麻豆传媒

WASHINGTON -- Operators can avoid two feared complications of transcatheter valve replacement with upfront radiofrequency-based laceration of the aortic or mitral leaflets, according to two early feasibility studies presented here.

Done before transcatheter mitral valve replacement (TMVR), the transcatheter procedure prevented left ventricular outflow tract (LVOT) obstruction. In the LAMPOON study, procedural success as defined by LVOT gradients under 50 mm Hg and no emergency surgery or reintervention was 73% overall.

As a precursor to transcatheter aortic valve replacement (TAVR), leaflet laceration yielded 93% procedural success defined as successful TAVR without coronary artery obstruction, emergency surgery, or reintervention in the BASILICA study.

Both 30-person single-arm studies were presented by Jaffar Khan, BM BCh, of the National Heart, Lung, and Blood Institute (NHLBI) in Bethesda, Maryland, and Medstar Washington Hospital Center, during a late-breaking trial session at this year's . Khan holds patents for leaflet-lacerating catheter devices.

"These are pioneering techniques that will help facilitate both procedures, and enable more patients to be treated who otherwise would not be candidates. These are early iterations, concocted from various materials being used in off-label fashion, and I fully expect that we will have purpose-built devices to do these techniques in the near future," commented Paul Sorajja, MD, of the Minneapolis Heart Institute, who was not involved in either study.

LAMPOON in TMVR

Khan called LVOT obstruction a "common devastating complication" of TMVR and said that preventive strategies such as surgical trans-atrial leaflet resection and prophylactic alcohol septal ablation have largely been suboptimal, in contrast with what can be achieved with the LAMPOON technique.

This new technique calls for catheters and guidewires that provide focused radiofrequency energy splitting the anterior mitral valve leaflet down the midline. "The split leaflet coapts in diastole, preventing torrential MR [mitral regurgitation] prior to TMVR. The leaflet splays away from the LVOT after TMVR permitting flow through the open valve stent cells," according to the investigator.

The LAMPOON study enrolled patients considered at high risk for surgical valve replacement and at prohibitive risk of LVOT obstruction during TMVR, having a mean predicted neo-LVOT of just 81 mm². Median age was 76 years, and 73% were women.

Patients with all anatomies and calcium patterns were able to get the LAMPOON procedure, Khan said, adding that they also had a relatively high 93% rate of survival at 30 days (compared to the 38% reported with other approaches).

"The data from their LAMPOON investigation is certainly compelling, even with an early experience and relatively small numbers. LVOT obstruction following transcatheter mitral valve implantation is a complexity that when it occurs, can be difficult to treat and is also difficult to completely predict," Scott Lim, MD, of the University of Virginia Health System in Charlottesville, told 麻豆传媒.

Even so, mitral annular calcification patients still had 13% mortality at 30 days, Mayra Guerrero, MD, of Mayo Clinic in Rochester, Minnesota, pointed out. This is slightly lower or similar to the 16.6% observed in the MITRAL trial, in which similar patients got alcohol septal ablation 3 to 4 weeks before enrollment.

“I am not sure the type of intervention (septal reduction versus leaflet laceration) matters as much as the fact that a successful intervention was performed to reduce the risk of LVOT obstruction,” she told 麻豆传媒. **Guerrero was a MITRAL investigator but was not involved with LAMPOON or BASILICA.**

One major limitation of the procedure is that it cannot prevent obstruction from the valve skirt, according to Khan. "Large annuli, paravalvular leak, hemolysis, and high transmitral gradients still complicated mitral valve-in-ring and valve-in-mitral annular calcification using Sapien 3 valves," he added.

LAMPOON is a “complex procedure that should only be performed by highly experienced operators and/or under the guidance from experts in the field,” Guerrero cautioned.

BASILICA in TAVR

A cousin of the LAMPOON technique, BASILICA is a transcatheter procedure that splits aortic leaflets using radiofrequency energy to prevent the rare but "devastating" complication of coronary artery obstruction, as described by Khan.

"While we have even less ability to identify firm predictors of coronary obstruction, these investigators were able to avoid this complication in subjects thought to be high risk for it," according to Lim.

Eligible patients in the BASILICA study were at high or extreme risk for surgical aortic valve replacement and high risk for coronary artery obstruction. This was a group in which four out of five were women and 57% got TAVR for a failing bioprosthetic valve.

Investigators found a 70% rate of VARC-2 safety at 30 days, which was limited most commonly by major vascular complications (20%) and strokes (10%).

Guidewire traversal requires a calcium-free target, Khan noted. "BASILICA requires careful procedure planning and execution to align laceration in front of coronary ostium," he added.

BASILICA is an “elegant technique” that isn’t easy but can be “reproducible and teachable,” Guerrero commented.

Even if physicians "are likely" to perform BASILICA rather than risk a fatal complication, Khan suggested, moving forward, it's important that operators get better at predicting coronary obstruction risk. This will require high-quality CTs in a registry, he said at a CRT press conference.