PROMISE-ing Updates for Percutaneous Deep Vein Arterialization

Six-month updates from a study in transcatheter arterialization of deep veins for the treatment of chronic limb-threatening ischemia (CLTI) were given on Tuesday by Miguel Montero-Baker of the Houston Methodist DeBakey Heart & Vascular Center in Houston, Texas.

Dr Montero-Baker began with a general introduction to the "no-option" patient with CLTI.

“Approximately 4 million people in the United States have CLTI, and within this population, there is a segment for whom standard surgical and endovascular revascularization attempts are inadequate,” he said. “As a result, these patients are left with no viable options to salvage their leg.

“According to the American Heart Association, the United States performs approximately 150,000 amputations annually. The burden of CLTI for patients includes a reduced quality of life, increased hospitalization rates, and higher health care costs, particularly for no-option patients at the severe level. This burden continues to grow due to the rising prevalence of diabetes and end-stage renal disease.”

With an eye on tackling CLTI, transcatheter arterialization of the deep veins is a technique with a lot of potential. The concept itself is not actually new – the earliest documented venous arterialization procedure was performed in 1881 by Francois-Frank – but it has been refined over time at certain milestones, such as in 1984, when Lengua published a book describing the modern procedure. “Then, vascular intervention experts like Roberto Ferraresi have been refining the technique, and LimFlow has developed a purpose-built system of devices to standardize this therapy as a fully endovascular option,” said Dr Montero-Baker.

The LimFlow System consists of a series of purpose-built devices, including artery-to-vein crossing catheters, a retrograde valvulotome, and tapered and straight stent grafts. The 6 Fr ARC arterial crossing catheter features a long crossing needle with a reach of 10 mm. The 4Fr V-Ceiver venous catheter incorporates a 6 mm self-expanding nitinol basket that creates a radiopaque target for arteriovenous alignment and wire capture for arteriovenous crossing. The retrograde Vector valvulotome is designed to atraumatically lyse the valves below the crossing point and into the foot to facilitate forward blood flow. The tapered crossing stent is optimized for sizing both the artery and vein, while the straight extension stents maximize outflow to the foot by preventing smaller veins from redirecting flow back up the leg.

Touching on the learning curve for the device/procedure, Dr Montero-Baker continued: “The LimFlow procedure itself is quite manageable since it utilizes devices and techniques commonly employed in most endovascular practices. However, new users must familiarize themselves with pedal venous anatomy and feel comfortable identifying and accessing veins in the bottom of the foot using ultrasound. Post-procedure patient management necessitates close collaboration with multidisciplinary care providers to ensure appropriate patient care. Wound care providers should be aware that primary closure of minor amputations is not recommended, and closure should be deferred until after tissue granulation.”

The PROMISE II Trial (Percutaneous Deep Vein Arterialization for the Treatment of Late-Stage Chronic Limb-Threatening Ischemia)¹ US pivotal trial is investigating the safety and effectiveness of the LimFlow System for creating an arteriovenous connection in the below-the-knee (BTK) vascular system using an endovascular, minimally invasive approach to arterialize the pedal veins for the treatment of CLTI in subjects ineligible for conventional endovascular or surgical limb salvage procedures.

“All patients were Rutherford 5/6, and were determined by an independent committee of vascular surgeons to have no endovascular or surgical options for intervention, leaving major lower-limb amputation as the only alternative,” noted Dr Montero-Baker, who relayed 6-month outcomes from PROMISE II.

Amputation-free survival rate was 66%, limb salvage rate 76%, and wound healing rate was 76% (healed or healing). Other procedural success measures included 99% technical success. Approximately one-third of patients required circuit maintenance.

“In terms of adverse events, among patients with CLTI and no option for revascularization who underwent transcatheter arterialization of the deep veins, nearly two-thirds were alive and free of above-ankle amputation at the 6-month follow-up, with no unanticipated safety concerns.”

In sub-analysis data looking at the difference in survival and limb salvage in the dialysis vs non-dialysis groups, the investigators observed lower survival in the dialysis group due to associated comorbidities. There was no statistically significant difference in limb salvage in the dialysis vs non-dialysis groups.

Looking forward, the plan is to now follow PROMISE II patients out to 3 years (safety). In addition, the prospective, single-arm, multi-center PROMISE III study is now underway and actively enrolling patients.²

“Transcatheter arterialization of the deep veins is safe and effective, and offers a potential new treatment option for patients facing amputation,” said Dr Montero-Baker in closing.

REFERENCES

1. PROMISE II Trial, Percutaneous Deep Vein Arterialization for the Treatment of Late-Stage Chronic Limb-Threatening Ischemia (PROMISE). ClinicalTrials.gov. Available at: https://www.clinicaltrials.gov/ct2/show/NCT03970538; accessed June 2023.

2. PROMISE III: Percutaneous Deep Vein Arterialization for the Treatment of Late-Stage Chronic Limb-Threatening Ischemia. ClinicalTrials.gov. Available at: https://clinicaltrials.gov/ct2/show/NCT05313165; accessed June 2023.