Characterization of Neurological Injury in Transcatheter Aortic Valve Implantation
Authors: Jonathon P. Fanning, Darren L. Walters, David G. Platts, Eamonn Eeles, Judith Bellapart, John F. Fraser
Journal: Circulation (2014)

T he application of transcatheter aortic valve implantation (TAVI) to high-surgical-risk and inoperable patients with severe aortic stenosis (AS) is gaining widespread acceptance with a burgeoning supportive evidence base. 1 The benefits associated with the application of this technique, however, are mitigated by the occurrence of major, disabling stroke with associated increased mortality and early-reduced quality of life. 2 Despite this, the risk/benefit ratio has been considered acceptable in appropriately selected patients given the outcomes of alternate management options in these high-risk and inoperable populations. 3,4he incidence of cerebrovascular events (CVEs) subsequent to TAVI exceeds that after any other cardiac intervention or valve surgery, most notably in the acute periprocedural period, diminishing over the subsequent 2 months. 5This elevated early risk reflects the increased incidence of ischemic stroke thought secondary to particulate emboli dislodged by the procedure itself or as a result of thromboembolism. 6n fact, cerebral embolism is a universal finding associated with these procedures. 7Most events, however, are subclinical or silent, with clinically apparent CVEs representing but the tip-of-the-iceberg.As a result of the difficulty ascertaining these subclinical events, the true association between TAVI and neurological injury is unknown and the harm potentially underestimated.This article aims to comprehensively review neurological injury in TAVI, with an emphasis on cerebrovascular disease.Evidence and current concepts regarding pathophysiological mechanisms, risk factors, and prognostic implications will be discussed and risk reduction strategies explored. Neurological ImpairmentCVEs post-TAVI are classified based on clinical severity as illustrated in Figure 1.Incomplete reporting and variable definitions of clinically apparent events and disregard of subclinical events have limited the true evaluation of CVEs associated with TAVI.Consequently, in 2011 the Valve Academic Research Consortium published a consensus report on standardized end point definitions, including stroke, which were expanded and refined in 2012. 8These criteria, as well as the important omissions of subclinical CVEs are listed in the Table. Clinically Apparent CVEs Overall IncidenceThirty-day stroke incidences reported in the major landmark TAVI studies and registries published to date are represented in Figure 2. 3,4,[9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Eggerbrecht et al 24 encompassed much of this within a meta-analysis of all TAVI studies published between January 2004 and November 2011.Here, the overall stroke rate was reported as 1.5% (±1.4%), 3.3% (±1.8%), 4.3% (±1.6%), and 5.2% (±3.4%) at 24 hours, 1 month, 6 months, and 1 year after the index procedure, respectively.A reduction in the attendant stroke incidence was anticipated as the TAVI procedure evolved, devices improved, patient selection processes became more refined, and stroke prevention strategies optimized.Much of the current literature reflects patients recruited, and data collected, from as far back as 2005, and has been criticized for not reflecting modern TAVI practices.In light of this, recent notable additions to the evidence base have included the second French national transcatheter aortic valve implantation