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Friday, July 23, 2021

Predictive Factors for Restenosis Following Stent-Supported Endovascular Therapy with Intravascular Ultrasound Evaluation for Femoropopliteal Chronic Total Occlusion

Predictive Factors for Restenosis Following Stent-Supported Endovascular Therapy with Intravascular Ultrasound Evaluation for Femoropopliteal Chronic Total Occlusion


Clinical question
What are the predictive factors for in-stent restenosis (ISR) following stent-supported endovascular therapy (EVT) for femoropopliteal chronic total occlusion that can be determined with intravascular ultrasound (IVUS) evaluation.

Take-away point
Distal external elastic membrane area, plaque burden, subintimal passage with calcification, and use of a stent graft were all found to be associated with ISR after stent-supported EVT.

Reference
Kurata, N., Iida, O., Takahara, M., et al. Predictive Factors for Restenosis Following Stent-Supported Endovascular Therapy with Intravascular Ultrasound Evaluation for Femoropopliteal Chronic Total Occlusion. J Vasc Interv Radiol. 2021;32(5):712-720.e1

Click here for abstract

Study design
Retrospective observational study

Funding source
Self-funded or unfunded

Setting
Single institution, Kansai Rosai Hospital, Amagasaki, Japan

Figure


Summary


Femoropopliteal (FP) lesions make up a large proportion of symptomatic peripheral arterial disease (PAD), accounting for approximately half of causal lesions. Approximately 40% of these FP lesions are described as chronic total occlusion (CTO), necessitating revascularization procedures. While the most recent TASC II guidelines general recommend surgical management with bypass for CTO cases, endovascular therapy (EVT) is often employed in practice. This practice, however, is often complicated by in-stent restenosis (ISR). Intravascular Ultrasound (IVUS) has been demonstrated in recent years to be a useful imaging modality in evaluating certain characteristics of vascular lesions, particularly during FP-EVT.

In this retrospective observational study, the investigators sought to identify lesion characteristics found with IVUS during FP-EVT and further investigate which served as predictors for ISR. 251 patients with symptomatic PAD caused by FP-CTO lesions who underwent EVT with stenting over a 7-year period were analyzed. 276 FP-CTO lesions were included. The study only included patients with available IVUS data from EVT. Stenting was done with one or a combination of the following at physician discretion: Supera woven stent, Viabahn covered stent graft, or Eluvia or Zilver drug eluting stents, as well as a variety of bare-metal stents. Procedural success was defined as ≤30% residual stenosis without flow-limiting dissection and ≤10 mmHg pressure gradient. Follow-ups including ABIs and duplex ultrasound were conducted at 1 month, 3 months, and every 3 months following. ISR was defined as a peak systolic velocity ratio of >2.4, assessed using duplex US, or a reduction in arterial diameter of ≥50%, assessed using angiography. During all included EVT procedures, external elastic membrane (EEM) diameter, and area at distal and proximal healthy sites were evaluated and used to calculate a mean EEM. Plaque burden was defined as proportion of area occupied by plaque between proximal and distal margins. The following lesion characteristics were measured from IVUS images: presence of stent-margin dissection was recorded, as well as the stent symmetry index (minimum/maximum stent diameter), wire passage (intraluminal or subintimal), and extent of circumferential calcification (intraluminal approach group: no calcification, <180˚ calcification, and ≥180˚ calcification; subintimal approach group: with calcification (S-C), without calcification (S-nC). Incidence of ISR was determined and correlated to measured lesion characteristics from IVUS images.

Mean age of included patients was 75 years ± 9 with 27% of patients being female. Mean lesion length was 229 mm ± 89. 26% and 59% of lesions were classified as TASC II C and D respectively. There was no statistically-significant difference in distribution of different stents used between different wire passage routes. Over a mean follow-up period of 19 months ± 16, ISR was observed in 31% of treated lesions. The incidences of ISR were 22% ± 3, 36% ± 4, and 43% ± 4 at 1, 2, and 3 years of follow-up respectively. Subintimal wire passage in calcified lesions was associated with an increased risk of ISR with a hazard ratio of 2.857 (p = 0.001) compared to intraluminal passage in an uncalcified lesion. All other wire passage routes are not statistically different than this reference. Additional characteristics that were found on multivariate analysis to be predictive factors for and against ISR included the following: use of a stent graft (HR 0.134, p < 0.001), plaque burden (HR 1.100, p < 0.001), and distal EEM area (HR 0.898, p < 0.001). No other characteristics were predictive.

Commentary


This study demonstrated increased risk of ISR with increased degree of plaque burden and subintimal passage through a calcified lesion, as well as a decreased risk with larger distal EEM and use of stent grafts in FP-CTO lesions. Additionally, it demonstrated that extent of calcification did not significantly correlate to ISR risk with intraluminal wire passage. Of note, the ISR rates reported were lower than those previously published. Use of stent grafts in 32% of patients in this study and the concomitant decreased associated risk of ISR with stent grafts may be a significant reason for this. It is also notable that drug-eluting stents did not affect ISR rates despite their known efficacy, which may be attributable to the severity of lesions studied.

This study has multiple limitations, including small sample size, lack of independent IVUS evaluation, and limited measures. Specifically, only circumferential extent of calcifications was measured, without regard to thickness or length. Additionally, given the retrospective nature of this analysis, selection bias due to physician discretion in intervention options likely affected results. IVUS allows evaluation of vascular lesion characteristics not previously measurable with angiography alone. While this study demonstrates several predictive factors in severe FP lesions, generalizability is limited without larger studies. The investigation does demonstrate the utility of IVUS in identifying lesion characteristics for future research.

Post Author
Jared Edwards, MD
General Surgery Intern (PGY-1)

Department of General Surgery
Naval Medical Center San Diego, San Diego, CA

@JaredRayEdwards

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