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

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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

Current Interventional Radiology-Related Benchmark Clinical Quality Measures Are Less Likely to be “Capped” Than Diagnostic Radiology Clinical Quality Measures

Clinical question
When contributing to the merit-based incentive payment system (MIPS) composite score under the Center for Medicare and Medicaid Services (CMS), are current IR-related clinical quality measurements (CQMs) more likely to be benchmarked and noncapped (worth the maximum 10 points) than DR-related CQMs?

Take away point
Significantly more IR-related CQMs are worth 10 points compared to DR-related CQMs, which can help mixed IR/DR groups maximize their MIPS composite score and thus their CMS payment adjustment.

Reference
Noor M, Bivins E, Manchek B, Contreras F, Shah R, and Ward T. Current Interventional Radiology-Related Benchmarked Clinical Quality Measures Are Less Likely to be “Capped” Than Diagnostic Radiology Clinical Quality Measures. J Vasc Interv Radiol. 2021; 32:677-682. doi.org/10.1016/j.jvir.2020.11.016

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Study design
Retrospective, database analysis using 2020 data from the quality payment program (QPP) resource library.

Funding Source
No reported funding.

Setting
Multi-database study using 2020 MIPS Historical Quality Benchmarks file, 2020 Cross-Cutting Quality Measures, and 2020 MIPS Quality Measure List; USA.

Figure



Cross-cutting CQMs identified as potentially applicable to IR periprocedural or clinic care and their respective MIPS point score based on benchmark and capped statuses.

Summary

The Quality Payment Program (QPP) under the Center for Medicare and Medicaid Services (CMS) aims to decrease healthcare costs by providing a payment system based on high-value care. Under the QPP, the merit-based incentive payment system (MIPS) generates a composite score (up to 100 points) to reflect the value-based care of a practice based on 4 essential performance categories: quality measures (QMs), improvement activities, cost, and promoting interoperability. In general, cost and promoting interoperability do not apply to radiology, and a radiology practice’s points from these categories are re-weighed to the QM category, which then accounts for 85% of the final MIPS composite score. In general, a practice can submit up to 6 different QMs for a total of up to 60 points. Three methods of QM submission exist: submission via MIPS clinical quality measurement (CQM) program, submission via electronic heath record (EHR) data as eCQMs, or submission via Medicare Part B claims if the practice is comprised of fewer than 15 clinicians.

Importantly, the MIPS composite score determines a percentage rate applied to future allowed charges via a minimum threshold (required to avoid a negative payment penalty) and a maximum threshold (above which a bonus is issued). These percentage rates and thresholds are becoming increasingly stringent, with CMS making annual changes based on prior years’ data. A CQM is considered “topped out” if it meets a national median performance rate of ≥ 95% and can be “capped” (decreased in point value from 10 to 7) if it has been topped out for 2 or more years. Given that 95% of specialty-specific QMs for DR were topped out in 2019 (the highest of any specialty) and 30% were capped, IR-related QMs could offer additional 10-point QMs to submit as contribution to a practice’s MIPS composite score. The authors perform a multi-database study analyzing the number and likelihood of IR-related QCMs worth 10 points compared to DR-related QCMs.

The 2020 MIPS Quality Measure List was used to identify measures directly attributed by CMS to DR and IR and those that might reasonably apply to IR periprocedural or clinical care. Additional cross-cutting measures that might apply to IR were identified via the 2020 Cross-Cutting Quality Measure file. Numeric identifiers were then cross-referenced with the 2020 MIPS Historical Quality Benchmark file to determine benchmark, topped out, and capped status. Only MIPS QCMs were included in the study; submission types via EHR and Medicare Part B were excluded.

Of the 713 QMs listed during the 2020 year, 196 were MIPS CQMs, 143 of which had a benchmark. Of the benchmarked CQMs, 9 were directly attributed to DR and 5 were directly attributed to IR (1 DR and 4 IR-related QCMs did not yet have a benchmark). Of these, 2/9 DR-related CQMs were not capped and 2/4 IR-related CQMs were not capped. An additional 6 cross-cutting measures and 2 potential IR periprocedural/clinic measures were identified, 7/8 of which were not capped.

