Collagen-Based Bailout Compared to Suture-Mediated Vascular Closure Alone During Transcatheter Aortic Valve Replacement.

Background: Hemostasis for transfemoral transcatheter aortic valve replacement (TAVR) is typically achieved using a suture-mediated vascular closure device (VCD) prior to large-bore sheath insertion (preclosure technique). Recently, the addition of a hybrid closure technique using a preclose technique with the addition of a collagen-plug VCD after sheath removal in cases of failed hemostasis has been utilized. Methods: Data were collected from the Northwell TAVR registry, including 3 high-volume TAVR centers. We evaluated a preclose strategy with suture-mediated vascular closure alone ("legacy strategy") and standard bailout techniques versus a contemporary hybrid strategy of suture-mediated closure with collagen-mediated closure bailout. The primary end point was major or minor vascular complications as defined by the VARC-3 criteria. Results: A total of 1327 patients were included, of which 791 patients underwent TAVR with suture-mediated closure alone and 536 with contemporary strategy. The primary end point (major or minor vascular complication) was lower in the contemporary strategy (5.44% vs 1.31%; P < .001). Both minor (3.92% vs 1.12%; P = .002) and major (1.14% vs 0.19%; P = .0196) vascular complications were reduced and the total length of stay was less in the contemporary strategy (median of 3 days vs 2 days; P < .0001). Using multivariable analysis, we observed that vascular management strategy significantly improved the composite primary outcome when adjusted for sheath size, peripheral artery disease, carotid disease, and site of procedure. In the contemporary group, bailout collagen-plug VCD with an Angio-Seal (Terumo Medical) was used in 68 patients (12.69%) and bailout MANTA (Teleflex) was required in 4 patients (0.75%). There were no major or minor vascular complications among the patients who received bailout collagen-plug VCD. Conclusions: A contemporary hybrid strategy of suture-mediated closure with collagen-mediated closure bailout reduces the risk of vascular complications among patients undergoing transfemoral TAVR.

Engineered transcription-associated Cas9 targeting in eukaryotic cells.

DNA targeting Class 2 CRISPR-Cas effector nucleases, including the well-studied Cas9 proteins, evolved protospacer-adjacent motif (PAM) and guide RNA interactions that sequentially license their binding and cleavage activities at protospacer target sites. Both interactions are nucleic acid sequence specific but function constitutively; thus, they provide intrinsic spatial control over DNA targeting activities but naturally lack temporal control. Here we show that engineered Cas9 fusion proteins which bind to nascent RNAs near a protospacer can facilitate spatiotemporal coupling between transcription and DNA targeting at that protospacer: Transcription-associated Cas9 Targeting (TraCT). Engineered TraCT is enabled when suboptimal PAM interactions limit basal activity in vivo and when one or more nascent RNA substrates are still tethered to the actively transcribing target DNA in cis. We further show that this phenomenon can be exploited for selective editing at one of two identical targets in distinct gene loci, or, in diploid allelic loci that are differentially transcribed. Our work demonstrates that temporal control over Cas9's targeting activity at specific DNA sites may be engineered without modifying Cas9's core domains and guide RNA components or their expression levels. More broadly, it establishes RNA binding in cis as a mechanism that can conditionally stimulate CRISPR-Cas DNA targeting in eukaryotes.