OCT identifies scaffold edge vascular response after bioresorbable implant

A 3-year serial optical coherence tomography study demonstrated less luminal loss at the edges than luminal loss within the scaffold after implantation of an everolimus-eluting bioresorbable vascular scaffold.

“Although studies using intravascular ultrasound have evaluated the edge vascular response in metal stents and bioresorbable scaffolds, there is a lack of OCT-based in-scaffold vascular response and edge vascular response assessment after bioresorbable scaffold implantation,” researchers wrote.

The analysis focused on 40 patients from the ABSORB Cohort B study who were implanted with an 18-mm everolimus eluting bioresorbable scaffold (Absorb BVS, Abbott Vascular). Researchers studied 23 patients (23 lesions) from Cohort B1 who underwent OCT post-procedure at 6 months and at 2 years, in addition to 17 patients (18 lesions) from Cohort B2 who underwent OCT post-procedure at 1 year and at 3 years.

The researchers performed frame-by-frame OCT at the 5-mm proximal, 5-mm distal edge and 2-mm in-scaffold margins. They analyzed the middle 14-mm in-scaffold segment at 1-mm intervals, according to the study background information.

The researchers observed a significant decrease in in-scaffold mean luminal area from 7.22 ± 1.24 mm² at baseline to 6.05 ± 1.38 mm² at 6 months and from 7.64 ± 1.19 mm² at baseline to 5.72 ± 0.89 mm² at 1 year (P<.01 for both). In-scaffold mean luminal area was unchanged beyond 1 year.

The mean luminal area of the distal edge increased from 5.42 ± 1.81 mm² to 5.58 ± 1.53 mm² (P<.01) in Cohort B1. Mean luminal area of the proximal edge was unchanged at 6 months in this cohort.

The mean luminal areas of the distal and proximal edges were significantly smaller at 3 years compared with post-procedure measurements in Cohort B2.

Further, mean luminal loss at both the distal and proximal edges was significantly less than mean luminal area loss of the in-scaffold segment at 6 months and 2 years in Cohort B1 and at 1 year and 3 years in Cohort B2, according to the study.

“The luminal reduction of both edges is not a nosologic entity, but an edge vascular response in continuity with the in-scaffold vascular response, extending from the in-scaffold margin to both edges,” the researchers concluded.

Bill (Vasileios) D. Gogas, MD, PhD, and Habib Samady, MD, published an editorial comment noting that “in vivo multimodality imaging after bioresorbable scaffold implantation has provided important insights into the biological and mechanical properties of this novel revolutionary technology.

“In-scaffold and edge vascular response evaluated by light-based imaging at 3 years demonstrate a favorable pattern of tissue proliferation that does not significantly differ from that of conventional drug-eluting stents. However, after almost a decade of intense clinical and translational research within this space, the ongoing phase 3 and 4 clinical trials with intermediate-term outcomes are designed to demonstrate noninferiority and not superiority of bioresorbable scaffolds compared with third-generation DES. The promised advantage of the bioresorbable scaffold remains the potential for long-term superior outcomes resulting from gradual scaffold resorption and a more favorable short- and long-term biochemical and vascular response,” Gogas and Samady, from the Andreas Gruentzig Cardiovascular Center, Emory University School of Medicine, wrote.

For more information:

Gogas BD. J Am Coll Cardiol Intv. 2014;7:1370-1373.

Zhang YJ. J Am Coll Cardiol Intv. 2014;7:1361-1369.

Disclosure: The study was sponsored by Abbott Vascular. Several researchers report financial relationships with device and pharmaceutical companies, including Abbott Vascular. Gogas reports no relevant financial disclosures. Samady reports receiving a research grant from Abbott Vascular.