Novel Approach May Stave Off Post-TAVR Coronary Obstruction

Patrice Wendling

April 09, 2018

Intentional laceration of the aortic leaflet during transcatheter aortic valve replacement (TAVR) may prevent the rare but fatal complication of coronary artery obstruction, a first-in-humans study suggests.  

The procedure, called BASILICA, involves an electrified guidewire that traverses and lacerates the aortic leaflet in front of the coronary artery at risk for obstruction, so that the split leaflet splays out of the way once the valve is deployed.

Just two 6-French catheters are needed, but the technique does involve a number of steps that must be carefully followed, lead researcher Jaffar Khan, MD, from the National Heart, Lung, and Blood Institute, Bethesda, Maryland, told theheart.org | Medscape Cardiology.

"The biggest drawback is probably that it still needs to be a proctored case and that may limit the rapid adoption by a lot of people, but at this early stage that's probably a good thing," he said. "The greatest advantage is that it's a procedure that uses marketed, widely available devices and addresses the pathophysiology."

The researchers have used guidewire electrosurgery before in transcaval access for TAVR and in the anterior mitral leaflet to prevent outflow obstruction. They began testing BASILICA on the bench and in five pigs, where it was successful for both left and right coronary cusps.

The present study, published in the April 9 issue of JACC Cardiovascular Interventions, involved compassionate use of BASILICA in seven patients considered unsuitable for surgery and turned down for TAVR in CoreValve (Medtronic) and Sapien (Edwards Lifesciences) trials.

In six patients, bioprosthetic aortic valves had failed, and one patient had native aortic stenosis. High-risk features for coronary obstruction included a median coronary height of only 6.8 mm, left sinus Valsalva width of 24.3 mm, and a virtual transcatheter valve to coronary distance of 2.8 mm.

All attempted leaflets were successfully treated. All patients experienced severe aortic regurgitation after leaflet laceration, but no patient required hemodynamic support in the 8 to 30 minutes between BASILICA and valve deployment, or afterward, Khan reported.

There was no evidence of coronary obstruction, and no patient had more than mild paravalvular leak.

Transient sinus bradycardia requiring temporary transvenous pacing occurred in one patient. All patients survived beyond 30 days, with follow-up from 95 to 154 days.

"Such a pioneering study must be commended, as it represents an effort toward TAVR refinement and evolution, aiming to solve a procedure-related complication that still does not have a definitive solution," Azeem Latib, MD, and Matteo Pagnesi, MD, both from the San Raffaele Scientific Institute, Milan, Italy, write in an accompanying editorial.

Latib just published his own international registry study, as reported by theheart.org | Medscape Cardiology, in which delayed coronary obstruction was identified in 0.22% of 17,092 TAVRs and was associated with a 50% in-hospital death rate.

Both Latib and Khan note that prediction of coronary obstruction is still suboptimal and that preventive strategies, such as "chimney" stenting, or extending a stent beyond the coronary ostium, have shown poor long-term outcomes and can make reengaging a coronary artery extremely difficult after TAVR.

While BASILICA seems technically feasible, Latib cautions that the procedure carries some risks, including the potential for rapid hemodynamic collapse and collateral mechanical damage to surrounding structures. Laceration of heavily calcified leaflets may be particularly difficult and also increase the risk for cerebral embolization.  

Richard Jabbour, MD, Imperial College London, United Kingdom, lead author of the recent study by Latib, said BASILICA could be a potential solution to delayed coronary obstruction but that it requires expertise.

"It is extremely complex and, for example, if you were to lacerate both leaflets at the same time you'd need multiple access sites; so I think if anyone were to try the procedure they would need extensive training," he told theheart.org | Medscape Cardiology.

Notably, two leaflets were lacerated in one of the seven patients.

Typically, BASILICA does not require extra access beyond what is used for standard TAVR deployment, but double-leaflet laceration would require two extra arterial accesses, Khan said. "This does increase the complexity" and "could also increase the risk of access site complications, particularly if you're putting in larger sheaths than you normally would for a standard TAVR."

Both the researchers and editorialists say further evidence on the safety and efficacy of BASILICA is needed from a multicenter study currently enrolling 30 patients at high or extreme risk for surgery undergoing TAVR for valve-in-valve or native aortic valve failure.

Khan said he thinks BASILICA will prove particularly useful for valve-in-valve procedures as TAVR valves begin to fail but may also benefit those in what he called the "grey zone" for coronary obstruction risk. For example, patients with coronary heights of 10 mm to 12 mm or a virtual transcatheter valve to coronary distance of around 4 mm.

"We'll need to see how safe this procedure is in the medium  to long term from the trial results, but if it proves to be fairly safe then I think physicians may start using it in those grey zones where they don't want to risk immediate or even delayed coronary obstruction," he added.

Khan, Pagnesi, and Jabbour report no relevant disclosures. Latib reports serving on the advisory board of and consulting for Medtronic; receiving speaker honoraria from Abbott Vascular; and receiving research grants from Edwards Lifesciences and Medtronic.

JACC Cardiovasc Interv. 2018;11:677-689, 690-692. 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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