Overall, 75% (9/12) of IR-related CQMs were worth 10 points (having both a benchmark and noncapped status) compared to 22% (2/9) of DR-related CQMs. This was a statistically significant difference with p=.03.

Commentary

The authors asses the number of IR-related and DR-related CQMs valued at 10 points in the context of the MIPS composite score. Since the quality measure category holds 85% of the weight in most radiology practice scores and a specialty is not limited to measures attributed to them by CMS, it makes sense to maximize this contribution by increasing overall practice scope with mixed IR and DR physicians.

The authors’ results show that only 2 of the DR-related CQMs can be submitted for 10 points and of those, one measure has already been topped out for 2 years, implying an imminent cap in 2021. Additionally, the other measure, which was uncapped in 2020 due to extenuating circumstances, may very well be recapped in 2021, which could result in zero DR-related CQMs being eligible for 10 points in 2021.

In comparison, there are up to 9 IR-related CQMs that can be submitted for 10 points, none of which have been topped out for 2 years. Of important note, most of the cross-cutting measures that the authors suggest do rely on either an having an IR clinic or performing specific procedures in order to qualify and submit them. Indeed, it is likely that many of the initially identified IR-related measures have yet to be benchmarked or capped because IR clinics remain to be established in many practices. Therefore, early development of IR clinic would prove advantageous in this setting, particularly for growing practices.

The main limitation of this study is that it focused solely on MIPS CQMs and excluded submissions via EHRs or Medicare Part B claims. Although EHR integration is necessary for eQCMs and only small practices may submit via claims, this study does lack validity and generalizability as a result of such exclusions.

Lastly, the authors highlight the need for medical societies to have increasingly robust measure-creation methodologies. This will likely rely on the creation of large, multi-center databases to identify gaps in care such as the Society of Interventional Radiology’s (SIR) VIRTEX data registry.

Post Author
Catherine (Rin) Panick, MD
Resident Physician, Integrated Interventional Radiology
Dotter Interventional Institute
Oregon Health & Science University

@MdPanick

Image-Guided Percutaneous Thermal Ablation of Oligometastatic Ovarian and Non-Ovarian Gynecologic Tumors

Clinical question
What is the role of percutaneous thermal ablation (TA) for secondary cytoreduction in patients with metastatic gynecologic tumors?

Take away point
TA is a reasonable option for secondary cytoreduction in patients with metastatic gynecologic tumors, with an overall survival rate of 37.5 months and a local progression-free survival rate of 16.5 months.

Reference
Image-Guided Percutaneous Thermal Ablation of Oligometastatic Ovarian and Non-Ovarian Gynecologic Tumors. Yuan, F.. et al. Journal of Vascular and Interventional Radiology, Volume 32, 729-738.

Click here for abstract

Study design
Retrospective, single-center, cohort study.

Funding Source
No funding

Setting
Single-center.

Figure

Summary

Metastatic gynecologic tumors unfortunately have a particularly low patient survival rate. Gynecologic tumors include ovarian, uterine/endometrial, cervical, and vaginal neoplasms. The current treatment recommendations to maximize cytoreduction generally include primary surgical resection, chemotherapy and radiotherapy. Overall, the residual tumor volume after primary surgical resection is the main prognostic factor in long-term survival. As with many image guided and minimally invasive procedures, TA results in shorter hospital stays, lower procedure related risks and is often better tolerated by patients who are not surgical candidates. The existing literature thus far has focused primarily on ovarian tumors that have metastasized to the liver. In addition, the role of secondary cytoreduction, such as TA, in gynecologic tumors, is not as well studied.

