Minimally Invasive Mitral Valve Chordal Replacement Procedure Promising, but It’s Still Early Days
Very early results with a minimally invasive chordal replacement procedure suggest that the beating-heart, echo-guided procedure may emerge as another option for treating degenerative mitral valve disease with leaflet prolapse.
Details on the first 11 patients treated with the Harpoon TSD-5 device (Harpoon Medical) were published yesterday in Circulation.
The Harpoon TSD-5 device, delivered via a small thoracotomy, essentially mimics the surgical procedure that has been performed for 40 years, wherein artificial cords made out of expanded polytetrafluoroethylene (ePTFE)—better known as Gore-Tex—are used to correct mitral valve prolapse due to chordal rupture or elongation. Surgical mitral valve repair using ePTFE neochordae, however, requires cardiopulmonary bypass, aortic cross-clamping, cardioplegia, and thoracotomy or sternotomy and, as the authors of the current study point out, is associated with significant disability and risks as well as widely variable results.
As Harpoon inventor and the lead author on the paper James Gammie, MD (University of Maryland School of Medicine, Baltimore, MD) explained to TCTMD, the 3-mm shafted instrument is introduced transapically under transesophageal echo guidance. Concentric purse string sutures are placed on the epicardium at the insertion site, then the shaft component of the device stabilizes and perforates the underside of the leaflet using a specially designed 21-gauge needle, which delivers the Gore-Tex coils in a preformed knot configuration on the atrial surface. “Three or four” pairs of knots are delivered under beating heart imaging, then these tethers can be pulled back through the Teflon pledget on the ventricle to be titrated to the desired length “like marionette strings,” Gammie explained.
“In open surgery you’ll make your best guess estimate about how long the chords should be. And then you come off bypass and you think gee whiz, I wish I’d made them a little shorter or a little longer—I would have better coaptation,” he said. “But with this, you can titrate them in real time on the beating, loaded heart and can optimize exactly how long the chords are, and you can maximize coaptation, which we think will be associated with really great long-term results.”
First Patients, Early Results
Gammie et al’s paper reports 30-day outcomes in the first 11 patients to undergo the procedure at the University of Maryland School of Medicine and John Paul II Hospital in Krakow, Poland. All patients had posterior leaflet prolapse and severe mitral regurgitation and were low-risk candidates for surgery.
Chords were successfully placed in all patients during a total procedure time of 108 minutes, on average. No blood transfusions, intraoperative inotropic agents, or vasopressor support were required, and there was no perioperative stroke, new onset renal failure, postoperative A-fib, or myocardial infarction.
Two patients required reoperation for delayed pericardial effusion at 5 days and 13 days postop; both were discharged home “in good condition.” One patient was found to have symptomatic severe mitral regurgitation 2 months post-procedure and underwent open-heart surgery, which revealed that one of the three pairs of ePTFE chords had come untied from the epicardial apical pledget, although it remained tethered at the knot on the leaflet. The patient was discharged from the hospital after successful mitral valve repair and annuloplasty ring insertion.
“One of the things we would like to highlight is the fact that this procedure does not compromise the mitral valve leaflets, so in others words just putting a suture in the leaflet doesn’t cause any adverse effects,” Gammie said. “So unlike the MitraClip [Abbott Vascular] where you get a fibrous bridge and data suggests that an awful lot of those patients, when they come back, have to get a mitral valve replacement, we don’t think the Harpoon approach closes off any options.”
Gammie pointed out that the Gore-Tex material and procedure very closely mimic open-heart repair. “We know from a quarter century of experience with Gore-Tex that [the knots] don’t compromise the leaflet—they get incorporated into the leaflet over time but they don’t change the fundamental characteristics of the leaflet,” he said.
Minimally Invasive Chordal Repair
The Harpoon is only one of several devices exploring the potential of minimally invasive chordal repair for degenerative mitral valve disease—the frontrunner is the NeoChord’s Artificial Chordae Delivery System DS1000, which is also a transapical, beating-heart procedure. Last month, NeoChord got US Food and Drug Administration approval to start a prospective, multicenter, randomized clinical trial at 20 US sites led by David Adams, MD (Mount Sinai Hospital, New York, NY), and Michael Borger, MD (NewYork-Presbyterian Hospital/Columbia University Medical Center, NY).
Commenting on the Gammie paper for TCTMD, cardiovascular surgeon Francesco Maisano, MD (University Hospital Zurich, Switzerland), called the device “promising” but cautioned that “these data should be carefully evaluated before [causing] too much enthusiasm.”
Maisano pointed out that while the NeoChord device has been used in more patients and with positive results, the Harpoon device is smaller profile and would potentially lead to less trauma. Both approaches, however, are transapical and require thoracotomy, Maisano continued, whereas the MitraClip does not. Finally, in this early Harpoon experience, “they have been very selective in targeting a subpopulation of patients with relatively easy anatomy,” he said. “Overall I would maintain a quiet reaction until the device is used by more people.”
Also commenting on the study, Laura Mauri, MD (Brigham and Women’s Hospital, Boston, MA), made a similar point. “Unlike the EVEREST II randomized trial and high-surgical-risk registry that formed the basis for approval of MitraClip, this early study of the ePTFE insertion device enrolled relatively simple patients,” she said in an email. “Patients were required to have isolated posterior leaflet involvement [and] patients with functional MR or high STS scores were excluded (average STS score 1.2). Ultimately, we will want to know in this patient population suitable for surgical mitral valve repair whether this transcatheter approach can achieve similar results to surgery.”
That said, Mauri continued, while there are several approved transcatheter devices for aortic stenosis, there is only one for mitral regurgitation, “so this represents a very exciting area of investigation.”
Gammie, for his part, believes this particular approach to transapical, beating-heart mitral valve repair could be suitable in “a substantial majority of patients with degenerative disease and leaflet prolapse.” While the earliest cases were limited to those with posterior leaflet prolapse, “there’s no reason why we couldn’t treat patients with bileaflet prolapse” as well, he said. Moreover, while the procedure currently requires a surgeon and imager to lead the procedure, Gammie predicts that interventional cardiologists will be involved down the road. “One might imagine that in the not too distant future, there might be a way of accomplishing this percutaneously,” he said.
Of note, in December 2015, Edwards Lifesciences announced it had made a “structured investment” in Harpoon Medical that included upfront funds and an exclusive option to acquire the company in the future.
- Gammie J, Wilson P, Bartus K, et al. Transapical beating-heart mitral valve repair using a preformed ePTFE knot implantation device: initial clinical experience. Circulation. 2016;Epub ahead of print.
- Gammie, the founding stakeholder and inventor of the Harpoon device, reports ownership of stock and/or options in Harpoon Medical.
- Maisano reports serving as a consultant for Abbott, Valtech Cardio, Medtronic, Edwards Lifesciences, and St Jude as well as receiving royalties from Edwards. He is also the founder of 4Tech, Transseptal Solutions, and AFFix.
- Maurie reports institutional research grants from Abbott, Boston Scientific, and Medtronic.
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