Hypoechoic Halo Imaging Findings Following Femoropopliteal Artery Stent Implantation: Risk Factors and Clinical Outcomes

Background: Hypoechoic peri-stent areas in duplex ultrasonography (DUS) (ie, "halo") have been noted following femoropopliteal artery stenting.

Objectives: This study sought to investigate the prevalence, risk factors, and potential safety implications of hypoechoic halos identified with DUS following stent implantation in the IMPERIAL (ELUVIA Drug-Eluting Stent Versus Zilver PTX Stent) and EMINENT (Trial Comparing ELUVIA Versus Bare Metal Stent in Treatment of Superficial Femoral and/or Proximal Popliteal Artery) trials.

Methods: The IMPERIAL and EMINENT studies of femoropopliteal artery stenting included polymer-based drug-eluting stent, nonpolymer drug-coated stent, and bare metal stent treatment arms. A dedicated DUS protocol was implemented for core laboratory assessment of halo presence at study follow-up visits. Logistic regressions were used to investigate risk factors for a halo sign and its impact on clinically driven target lesion revascularization and primary patency.

Results: Diagnostic DUS imaging from 659 patients was obtained at time points ranging from 6 months to 5 years post-stent implantation. Halo prevalence ranged from 20% to 35% of patients with diagnostic DUS and was present at all time intervals. Halos were identified surrounding all stent types. In analyses of patients with diagnostic imaging from at least 2 visits, halo presence typically persisted, with occasional cases of regression and development at later times. No statistically significant association was found for halo status (ie, halo vs no halo) on 1-year clinically driven target lesion revascularization (OR: 1.27; 95% CI: 0.70-2.30; P = 0.4240) or primary patency (OR: 0.68; 95% CI: 0.43-1.07; P = 0.0927).

Conclusions: A hypoechoic halo following a femoropopliteal stent procedure is a common occurrence associated with all studied stent types. The presence of a halo appears to be benign with no associated clinical sequelae or effect on target vessel revascularization rates within 1 year of stent implantation.