The effects of transcatheter aortic valvereplacement and conventional aortic valvereplacement on cardiac mechanics andfunction in patients with confirmed severeaortic stenosis. Insights from a nationalechocardiographic core lab
2020
Aortic Stenosis (AS) is a progressive disease characterised by increasing aortic valve
calcification and thickening, leading to escalating left ventricular afterload, and
myocardial damage. This sub-study of the UK TAVI trial investigated myocardial
functional recovery post-intervention in subjects with severe AS and intermediate
surgical risk, randomised to surgical aortic valve replacement (AVR) or transcatheter
aortic valve insertion (TAVI). Speckle tracking echocardiography (STE) was used to
assess the deformation of the myocardial wall (strain) in trans-thoracic
echocardiographic images (TTE’s). Strain was measured pre-intervention (baseline), 6-
weeks post-intervention(6W), and 12-months post-intervention (12M) in the left
ventricle (LV, n≤142), right ventricle (RV, n=25) and left atrium (LA, n=74). Additionally,
strain-volume loops were constructed to explore how the haemodynamic relationship
between volume and longitudinal strain in the LV changed pre- to post-intervention
after AVR and TAVI (n=48).
The improvement seen from baseline to 12M in TAVI was non-inferior AVR (P<0.05) for
LV global longitudinal strain, and LA maximum volume, pre-A volume, total emptying
fraction and active emptying fraction. Overall, there was evidence of global recovery of
the myocardium. Strain volume loops (SVL) for both AVR and TAVI saw a decrease in
LV end-diastolic volume at 12M compared to baseline, but only the TAVI SVL saw a
reduction in LV end-systolic volume. Overall systolic-diastolic uncoupling recovered in
both SVL’s but the changes in early vs late diastolic uncoupling varied between the
treatment groups; suggesting different myocardial changes. This work was limited by
the sample sizes for many of the analyses. A review of the UK TAVI image acquisition
and analysis procedures was performed, providing feedback regarding improvements
that may initiate greater quality TTE’s. Conclusions centred around improving
communication pathways and ensuring consistent training of staff. It has previously
been established that LV GLS is a sub-clinical predictor of heart function, and long-term
outcomes for patients with AS. LA volume is also a well-established predictor of
cardiovascular risk. Therefore, the findings of this work that recovery of both LV GLS
and LA maximum volume is non-inferior in TAVI compared the AVR suggest that the
long-term outcomes will also be non-inferior and supports the use of TAVI to treat
severe AS.
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