Benefit of endovascular intervention sustained in patients with lower-extremity PAD

HOLLYWOOD, Fla. — Regardless of the severity of lower-extremity peripheral artery disease, peripheral vascular interventions including atherectomy, balloons and stents yielded positive outcomes at 6 months, according to new data from the LIBERTY 360° trial.

In particular, at 6 months, patients who received peripheral vascular interventions demonstrated a high rate of freedom from major adverse events and marked improvement in Rutherford classification, which is used to grade severity of PAD.

“LIBERTY 360° represents as close to a real-world experience with various endovascular strategies across Rutherford classes, many of whom would never be included in clinical trials, in particular Rutherford [class] 6 patients,” William A. Gray, MD, system chief of the division of cardiovascular services at Main Line Health, Wynnewood, Pennsylvania, said during a presentation at the International Symposium on Endovascular Therapy.

The prospective, observational study enrolled 1,204 participants with symptomatic PAD at 51 U.S. centers. Study physicians could use any endovascular devices that were FDA-approved for treatment of PAD during the study period. Enrollment was completed in February 2016.

Key findings

At ISET 2017, Gray presented 6-month data on 415 LIBERTY 360° participants in Rutherford class 2-3, 437 in class 4-5 and 55 in class 6. Generally, Rutherford classes 2-3 indicate claudication, classes 4-5 indicate critical limb ischemia and class 6 indicates the most severe form of CLI.

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Patients in Rutherford class 4-5 and 6 showed gradual and continued improvement from 30 days to 6 months, while patients in Rutherford class 2-3 maintained their 30-day improvement through 6 months, Gray said. Changes in Rutherford classification following peripheral vascular interventions were as follows:

Rutherford class 2-3: baseline, 2.8; 30 days, 1.3; 6 months, 1.4
Rutherford class 4-5: baseline, 4.5; 30 days, 3.1; 6 months, 2.3
Rutherford class 6: baseline, 6; 30 days, 5.5; 6 months, 4.6

Moreover, high rates of freedom from 6-month major adverse events — defined as death within 30 days of the index procedure, unplanned major amputation and clinically driven target vessel revascularization — was observed across all Rutherford classes.

Rutherford class 2-3: 92.6% freedom
Rutherford class 4-5: 81.2% freedom
Rutherford class 6: 73.7% freedom

The high rate of freedom from major adverse events at 6 months indicates that even patients in Rutherford class 6 can be treated with peripheral vascular interventions, Gray said during the presentation.

When components of the major adverse event outcome were examined separately, freedom from death was 97.1% in the Rutherford class 2-3 group, 95.3% in the Rutherford class 4-5 group and 85.1% in the Rutherford class 6 group; freedom from amputation was 99.8%, 96.8% and 87.1%, respectively; and freedom from clinically driven TVR was 93%, 83.1% and 85.1%, respectively.

Quality of life, as measured by the VascuQOL questionnaire, markedly improved across all Rutherford classes following intervention and through 6 months.

In other results, Gray also highlighted similar and low rates of severe angiographic and procedural complications in all Rutherford groups. Final post-procedure core lab-determined percent stenosis < 50% was 90.8% in Rutherford class 2-3, 83.8% in Rutherford class 4-5 and 76.6% in Rutherford class 6. Number of run-off vessels increased after peripheral vascular intervention; significant improvement was observed particularly in Rutherford classes 4-6, according to data presented.

Interventions used

Balloons and/or atherectomy were the preferred devices used for the patients enrolled in this study.

Use of specialty force/cutting balloons was significantly higher among patients in Rutherford class 6, while drug-coated balloons were more commonly used in Rutherford class 2-3. Use of scoring balloons was low overall.

Atherectomy with the Diamondback 360 Coronary Orbital Atherectomy System (Cardiovascular Systems Inc.) was the most commonly used strategy across all Rutherford classes, with significantly higher usage in Rutherford class 6 compared with the other classes. Laser atherectomy was also higher in the Rutherford class 6 group. The TurboHawk, SilverHawk and HawkOne devices (Medtronic/Covidien) were used in 10% or more of patients in the lower Rutherford classes, but less frequently in Rutherford class 6. Use of the JetStream Atherectomy System (Boston Scientific), Rotablator Rotational Atherectomy System (Boston Scientific), Phoenix Atherectomy System (Volcano Corp.) and the Crosser (Bard Peripheral Vascular) devices was lower and similar across classes.

Bare-metal stents were more commonly used than drug-eluting or covered stents, with a significantly higher use of bare-metal stents in Rutherford class 2-3.

A note of importance, Gray said, is that the penetration of drug-eluting therapies in general was relatively low at the beginning of trial recruitment.

Changing standard of care

LIBERTY 360° trial participants represent a challenging, difficult-to-treat population. The findings of this trial could establish a new standard of care for peripheral vascular intervention in patients with varying degrees of symptomatic PAD, according to Gray.

Gray told the audience at ISET 2017 that the 6-month data provide an interesting conclusion: “The results of this novel all-comers PAD study continue to suggest that peripheral vascular intervention is an alternative to ‘watchful waiting’ in Rutherford class 2-3 and ‘primary amputation’ in Rutherford class 6 — peripheral vascular intervention can be successful in these patient populations as well. … Peripheral vascular intervention could be considered for primary therapy in Rutherford class 6 patients felt to have a salvageable limb. … In addition, [these findings] provide further evidence to support peripheral vascular intervention treatment in Rutherford class 4-5.”

Participants of the LIBERTY 360° trial will be followed for up to 5 years. One-year results are anticipated later in 2017, according to a press release from Cardiovascular Systems Inc.

Reference:

Gray WA. Concurrent Session I: Peer Reviewed Abstract Presentations. Presented at: International Symposium on Endovascular Therapy; Feb. 4-8, 2017; Hollywood, Fla.

Disclosure: The study was funded by Cardiovascular Systems Inc. Gray reports financial ties with various medical device companies.