applied. For the scans from Aarhus University Hospital Skejby,
a different scan protocol using a contrast enhanced CT examination in the caudo-cranial direction with
retrospective gating was performed. Commercially available contrast media (Optiray 350 mg/ml) was used
(20 ml for the test bolus and 70 ml for the spiral scan). Contrast injection was followed by a 50 ml saline
flush. CT was performed with a 128 × 0.625 mm collimation, z-flying spot, gantry rotation time 280 msec,
and scan pitch 0.20 to 0.40 (depending on heart rate). Maximum tube current ranged from 450 to 750 mA
with fixed tube potential of 100 kV (body mass index [BMI] <30 kg/m2) or 120 kV (BMI >30 kg/m2). ECGcontrolled tube current modulation was applied with reduction of the current to 20% and full pulsing
applied only from 30-70% of the RR interval.
Pre-procedural Sizing
CT annular area measurements were performed in systole at 25% or 35% of the RR interval when the
annulus at its largest (2), depending on which of the two phase reconstructions displayed better image
quality. Recommendations for THV size were based on a CT sizing algorithm with an optimal goal of modest
annulus area oversizing (nominal THV area/CT annular area- 5% to 10%) (Table 1) (2). The algorithm
ensures routine oversizing of the CT aortic annular area (nominal THV area > CT annular area), calculating a
percentage of annular oversizing (nominal THV area/CT annular area). Nominal external THV areas for the
20-, 23-, 26-, and 29-mm SAPIEN XT THV are 3.14 cm2, 4.15 cm2, 5.31 cm2, and 6.61 cm2, respectively.
Implantation with nominally filled deployment balloons was performed by full injection of the indeflator
volume. When more than 20% area oversizing was anticipated or more than 10% oversizing in the presence
of adverse aortic root features balloon underfilling was proposed.
Post Procedure Scanning
To avoid the blooming and beam hardening effect of the cobalt-chromium stent frame, CT images were
reconstructed using both standard and hard convolution kernels. The stent frame of each THV was assessed
at 3 cross-sectional levels (inflow, mid-portion and outflow). The minimum external stent diameter, the
maximum external stent diameter and the external stent area were measured at each level by tracing along
the external margins of the stent frame. An experienced level 3 cardiac CT reader (JL) measured all stent
levels three times and the data represents the mean of the three repeated measurements. The CT
angiography reader was blinded towards the degree of underfilling in addition to all outcome measures of
this study including transthoracic echocardiogram (TTE), transesophageal echocardiogram (TEE), and ECG
results as well as clinical outcome data.
THV eccentricity was calculated as: 1 – minimum external stent diameter divided by the maximum external
stent diameter as measured by CT. A THV was considered non-circular, when the eccentricity was 10% or
more at all three levels of the stent frame (inflow, mid-portion and outflow).
THV expansion was defined as the CT-derived outer stent frame area divided by the nominal external valve
area. Under expansion was defined as an expansion ratio of 90% or less at all three levels (inflow, midportion and outflow). Actual CT area over sizing was defined as the CT-derived stent frame area divided by
the CT-derived native annular area.
Echocardiography
An intra-procedural TEE and post-procedural TTE were routinely performed by level 3 echocardiographers
to confirm annular measurements, to guide the THV deployment and to assess PVR, valve area and
transvalvular gradients. The grade of PVR was rated as none, mild, moderate, or severe according to VARC2 criteria (3).
REFERENCES
1. Leipsic J, Gurvitch R, Labounty TM, et al. Multidetector computed tomography in transcatheter
aortic valve implantation. JACC Cardiovasc Imaging. 2011;4:416-429
2. Gurvitch R, Tay EL, Wijesinghe N, et al. Transcatheter aortic valve implantation: lessons from the
learning curve of the first 270 high-risk patients. Catheter Cardiovasc Interv 2011;78:977-84
3. Kappetein AP, Head SJ, Généreux P, et al. Updated standardized endpoint definitions for
transcatheter aortic valve implantation: the Valve Academic Research Consortium-2 consensus
document. J Am Coll Cardiol 2012;60:1438-1454