Abstract
Background: Endovascular therapy (EVT) for severely calcified femoropopliteal (FP) lesions in patients with peripheral artery disease (PAD) is challenging. This study evaluates the clinical utility of rotational atherectomy and orbital atherectomy in EVT for such lesions.
Methods and Results: This single-center retrospective study enrolled 62 consecutive patients with symptomatic PAD (71.0% male; median age 76 years; diabetes 71.0%; hemodialysis 30.6%; chronic limb-threatening ischemia 27.4%) due to severely calcified FP lesions (chronic total occlusion 32.3%; average lesion length 150 mm; Peripheral Arterial Calcium Scoring System classification: grade 1, 6.5%; grade 2, 12.9%; grade 3, 22.6%; and grade 4, 54.8%) who underwent EVT with atherectomy systems. The luminal gain was evaluated using angiography and intravascular ultrasound (IVUS). Quantitative vascular analysis showed stenosis diameters of 86.6% (pretreatment), 48.4% (after atherectomy), and 25.5% (after adjunctive balloon angioplasty). IVUS indicated the minimum lumen area increased from 2.0 mm2
to 8.1 mm2
after atherectomy and 17.8 mm2
after angioplasty (P<0.001). Superficial calcium arcs decreased from 195.9° (141.6, 360) to 158.7° (119.9, 211.2; P<0.001). Procedural success was achieved in all patients. Distal embolization occurred in 7 patients. No major adverse events occurred within 30 days.
Conclusions: Atherectomy systems significantly increased lumen dimensions in severely calcified FP lesions by removing superficial calcium without increasing the risk of major complications. However, a notable incidence of distal embolism remains unavoidable.
As the population ages and the prevalence of diabetes and chronic kidney disease increases, the incidence of peripheral arterial disease (PAD) also increases. Approximately 70% of symptomatic patients with PAD have femoropopliteal (FP) lesions.1,2 In addition, calcified FP lesions are found in approximately 50–70% of patients and have adverse effects on both early and late outcomes.3
Drug-coated balloon therapy (DCB) plays a pivotal role in the endovascular management of FP lesions in the clinical setting. Several clinical trials of DCB have demonstrated a significant reduction in reintervention and restenosis rates; however, severe calcification remains a notable risk factor for recurrence.4 Atherectomy devices are useful for treating severely calcified FP lesions, and they potentially improve vascular compliance, modify calcified plaques, and decrease the risk of severe dissection and rates of bailout stenting and long-term target limb revascularization (TLR).5,6 In contrast, the latest European Society of Vascular Surgery (ESVS) guidelines state that complications, including distal embolism, are an issue in clinical practice and that atherectomy lacks superiority over conventional endovascular therapies in terms of efficacy and safety endpoints; thus, the routine use of atherectomy devices for the treatment of FP lesions is not recommended.7 In addition, the performance of calcified plaque removal using atherectomy has not yet been objectively evaluated. In this study, we used multiple modalities to investigate the extent to which luminal enlargement was achieved using an atherectomy device for severe FP lesions.
Methods
Study Design and Patient Enrollment
This was a single-center, retrospective, observational study. Between April 2023 and July 2024, 62 patients with symptomatic PAD due to significant severely calcified FP lesions who underwent endovascular therapy (EVT) with an atherectomy system (Jetstream, Boston Scientific, Marlborough, MA, USA, or Diamondback 360, CSI, Minneapolis, MN, USA) were included. The main inclusion criteria were severely calcified de novo, non-stented restenotic, or reocclusive FP lesions with a reference vessel diameter of 3–7 mm. In terms of indication for utilization of atherectomy device, we have followed the guidelines for proper use of the atherectomy device. The indications for atherectomy treatment included bilateral calcification identified via fluoroscopy and calcified lesions or nodules exceeding 180 degrees as assessed using intravascular ultrasound (IVUS), which were deemed challenging to dilate using stand-alone balloon angioplasty. The exclusion criteria were as follows: (1) lesions without calcification evaluated using fluoroscopy; (2) acute limb ischemia (ALI); (3) common femoral lesions; and (4) in-stent restenosis. In addition, 2 patients in whom the atherectomy system was not activated because of device kinking due to vessel tortuosity were excluded from the study. A detailed patient flowchart is shown in Figure 1. Although this was an observational study, treatment-associated complications, such as distal embolism and consequent lower leg amputation, were possible. Therefore, written informed consent was obtained from all patients in accordance with the ethical guidelines for medical research involving human subjects.
Ethics
The study protocol conformed to the ethical guidelines of the 1975 Declaration of Helsinki and was approved by the Institutional Review Board of Osaka Keisatsu Hospital (2124), who waived the need for informed consent for the study due to the retrospective study design.
