Results of the Valiant Mona LSA early feasibility study for descending thoracic aneurysms

Stent graft coverage of the left subclavian artery (LSA) may be required to achieve an adequate landing zone in up to 40% of descending thoracic aneurysms (DTAs). The Valiant Mona LSA Thoracic Stent Graft System (Medtronic, Santa Rosa, Calif) consists of a main stent graft and a branch stent graft designed to maintain LSA patency while diverting circulation through the encroaching aneurysm. Participating in the United States Food and Drug Administration's new Innovation Pathway, this first-in-human, early feasibility study evaluates early clinical experience of the Valiant Mona LSA Stent Graft System in patients with DTAs where the proximal landing zone necessitates LSA coverage.

This premarket, nonrandomized, single-arm prospective study recruited nine patients (age 72.9 ± 7.6 years). Primary end points were aneurysm-related mortality, stroke, paraplegia, left arm/hand ischemia, and treatment success. Neurologic events were assessed by imaging and by independent neurologists. Inclusion criteria required patients with a DTA or penetrating aortic ulcer to have a distance of ≥10 mm between the left common carotid artery and the LSA. Mean aneurysm diameter was 53.7 ± 10.0 mm. The indication for repair was for saccular DTA in five patients or fusiform DTA in four. Seven patients were at American Society of Anesthesiologists Physical Status Classification III/IV.

All nine patients received one main stent graft (diameter 28 to 42 mm) and one branch stent graft (diameter 10 to 14 mm). To extend device coverage distally, a commercial Valiant Captivia device was implanted in seven patients. No uncorrected endoleaks were observed at the end of the implant procedure. Four endoleaks developed before discharge in four of eight evaluable patients. Two were identified as type II and two were of undetermined type. No endoleak resulted in a secondary intervention. Technical success, defined by the clinical investigational plan, was achieved in all nine patients intraoperatively, and treatment success was achieved in all eight evaluable patients at 1 month. There were no major, disabling strokes. Four minor nondisabling strokes were reported in three patients ≤30 days (days 1, 1, 5, and 24). To date, there have been no reports of death, left arm ischemia, paraplegia, rupture, conversion to open surgery, or secondary endovascular procedure. No patients required surgical LSA revascularization.

The Valiant Mona LSA system demonstrates technical and treatment success, relative safety, and early durability in its initial use in DTA patients. Midterm results are expected as patients are monitored at regular intervals to 5 years.