Background: The impact of nodular calcifications in left ventricular
outlow tract (LVOT) and aortic annulus on the procedural outcome of transcatheter
aortic valve implantation (TAVI) with new-generation devices is yet to be
elucidated. Similarly, computational simulations may provide a novel insight into
the biomechanical features of TAVI devices and their interaction with nodular
calcifications. Methods: This retrospective single-center study included
232 patients submitted to TAVI with Evolut-R (53.4%), Portico (33.6%) and Lotus
(13.0%) devices with available preoperative computed tomography (CT) angiography
and evidence of nodular calcifications in aortic annulus and/or LVOT.
Calcification severity was defined moderate in presence of at least
two nodules or one nodule 5 mm. Three virtual simulation models of
aortic root presenting a nodular calcification of increasing size were
implemented. Stress distribution, stent-root contact area and paravalvular
orifice area were computed. Results: At least moderate calcifications
were found in 123 (53.0%) patients, with no sex differences. Among the
moderate calcification group, lower device success rate was evident
(87.8% vs. 95.4%; p = 0.039). Higher rates of moderate
paravalvular leak (PVL) (11.4% vs. 3.7%; p = 0.028) and vascular
complications (9.8% vs. 2.8%; p = 0.030) were also observed. Among the
Evolut-R group, higher rates of at moderate PVL (12.1%) were observed
compared to Portico (3.8%; p = 0.045) and Lotus (0.0%; p =
0.044) groups. Calcification of both annulus and LVOT (odds ratio [OR] 0.105;
p = 0.023) were independent predictors of device success. On
computational simulations, Portico exhibited homogeneous stress distribution by
increasing calfications and overall a larger paravalvular orifice areas compared
to Evolut-R and Lotus. Evolut-R showed higher values of average stress than
Portico, although with a more dishomogeneous distribution leading to greater
paravalvular orifice areas by severe calcifications. Lotus showed overall small
paravalvular orifice areas, with no significant increase across the three models.
Conclusions: At least moderate nodular calcifications in the
annulus/LVOT region significantly affected TAVI outcome, as they were independent
predictors of device success. Lotus and Portico seemed to perform better than
Evolut-R as for device success and moderate PVL. Computational
simulations revealed unique biomechanical features of the investigated devices in
terms of stent compliance and radial force.