Study Procedure
Preoperatively, all patients underwent ankle-brachial index (ABI) testing, arterial echocardiography, computed tomography (CT), and preliminary angiography to assess the anatomical severity and morphology of the lesions. The results were combined with digital angiography (DA) and IVUS. Antithrombotic medications, including aspirin, clopidogrel, warfarin, and direct oral anticoagulants (DOACs), were administered at the discretion of the physician, and significant aortoiliac (AI) disease was treated before FP lesion treatment. The procedure was performed via the common femoral artery (ipsilateral or contralateral) and 5,000 units of heparin were administered after the puncture in all patients. The lesion was crossed with a 0.36 mm guidewire and morphologically assessed using IVUS (Alta View, Terumo Corp., Tokyo, Japan). Two types of the rotational atherectomy (RA) system were used in this study. A 2.0 mm catheter was selected for the orbital atherectomy system (OAS), an XC2.4/3.4 mm was selected for the RA, and the lesion was excised. Pre-dilation was routinely performed with a conventional and/or scoring balloon, depending on the target vessel diameter, and DCB treatment was subsequently performed. Dilatation was performed for at least 3 min, according to the DCB package insert. If subsequent angiography revealed >50% residual stenosis and/or severe dissection, additional post-dilatation was performed with a scoring balloon or similar device. If an unstable plaque remained or vessel perforation occurred, a Viabahn stent graft (W. L. Gore & Associates, Flagstaff, AZ, USA) was used.
Definitions
Severe calcification was assessed bilaterally using fluoroscopy and graded in accordance with the Peripheral Artery Calcium Scoring System (PACSS) classification.8 Technical success was defined as the absence of severe dissection and residual stenosis of <50% (DCB or balloon only) or <30% (stent placement) after stent or drug-eluting balloon placement, as measured using quantitative vascular analysis (QVA) with geometric methods based on the PARC classification.9 Distal embolism was defined as angiography after atherectomy using an atherectomy system that showed a flow obstruction that required additional treatment such as catheter aspiration, removal with a Fogarty catheter, additional angioplasty, or catheter-directed thrombolysis.
Study Outcomes
The outcome measure was luminal gain, including minimum lumen area (MLA) and percentage of diameter stenosis (%DS), as assessed using IVUS and angiography. The %DS on angiography was evaluated using QVA with the geometric method and the minimum lumen diameter (MLD) and lumen symmetric index (LSI), as assessed using IVUS. CT evaluation of the extent of calcification volume reduction used the Agatston score as a reference, and significant calcification was defined as areas with CT values ≥130 HU for each slice. Atherectomy-related complications, including distal embolism and vessel rupture, and the relationship between the lesion calcification type (superficial, deep, or nodular) and distal embolism were evaluated.
Statistical Analysis
Continuous variables are presented as mean (interquartile range), and discrete variables are presented as numbers, unless otherwise stated. The primary efficacy endpoint was analyzed using non-parametric analysis for continuous variables, Wilcoxon rank-sum test for discrete variables, and Mann-Whitney U test for ordinal variables. Safety assessment items are presented as numbers, unless otherwise stated. The model was adjusted for superficial and calcified nodules. Mean differences are reported with 95% confidence intervals (CI). The association between distal embolization and atherectomy was evaluated using logistic analysis. Statistical significance was defined as P<0.05. All statistical analyses were performed using the SPSS software (version 29; IBM Corporation, Armonk, NY, USA).
Results
Patient, Lower Limb, and Lesion Characteristics
The demographic and procedural data, the limb and lesion data at baseline are shown in Table 1. The mean age of patients was 76 (70–82) years, and 71.0% were male. The notable risk factors included diabetes (71.0%) and end-stage renal disease requiring dialysis (30.6%). The preoperative ABI was 0.69 (0.5–0.8), and the most common Rutherford classification was 3, accounting for 54.8% of patients. For the TransAtlantic Inter-Society Consensus (TASC) classification, 9.7% were A, 33.9% were B, and 48.4% were C, whereas for the PACSS classification, 22.6% were grade 3, and 54.8% were grade 4. The mean lesion length was 150 (60–260) mm, and 32.3% of the lesions were chronic total occlusion.
Table 1.
