Preemptive Alcohol Septal Ablation May Help Prevent LVOT Obstruction in TMVR

First-in-human data give operators an additional option in treating this tricky patient population, a study author says.

Preemptive Alcohol Septal Ablation May Help Prevent LVOT Obstruction in TMVR

Preemptive alcohol septal ablation appears to lower the risk of life-threatening left ventricular outflow tract (LVOT) obstruction in select patients undergoing transcatheter mitral valve replacement (TMVR), according to a first-in-human study.

A surgical method of intentionally lacerating the anterior leaflet of the mitral valve, called LAMPOON, has already shown promise in this patient population, who often have no other treatment options and are traditionally excluded from clinical trials in this space.

Neither one of these methods is “foolproof,” but “until industry decides to build a better device . . . this is a workaround,” lead author Dee Dee Wang, MD (Henry Ford Health System, Detroit, MI), told TCTMD, adding that alcohol septal ablation might also be done to facilitate a LAMPOON procedure. “It's not 100% curative, but [alcohol septal ablation is] a new option that the average person who has experience in a high-volume [hypertrophic cardiomyopathy (HOCM)] site and has done HOCM alcohol septal ablation can empower themselves to do.”

The results were published in the July 8, 2019, issue of JACC: Cardiovascular Interventions.

Good Remodeling

Wang, along with Mayra Guerrero, MD (Mayo Clinic, Rochester, MN), William O’Neill, MD (Henry Ford Health System), and colleagues, retrospectively looked at 30 patients with severe mitral valve disease and at high risk for LVOT obstruction who received alcohol septal ablation before planned TMVR at six US centers between 2015 and 2018. All patients underwent preprocedural cardiac CT, and all had an estimated neo-LVOT—the gap between the transcatheter mitral valve and the native annulus—of at least 189.4 mm2.

Preemptive Alcohol Septal Ablation May Help Prevent LVOT Obstruction in TMVR
Photo Credit: Dee Dee Wang.
A) Pre-alcohol septal ablation three-chamber LVOT view on CT, red arrow denotes the thickened basal anteroseptal wall that would cause high risk for LVOT obstruction post-TMVR. B) Post alcohol septal ablation CT, green arrow shows the effacement and thinning of the basal anteroseptal wall of the LV and resultant larger neo-LVOT allowing TMVR implantation.

Based on postprocedural CT, the median increase in neo-LVOT surface area from baseline was 111.2 mm2 (P < 0.0001), but one outlier increased more than 200 mm2. “Not everybody's vessel is the same size, same caliber, or goes the same direction, so the response is varied,” Wang explained.

Overall, 19 patients underwent successful TMVR at a mean of 40 days after alcohol septal ablation. Of those who did not receive TMVR, two patients died before their scheduled procedure, eight patients weren’t treated due to clinical improvement, and one received surgical mitral valve replacement. Those who had transseptal (n = 15) and transatrial (n = 3) procedures all received Sapien 3 valves (Edwards Lifesciences), while the one patient who had transapical TMVR received the Lotus valve (Boston Scientific). One transseptal TMVR patient also received LAMPOON.

Median survival of the patients who received TMVR was 393 days. Thirty-day mortality was 5.3%, including one patient who died at 30 days due to complications from sepsis unrelated to valve function.

Most patients who are currently being turned down for TMVR due to risk of LVOT obstruction could be eligible for preemptive alcohol septal ablation, except for those who don’t have an engageable septal perforator or who have had prior CABG and an occluded left main coronary artery, Wang explained.

“The Achilles’ heel of this procedure is that it needs a wait period of about 2 weeks between the alcohol ablation and the repeat CT scan, primarily so that we can make sure their heart thinned out and remodeled appropriately,” she added, noting that some patients can’t always wait that long. Also, the pacemaker rate following alcohol septal ablation is known to be high—in this study, it was 16.7%.

Added Comfort

Commenting to TCTMD, Pinak Shah, MD (Brigham and Women’s Hospital, Boston, MA), called these findings “very exciting.” He said has used this technique in the past, but only because he had nothing better to offer. These data suggest there may be clinical benefit in appropriately selected patients, Shah observed. “I will definitely be much more comfortable about offering it to a patient if they meet all the other anatomical criteria.”

Preemptive alcohol septal ablation “is a lot less invasive than surgical approaches to this and actually something that I think most interventional cardiologists can do because it is not a terribly technically challenging procedure, where something like a LAMPOON is something that I think the average structural interventionalist is probably not going to get very facile with,” Shah observed. “I do think that most people involved in structural mitral interventions can get good at this and can do it safely.”

Wang also said they are using this technique more and more at her institution and recommended others “at least consider it and think of it as an option.”

Beyond concern over the pacemaker risk, Shah cautioned that this is “not a procedure that you're going to do and send the patient home the next day in most cases.” He also noted that the interventricular septums of many of these patients are not “generally super thick,” and so the delivery of too much alcohol could lead to a late complication of ventricular septal defect (VSD).

“The nice thing about this study is that they did look carefully at the interventricular septum in all these patients, and in no case was it really super thick. They were fairly standard-size septums and they still got very good results without any evidence of late VSDs,” Shah pointed out. “So I think that's encouraging and tells us that we can perform alcohol septal ablation safely in patients whose septums are otherwise normal size.”

Going forward, Shah said he would like to see a larger study including more centers in order “to understand whether or not this is something that can be safely done in a uniform way or whether it really needs to be limited to specific centers.”

Disclosures
  • Wang reports serving as a consultant to Edwards Lifesciences, Boston Scientific, and Materialise and has received research grant support from Boston Scientific.
  • Shah reports no relevant conflicts of interest.

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