Variable rate of stroke after transcatheter aortic valve replacement with self-expandable valves: more doubts than certainties

This commentary refers to ‘Comparison of newer generation self-expandable vs. balloon-expandable valves in transcatheter aortic valve implantation: the randomized SOLVE-TAVI trial’ by H. Thiele et al., 2020;41:1890–1899.

Cerebrovascular accidents are one of the main adverse events in patients undergoing transcatheter aortic valve replacement (TAVR); their incidence is variable among the different studies, especially with the use of self-expandable valves (SEVs).¹

The compariSon of secOnd-generation seLf-expandable vs. balloon-expandable Valves and gEneral vs. local anaesthesia in Transcatheter Aortic Valve Implantation (SOLVE-TAVI) trial was a very interesting open-label, randomized, multicentre study, comparing two newer generation transcatheter prosthesis, the SEV (Evolut R, Medtronic Inc., Minneapolis, MN, USA) vs. the balloon-expandable valve (BEV) (Sapien 3, Edwards Lifesciences, Irvine, CA, USA) in high-risk patients.² The study was powered for equivalence (within a margin of 10%) of the primary endpoint, a composite of all-cause mortality, stroke, moderate or severe paravalvular leakage (PVL), and permanent pacemaker implantation. At 30 days, the rate of the composite primary endpoint was equivalent between SEV and BEV {28.4% vs. 25.9%; rate difference −2.51 [90% confidence interval (CI) −9.65 to 4.53]; P equivalence = 0.04}. Conversely, the individual components of the primary endpoint were numerically higher in the SEV group, with the exception of stroke [0.5% vs. 4.7%; rate difference 4.20 (90% CI 0.11–8.28); P equivalence = 0.003].

The rate of stroke in the BEV group was consistent with previous studies, whereas in SEV group it was extremely low.^{1  ,  3  ,  4} We agree with the authors that this could be a chance finding; nevertheless, as an absolute difference of only nine events emerged between the two groups, we think that more thorough considerations are needed.

As the working mechanism of implantation has been appointed as a possible explanation for the differences in stroke rates comparing SEV with BEV,⁴ the timing of stroke occurrence in the SOLVE-TAVI should be known with a focus on acute (<24 h) and sub-acute (<30 days) events to highlight the true peri-procedural events.

Furthermore, a higher risk of cerebrovascular events after TAVR in patients receiving post-dilatation has been described, for additional mechanical manipulation and for cerebral hypoperfusion related to rapid ventricular pacing.^{1  ,  5} In the SEV group of SOLVE-TAVI, the rate of moderate or severe PVL was only 3.4%, probably related to the use of the new generation device. However, it should be of interest to know the rate of post-dilatation, that, in the SEV group of the CHOICE study was 49.2%, with an overall stroke rate of 2.6% at 30 days.³

Finally, in the SOLVE-TAVI, baseline atrial fibrillation (AF) in the SEV arm was reported in 47% of the patients, a nearly doubled rate compared to previous studies comparing SEV with BEV as the CHOICE (24.8%)³ and the propensity match cohort of the CENTER-Collaboration (27%).⁴ Despite pre-existing or new-onset AF plays a central role in the risk of cerebrovascular events after TAVR,¹ the high baseline AF rate reported in the SOLVE-TAVI in the presence of a very low stroke rate² highlights the difficulties to explain the different findings in stroke occurrence among clinical studies.¹

Conflict of interest: M.F. received individual payment as consultant, for advisory board or as speaker at scientific congresses from: Astra Zeneca, Chiesi Farmaceutici, Biosensors, Bayer, Sanofi, Boeringher Ingelheim outside the submitted work. S.M. has nothing to disclose.

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