A retrospective, single-center, cohort study of 42 patients with metastatic gynecologic cancer was performed over two decades. All patients received primary surgical resection and chemotherapy. Over half received adjunctive radiotherapy. The most common treated tumor locations with TA were liver/liver capsule (74%), lungs (13%), and peritoneum (9%). The TA modalities used included radiofrequency, microwave ablation and cryogenic ablation. Following the procedure, patients either underwent contrast-enhanced-CT immediately after the treatment. If there was residual intratumoral enhancement and/or an incomplete zone of ablation, they were immediately re-treated. After successful treatment(s) the patients completed a contrast-enhanced-MR prior to discharge. Contrast enhanced-CT or MR was repeated one month post-treatment to evaluate treatment response. Adequate response to treatment was deemed as no intra or peri-tumoral enhancement. Patients were subsequently followed with repeat imaging every three months. Patients that were lost to follow-up or had indeterminate treatment responses were not included in their efficacy or survival analyses. Adverse reactions were based on the Society of Interventional Radiology reporting standards.

Local tumor control: Following the first TA treatments, the technical success rate was 95.6%; 109 targeted tumors had a complete tumor response. Two treated tumors had residual tumor on follow-up imaging and required a second ablation session. This lead to an overall primary treatment efficacy of 94.2%, with a mean follow-up period of 10 months. During this follow-up period, 8.5% (n=8/94) of the ablated tumors developed recurrence requiring additional treatments, of which 4/5 responded, resulting in a secondary efficacy of 80%.

Patient survival: The median survival following the initial ablation for all tumor types was 37.5 months (SE +/-; 95% CI, 27.7-47.3). Despite lacking statistical significance, the overall survival rate of metastatic ovarian tumors was 37.5 months (SE +/- 7.4; 95% CI, 23-52) and metastatic non-ovarian gynecologic tumors was 52.1 months (SE +/- 19.7; 95% CI 13.5-90.8). Time to progression in those with tumor recurrence was a median of 4.1 months (SD +/- 4.5 months).

Adverse events: The major adverse event rate was 4.8% (n=2/42). The major adverse events included: hepatic abscess (n=1), pleural effusion (n=1), chest pain (1), and small pneumothorax (1). All patients recovered well following appropriate standard treatment.

Commentary

This study explores the use of TA as secondary cytoreduction in patients with metastatic gynecologic tumors. A major limitation is that this is a retrospective and single-center study that spanned 20 years. Advances in chemotherapy, medical devices and standard of care likely have changed over that time-frame and may have affected outcomes.

Despite this study being one of the largest of TA and metastatic gynecologic tumors, there were still only 42 patients included. Subsequently, the non-ovarian subtypes of gynecologic tumors were small (e.g. n=5 for endometrial cancers) and therefore lacked comparative power. Although the tumors included in this study are all of gynecologic origin, they often have different prognostic factors, survival rates, chemotherapy and radiation regimens. Additionally, the overall five year survival rate varies greatly among patients with different gynecologic tumors and distant tumor spread. For example: ovarian epithelial=30%, ovarian-stromal=74%, cervical=17% and endometrial/uterine=17%.

Given the major differences in five year survival rates and treatment regimens, the greatest limitation is adequate interpretation of the survival benefits of this procedure. As mentioned previously, residual tumor after primary surgical resection is a major prognostic factor in long term survival. However, the role of secondary cytoreduction with TA is less clear. Based on different tumor-types, prior research has established that not all gynecologic tumors have survival benefits beyond chemotherapy. This leaves a few questions to be answered for future research. How does secondary cytoreduction affect survival rate in each gynecologic tumor sub-type? Do different tumor characteristics play a role in response? How does secondary cytoreduction with surgery versus TA compare in a prospective research setting? A larger, prospective, multi-center study may help clarify these findings and establish when secondary cytoreduction with TA is most appropriate. Despite the minimally invasive nature of TA, these patients often have a poor survival rate, so quality of life and judicial use of additional procedures and subsequent hospitalizations is of particular importance. Overall, this study provides an excellent foundation for further research and highlights TA as a useful tool in treatment of metastatic gynecologic tumors.

Post Author
Marissa Stumbras, MD

Interventional Radiology Resident, PGY2
Oregon Health & Science University
@MarissaStumbras