IVUS Useful in Many Peripheral Intervention Scenarios, Consensus Document

The use of IVUS imaging can guide operators in a variety of clinical scenarios involving lower-extremity arterial and venous peripheral interventions, according to a new international consensus document. In writing, its authors faced a slim evidence base.

Currently, there has only been one publication of a RCT on the use of IVUS in peripheral interventions. That single-center study, published earlier this year, showed that compared with angiography alone, the routine use of IVUS changed treatment decisions in nearly 80% of cases and was associated with less binary restenosis at 1 year.

Acknowledging the gap in high-quality data, the document seeks to add the collective experience and opinion of dozens of vascular experts. The goal, said lead author Eric Secemsky, MD (Beth Israel Deaconess Medical Center, Boston, MA), is to provide a road map for the responsible adoption of IVUS in clinical practice.

“We felt that it was critical to come together to highlight where the consensus lies in terms of the use of IVUS during peripheral intervention, and also to highlight areas where IVUS can be important in improving outcomes similar to what we see in the coronary intervention space,” he told TCTMD. The multidisciplinary document included participants from all specialties that participate in the field. Representatives from interventional cardiology, interventional radiology, vascular medicine, and vascular surgery took part, with separate groups voting on appropriateness of IVUS for arterial and venous scenarios.

Among the recommended clinical scenarios where IVUS was judged “appropriate” were all femoropopliteal, tibial, and iliofemoral intraprocedural and postintervention situations as well as all preintervention tibial and iliofemoral situations.  While some preintervention iliac and femoropopliteal uses also received a recommendation of “appropriate,” others were judged “may be appropriate.”

“On the arterial side, it was quite prevalent that there was consensus that IVUS should be a much more routinely used adjunct for peripheral artery intervention,” Secemsky noted. “One thing that stood out was that among operators who are doing complex lower-extremity critical limb ischemia revascularization, in particular involving vessels below the knee, IVUS was unanimously supported as an adjunct in all phases of the revascularization procedure to help improve outcomes.”

Published online this week in JACC: Cardiovascular Interventions, the consensus document was accompanied by a separate paper that injects a note of caution about IVUS use, however, with post hoc data from the CAPSICUM trial suggesting a potential safety signal.

An editorial written by Debabrata Mukherjee, MD (Texas Tech University Health Sciences Center, El Paso, TX), and Christopher J. White, MD (University of Queensland and Ochsner Health System, New Orleans, LA), addresses both papers and urges operators to take heed of the unknowns: “For now, clinicians should consider IVUS or other adjunctive imaging as a useful part of their repertoire for selective peripheral arterial and venous interventional cases, but it is premature to recommend routine IVUS guidance for all peripheral interventional cases.”

Opinions ‘Fit’ With What Many Operators Believe

Led by Secemsky, the consensus document was created from the results of two anonymous surveys created by the 12-person writing committee: a 72-question survey on lower extremity arterial interventions and a 40-question survey on iliofemoral venous interventions.

For each clinical scenario, the interventional phases were broken down into preintervention, intraprocedure, and postintervention optimization. Each survey was sent to 15 vascular experts, such that a total of 30 experts from the United States, Australia, New Zealand, the Netherlands, and Germany were asked to grade the appropriateness of IVUS use in each scenario.

Regarding the tibial and iliofemoral questions, IVUS was deemed appropriate for all phases and clinical scenarios, including preintervention vessel sizing, minimizing contrast, determination of next therapeutic step, vessel sizing for device during the procedure, and stent optimization/postdilation.

For the femoropopliteal questions, only preintervention occlusion and plaque morphology received ratings of “may be appropriate for specific indication,” with all other femoropopliteal scenarios judged as “appropriate for specific indication.” The latter include: filling defects, preintervention vessel sizing, minimizing contrast, location of crossing track, determination of next therapeutic step, vessel sizing for device during the procedure, assessing residual stenosis/plaque after debulking postprocedure, stent optimization/postdilation, and detection of dissection.

To TCTMD, Secemsky said the results fit with what many vascular intervention specialists know, including how hard it is to size small vessels below the knee and how that can be improved with guidance from IVUS.

“Above the knee, when we looked at the iliac and femoropopliteal artery vessels, we still saw a really nice consensus that in the majority of situations, IVUS can be a useful adjunct during the procedure,” he added. “This is really highlighted by areas such as examining poststent implants, looking at dissections, and understanding residual disease.”

The document’s authors add that IVUS “is rarely associated with adverse events, and the safety associated with this device may have in part contributed to higher appropriate use ratings.” However, they acknowledge that more study is needed regarding whether the results are generalizable to other countries with restrictions on reimbursement for peripheral IVUS.

New Safety and Efficacy Questions Raised

In the same issue of the journal, investigators from Japan raise a potential safety issue in their analysis of the CAPSICUM trial. The data show a higher 1-year incidence of aneurysmal degeneration in symptomatic PAD patients who received a DES for femoropopliteal lesions when IVUS was used compared with when it was not used (19.8% vs 7.1%; P < 0.001).

The study authors, led by Takuya Tsujimura, MD (Kansai Rosai Hospital, Amagasaki, Japan), say that while “the exact mechanisms responsible for aneurysmal degeneration after femoropopliteal-DES implantation are unclear, vascular inflammation caused by sustained paclitaxel release, polymer, or the constant outward self-expanding force of the stent” can cause infiltration of CD3+ and CD56+ T cells. Another possibility, they say, is that IVUS use leads to selection of larger devices, which may increase the risk of vascular injury and aneurysmal degeneration.

In their editorial addressing both the consensus paper and the CAPSICUM results, Mukherjee and White say the frequency of aneurysmal degeneration in the IVUS group is “concerning.” They also point out that there was no difference in restenosis rates at 1 year in CAPSICUM in the IVUS versus no IVUS groups, which they say “raises concerns about the true effectiveness of IVUS” in peripheral interventions.

More evidence is anticipated soon from ongoing peripheral intervention RCTs studying IVUS, including IGuideU, iVEST, and DEVELOP. But in the meantime, Secemsky said many operators believe that there is sufficient enough data to recommend IVUS in agreed-upon situations and “move forward with how we're using this in our practices now, and not delay things for a trial that may not really change clinical practice.”

As for the issues raised by CAPSICUM, Secemsky pointed out that IVUS was used more often in patients with complex disease and that the study itself was underpowered. Further, he said the clinical impact of aneurysmal degeneration on a patient with symptomatic PAD is unclear, as is the explanation of how IVUS was the mediator between the intervention and the outcome.