Taboo-Bending Transcaval TAVR 1-Year Results 'Shockingly Mundane'

Patrice Wendling

March 04, 2019

One-year outcomes provide reassurance for the controversial use of transcaval access for transcatheter aortic valve replacement (TAVR).

Follow-up among the first 100 extreme-risk patients showed no major vascular complications or access-related clinical events between 30 days and 1 year.

No deaths in the first year were attributed to transcaval access and only one atrioventricular fistula was patent on CT at 1 year, the authors report today in the JACC: Cardiovascular Interventions.

"Transcaval access — crossing the retroperitoneal space to deliver a large sheath for whatever your procedure may be, a left ventricular assist device or transcatheter heart valve — is certainly feasible. There don't appear to be any long-term or late consequences of the access method and it is equally as safe as other alternative access methods," senior author Adam Greenbaum, MD, Emory University Structural Heart and Valve Center, Atlanta, told theheart.org | Medscape Cardiology.

"But maybe what's more unique than the overall message is don't be such a naysayer," he said. "For the advancement of science you have to think outside the box. And now we're using electrification of the wire for even more novel procedures, where we're splitting anterior leaflets of mitral valves with wires and splitting aortic leaflets."

What makes transcaval TAVR so provocative is that holes are intentionally made in both the aorta and inferior vena cava in the abdomen with an electrified wire. Because interstitial hydrostatic pressure is greater than venous pressure, blood exiting the aorta returns through the hole in the vena cava without accumulating as hemorrhage, Greenbaum explained.

This also allows large introducer sheaths to be withdrawn during tract repair with an off-label nitinol occluder device. The hole in the vena cava, however, is purposely left untended when the procedure is done.

The technique was developed at the National Institutes of Health (NIH) in 2011, with Greenbaum performing the first-in-human case in 2013 and early results from the first 100 patients reported in 2016. The vitriol was swift but since then more than 1000 transcaval TAVR cases have been performed worldwide, with 40 to 50 centers in the United States routinely using the technique, Greenbaum said.

The present study used serial contrast-enhanced CT follow-up to examine the longer-term fate of patients left with a large hole in the vena cava using the original 100 patients (mean age, 80 years; 58% female) who had no good conventional access options and an average STS predicted risk for mortality of 9.6% at baseline.

One-year mortality was 29%, with 21 deaths adjudicated cardiovascular and eight noncardiovascular.

This is comparable to the original PARTNER trial experience with TAVR in inoperable (31%) and high-risk (24%) patients, and higher than in the all-comer Society of Thoracic Surgeons (STS)/American College of Cardiology (ACC) Transcatheter Valve Therapy (TVT) registry, note the authors, led by Robert J. Lederman, MD, from the NIH's National Heart, Lung, and Blood Institute and coinventor of the transcaval technique.

Among 83 evaluable patients surviving beyond 30 days, 93% of fistulas were proven occluded on follow-up CT scans. Accounting for the competing risk for death, estimated occlusion rates were 33% postprocedure, 49% predischarge, 66% at 30 days, and 86% at 12 months.

"You can't CT people every month because there's radiation involved, so people underwent 30-day and also 12-month CTs. Does that mean it took 12 months to close? No, we just didn't study them until 12 months," Greenbaum said. "We see people close within hours, days. My guess is that most aorto-caval tracts close in 2 to 3 months."

As for the one patient with a patent fistula at 12 months, the occluder device was known to have been malpositioned and he died from a noncardiovascular cause at 618 days later without any sequela from the fistula.

No symptoms or adverse events were attributed to fistula patency status after the index transcaval TAVR, including the main theoretical late complications of heart failure admission and vascular or hemorrhagic complications.

Fistula status was not significantly associated with overall survival in multivariable analysis (hazard ratio, 0.71; P = .37).

"There may be no other more succinct summary of the 1-year outcomes of the transcaval registry: the concept simply works," James M. McCabe, MD, University of Washington, Seattle, writes in an accompanying editorial.

The "nearly banal outcomes" are unlikely to generate their own Twitter hashtags of "#TranscavalTerror" or "Fistula4Eva," he quips, but "let us not forget, however, that making any aspect of transcaval access seem banal is itself a remarkable achievement, considering the number of conceptual taboos and physiological misconceptions the technique gleefully disregards."

Nonetheless, barriers to widespread adoption, especially in healthier and younger populations, remain, including higher procedural costs, variable interdisciplinary politics, and concerning mechanisms to salvage true access disasters, McCabe says.

Although early results were strongly positive, he also notes that 35% of patients received blood transfusions during index hospitalization, 12% had major or life-threatening transcaval bleeding that met Valve Academic Research Consortium (VARC) 2 criteria, and 8% received a covered stent in the aorta.

"There's no doubt there were bleeding and vascular complications early on," but the study was started in 2014 when the investigators weren't sure about closure device choice or size, before steerable catheters were used to deploy the occluder more perpendicular to the aortic wall, and before they learned early administration of protamine helps with bleeding, Greenbaum noted.

"The other thing to keep in mind is that transfusion does not necessarily mean bleeding," he said. "If a patient came in with a hemoglobin of 8 and it was 7 after the procedure, they often got a unit of blood."

Notably, eight patients experienced aortic dissection during the procedure, including one fatal dissection caused by the CoreValve Evolut R delivery system and one asymptomatic dissection attributed to manipulation of the introducer sheath or the occluder device.

"The good news is that most dissections healed," Greenbaum said. "And the results were achieved with a repurposed Amplatzer nitinol occluder, with no cases of device fracture," despite half of the patients being treated by operators with little or no transcaval access experience.

A dedicated transcaval closure device (Transmural Systems) has been developed and demonstrated 75% immediate hemostasis of the aorto-caval tract in an early feasibility study in 12 patients in the United States, he noted.

"Whether or not it ever steps forward to reach the early majority and become de rigueur in cath labs providing large-bore access therapies, the concepts that underpin transcaval access are shockingly innovative and the long-term safety outcomes appear shockingly mundane, in the best possible way," McCabe concludes in his editorial.

Greenbaum and colleagues have been advocating for inclusion of transcaval TAVR as a separate procedure in the TVT Registry, where data are currently collected under the "other access" heading.

The data in this category are "almost always transcaval" and the "next data collection form release will include a specific transcaval access data element," vice chair of the TVT Registry, John D. Carroll, MD, director of interventional cardiology, University of Colorado School of Medicine, Aurora, told theheart.org | Medscape Cardiology in an email.

The study was supported by the National Heart, Lung, and Blood Institute. Greenbaum has served as a proctor for Edwards Lifesciences, Medtronic, and Abbott Vascular; holds equity in and serves as a scientific advisor for Transmural Systems; and has received institutional research support from Edwards Lifesciences. McCabe reports no relevant relationships.

JACC Cardiovasc Interv. 2019;12:448-456 and 447-448. Abstract, Editorial

Follow Patrice Wendling on Twitter: @pwendl. For more from theheart.org | Medscape Cardiology, follow us on Twitter and Facebook.

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