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Transcatheter arterialization of the deep veins in patients with chronic limb-threatening ischemia appeared safe and led to limb salvage and wound healing in most cases, the PROMISE II study showed.

The procedure to turn a vein into an artery for no-option patients was successful in all but one of the 105 trial participants (99.0%), with a 66.1% rate of amputation-free survival at 6 months, which exceeded the performance goal.

Fully 76% of patients avoided above-ankle amputation, reported Mehdi H. Shishehbor, DO, MPH, PhD, of the University Hospitals Harrington Heart and Vascular Institute in Cleveland, and colleagues in the .

A quarter of wounds completely healed with use of the LimFlow System (16 of 63), and another 51% were in the process of healing.

It's a "novel -- if not audacious -- approach," wrote Douglas E. Drachman, MD, of Massachusetts General Hospital in Boston, in an .

In a simple but technically demanding procedure, the operator advances one catheter in the artery from the groin to the knee and another catheter from a vein in the foot to meet the other behind the knee, where the two vessels are mechanically connected with a needle, a guide wire, and covered stents. The vein below it effectively becomes an artery, providing oxygenated blood to ischemic tissues.

"This redistricting of the circulation, which diverts red oxygenated arterial blood flow into inherently blue deoxygenated veins, runs opposite to our understanding of how body circulation works," Drachman wrote, "however, the findings of the study indicate that this technique may offer substantial promise."

Current surgical and percutaneous approaches to critical limb ischemia work only in the arterial system, which requires an unobstructed vessel in the lower leg or foot on which to "land" the treatment, he noted. "However, in as many as 15% to 20% of persons with chronic limb-threatening ischemia, there is no landing point, owing to diffuse distal arterial disease, which precludes conventional revascularization."

The PROMISE II study included 105 patients (median age 70, 31.4% women, 42.8% Black, Hispanic, or Latino) with nonhealing ulcers and no surgical or endovascular revascularization treatment options as determined by a multidisciplinary review board, making major amputation likely.

The patients had predominantly Rutherford class 5 (tissue loss or focal gangrene; 68 patients) or class 6 (extensive gangrene; 37 patients) chronic limb-threatening ischemia. All were treated with the LimFlow System for the arterialization procedure in the single-arm study at 20 sites in the U.S. No unanticipated adverse device events occurred.

Outcomes were worse for the 19 patients (18.1%) receiving dialysis, with a 36.8% amputation-free survival rate at 6 months versus 72.7% among those without renal failure. Death from any cause occurred in 36.2% and 8.6%, respectively.

"Although the incidence of limb salvage was similar between patients who had dialysis-dependent chronic kidney disease and those who did not, mortality appeared to be greater in the population with dialysis-dependent disease," Shishehbor and colleagues noted. "The decision to offer transcatheter arterialization of the deep veins to patients with dialysis-dependent chronic kidney disease should take into consideration life expectancy and patient preferences."

The dialysis population may warrant additional study, and further exploration may be worthwhile overall to determine which patients may benefit most, Drachman suggested. "In addition, as other revascularization techniques evolve, what constitutes no-option arterial anatomy today may be surmounted in future years."

Another question is long-term outcomes for the 74.3% of patients who had prior unsuccessful revascularization procedures to maintain patency of the arteriovenous circuit.

"Whether ongoing vessel patency may be necessary to maintain limb salvage and whether venous congestion in the treated limb will attenuate long-term benefit are unknown," Drachman added. "Similarly, construction of the arterialized venous circuit requires a highly specialized technique that was performed by exceptionally proficient operators in this study. Will these findings be generalizable under conditions more akin to the real world with regard to operators, patients, and healthcare systems?"

Shishehbor and team noted that arterializing the deep veins is not a new idea, having been attempted in multiple surgical series starting more than a century ago, which were stymied by complications, including infection and trouble preventing diversion of blood flow away from the affected area from venous branches at the calf and ankle.

The transcatheter arterialization procedure addresses some of those limitations, although it took experienced interventional cardiologists and vascular surgeons trained on the procedure, which may limit it to use only at specialist centers.

Other limitations included the lack of a control group (since randomization of patients destined for major amputation was deemed practically and ethically unfeasible), follow-up limited to 12 months, and few patients dependent on dialysis. Also, enrollment through the pandemic meant 12 reported infections and five deaths were deemed related to COVID-19.

"Unresolved questions notwithstanding," Drachman concluded, "the establishment of a new option for reperfusion in advanced chronic limb-threatening ischemia offers potential promise for patients who would otherwise often be relegated to amputation."

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