Novel Percutaneous Technique May Allow for TMVR in Patients at High Risk for LVOT Obstruction

Intentionally tearing the anterior mitral valve leaflet may prevent one of the most serious and life-threatening complications of transcatheter mitral valve replacement (TMVR)—left ventricular outflow tract (LVOT) obstruction—and enable operators to safely perform the procedure among patients with no other options, according to first-in-human research.

Because surgery is out of the question for some patients with severe mitral valve disease, interventionalists have been trying to adapt other currently available percutaneous treatments for off-label use in this population. But progress has been slow. Preemptive alcohol septal ablation has been used in patients at particularly high risk of LVOT obstruction, but this comes with its own risks and forces up to a 6-week delay of TMVR. Surgical resection of the anterior mitral valve leaflet combined with TMVR is another, albeit risky, avenue.

Researchers led by Vasilis Babaliaros, MD (Emory University Hospital, Atlanta, GA), have developed a novel percutaneous method aimed at preventing LVOT obstruction in TMVR-eligible patients. Called LAMPOON, the technique resembles a surgical maneuver to lacerate the leaflet with chordal sparing so that when the transcatheter heart valve is placed, blood continues to flow unobstructed.

In the April 24, 2017, issue of JACC: Cardiovascular Interventions, Babaliaros and colleagues report their initial experience with the technique in five patients who were previously deemed ineligible for surgery and TMVR at two US institutions. Using general anesthesia and intraprocedural transesophageal echocardiography, operators successfully performed the LAMPOON technique in all patients, immediately followed by TMVR with Sapien 3 devices (Edwards Lifesciences).

“Remarkably,” the authors report, “no patient exhibited a change in heart rate or blood pressure in the short time interval between LAMPOON mitral laceration and TMVR.” 

Afterward, all five patients were observed to have blood flow across the transcatheter heart valve struts from the left ventricular inflow into the LVOT. One patient died 23 days later as a result of intractable right heart failure that did not improve after TMVR, but the other four survived past 1 month. The researchers did not observe any procedural strokes, clinically significant paravalvular leaks, or major bleeding or vascular complications.

“The LAMPOON technique is important because 9% to 22% of patients selected to undergo TMVR in annuloplasty rings or native [mitral annular calcification] experience critical LVOT obstruction,” Babaliaros and colleagues write. “At present, at least one-third of patients seem to be excluded from TMVR out of predicted risk of LVOT obstruction caused by the displaced [anterior mitral valve leaflet]. LAMPOON may allow TMVR in most, or perhaps all, such excluded patients when using commercially available (uncovered) aortic [transcatheter heart valve] devices off-label.”

Additionally, “long or redundant native mitral leaflets,” as were seen in three of five patients in this study, have been known to affect the function of a transcatheter valve, they say. LAMPOON “may prevent this . . .  dysfunction by displacing the split mitral leaflet.”

Babaliaros and colleagues are planning a phase II study of the LAMPOON strategy in an estimated 60 patients, but they say this technique should also “inform development of future dedicated TMVR devices.”