3.1 DCBs, Stents and Endografts in Lower Extremity Interventions: What is Best? Leave Nothing Behind or a Lesion Specific Approach?

These proceedings summarize the educational activity of the 17th Biennial Meeting of the International Andreas Gruentzig Society held January 30 to February 2, 2024 in Chiang Rai, Thailand.

Faculty Disclosures     Vendor Acknowledgments

2024 IAGS Summary Document

Statement of the problem or issue

We investigated the question of why success rates with lower extremity interventions decline as one moves down the arteries from the iliac to the superficial femoral (SFA), to the popliteal, and then below into the tibial arteries. We developed the hypothesis that there were histopathologic differences between these arteries, and these were, in part, responsible for the differences in success and failure.

Figure 1. Differences in morphology along the peripheral arteries of the extremity. From: JACC Cardiovasc Imaging. 2019;12:1501-1513.

The histopathology changes along the course of the arteries.¹ Above the knee there is intimal calcium, based on mechanisms that we're familiar with from the coronaries. Below the knee there are significant amounts of medial calcium. In between, there is a transitional zone. The medial microcalcification begins, at first very diffuse, but then it becomes punctate. Eventually, the media fragments. As you move into the tibial arteries, osteoblasts are present in the media, and osteophytes form, so there is active bone formation. There are two types of smooth muscle cells in the tibial arteries. One is a proliferative smooth muscle cell, and the other is a progenitor smooth muscle cell. So, when you see proliferation of smooth muscle cells into the lumen of the tibial artery, they're coming from the arterial wall. Formation of intimal calcium is much higher in the SFA, and it's much lower in the tibials. When you look at medial calcium, it's dominant in the tibial arteries. The proximal tibial may show some characteristics similar to the SFA, but it quickly transitions into more medial hyperplastic disease and medial calcification.

Gaps in current knowledge

Stents, even drug-eluting stents, have not been as successful below the knee as above the knee. The same is true for bioresorbable vascular scaffolds. The pathology of the arterial wall is different below the knee, with a dual smooth muscle cell system in the media, and when a stent is placed it excites an intense hyperplastic response with smooth muscle cell migration through the stent struts and into the lumen. Drug coated balloons (DCBs) have had better success below the knee since the antiproliferative drugs inhibit the hyperplasia and do not leave any residual mass behind like a stent does. While there are compelling data for the paclitaxel-coated balloons, data for the limus-family of drugs is not as extensive. Newer drug formulations and newer balloons are becoming available, and these will be tested in trials.

Possible solutions and future directions

At the present time the best approach is to leave nothing behind when possible.

References

1. Torii S, Mustapha JA, Narula J, et al. Histopathologic characterization of peripheral arteries in subjects with abundant risk factors: correlating imaging with pathology. JACC Cardiovasc Imaging. 2019;12(8 pt 1):1501-1513. doi: 10.1016/j.jcmg.2018.08.039. PMID: 30553660.