Baseline Patient, Limb and Lesion Characteristics
| Variable |
n=62 |
| Patient characteristics |
| Sex, male |
44 (71.0) |
| Age (years) |
76 [70–82] |
| Body mass index (kg/m2) |
22.6 [20.5–26.1] |
| Non-ambulatory status |
0 (0) |
| Hypertension |
55 (88.7) |
| Dyslipidemia |
49 (79.0) |
| Diabetes |
44 (71.0) |
| Hemodialysis |
19 (30.6) |
| Smoking |
39 (62.9) |
| Coronary artery disease |
38 (61.3) |
| Cerebrovascular disease |
8 (12.9) |
| Atrial fibrillation |
9 (14.5) |
| Congestive heart failure |
8 (12.9) |
| Ejection fraction (%)† |
67 [59–71] |
| Laboratory data |
| Albumin (g/dL) |
4.0 [3.5–4.2] |
| Creatinine (mg/dL) |
1.06 [0.83–5.09] |
| LDL-cholesterol (mg/dL) |
69.5 [56.8–89.3] |
| HbA1c (%) |
6.7 [5.9–7.4] |
| Limb and lesion characteristics |
| Ankle-brachial index before index procedure |
0.69 [0.5–0.8] |
| Rutherford classification |
| 1 (mild claudication) |
1 (1.6) |
| 2 (moderate claudication) |
7 (11.3) |
| 3 (severe claudication) |
34 (54.8) |
| 4 (ischemic rest pain) |
4 (6.54) |
| 5 (tissue loss) |
15 (24.2) |
| 6 (tissue loss) |
1 (1.6) |
| TASC classification |
| A |
6 (9.7) |
| B |
21 (33.9) |
| C |
33 (53.2) |
| D |
2 (3.2) |
| History of EVT |
14 (22.6) |
| PACSS classification |
| Grade 0 |
2 (3.2) |
| Grade 1 |
4 (6.5) |
| Grade 2 |
8 (12.9) |
| Grade 3 |
14 (22.6) |
| Grade 4 |
34 (54.8) |
| Lesion length (mm) |
150 [60–260] |
| Chronic total occlusion |
20 (32.3) |
| Reference vessel diameter (mm) |
4.34 [3.74–5.27] |
| Minimal lumen diameter (mm) |
0.61 [0–1.23] |
| Below the knee run-off |
1 [1–2] |
Continuous data are presented as mean [interquartile range]. Categorical data are presented as n (%). †Defined as ejection fraction <50%. EVT, endovascular therapy; LDL, low-density lipoprotein; PACSS, Peripheral Artery Calcium Scoring System; TASC, TransAtlantic Inter-Society Consensus.
Procedure Characteristics
The RA burr sizes and OAS crown sizes are shown in Table 2. Two RA burr sizes were used in 11 patients. The balloon size for predilatation was 6 (5.5–6) mm, and the DCB size was 6 (6–6.25) mm. The rate of standalone DCB treatment was 93.5%, and 4 patients required bailout stenting (1 due to vessel perforation). The procedural success rate was 100%.
Table 2.
Procedure Characteristics
| Variable |
n=62 |
| Approach site, ipsilateral |
52 (83.9) |
| Rotational atherectomy |
| SC1.6 |
5 (11.8) |
| SC1.85 |
9 (15.3) |
| XC2.1/3.0 |
5 (11.8) |
| XC2.4/3.4 |
40 (67.8) |
| Use of 2 burr size |
11 (17.7) |
| Orbital atherectomy |
| 1.5 |
2 (14.3) |
| 2.0 |
12 (85.7) |
| Debulking time (min) |
3.7 [2.5–5.3] |
| Use rate of filter system |
26 (41.9) |
| Use rate of filter system+OptimoTM |
11 (17.7) |
| Predilatation balloon size (mm) |
6 [5.5–6] |
| Predilatation balloon pressure (atm) |
12 [7.3–12] |
| Use rate of drug-coated balloon |
58 (93.5) |
| DCB size (mm) |
6 [6–6.25] |
| DCB pressure (atm) |
6 [6–8] |
| Provisional stenting rate |
4 (6.5) |
| No. BTK run-off |
1 [1–2] |
| Technical success |
62 (100.0) |
| Procedural success |
62 (100.0) |
Continuous data are presented as mean [interquartile range]. Categorical data are presented as n (%). BTK, below the knee; DCB, drug-coated balloon.
Procedure Outcomes
The MLA increased from 2.0 (1.23–3.58) mm2
to 8.1 (6.4–11.8) mm2
after atherectomy (P<0.001) and to 17.8 (13.8–20.3) mm2
after angioplasty (P<0.001), and the %DS improved from 86.8% (82.7–100%) to 48.4% (36.9–60.1%) after atherectomy (P<0.001) and to 25.5% (17.3–34.4%) after angioplasty (P<0.001; Figure 2). The comparison of the symmetric index between the 2 distinct types of calcification and the 2 different atherectomy devices was analyzed using the Wilcoxon test, resulting in P values of 0.025 and 0.26, respectively. This finding indicates that, in comparison with superficial calcification, nodular calcification produced a significantly higher symmetric index when utilizing the atherectomy device. Safety evaluations included distal embolism in 11.3% of patients and residual stenosis/thrombus and vessel perforation requiring bailout stenting in 6.5% of patients (Table 3). Patients who underwent RA experienced distal embolization (8.3%) and bailout stenting (8.4%), while those who underwent OAS experienced distal embolization (21.4%) and bailout stenting (0%).
Table 3.
Peri- and Post-Operative Outcomes of the 62 Patients in the OAS Group and the RA Group
| |
Overall
(n=62) |
OAS
(n=14) |
RA
(n=48) |
| Complication |
| Vessel perforation |
1 (1.6) |
0 (0.0) |
1 (2.1) |
| Severe dissection with contrast delay |
0 (0.0) |
0 (0.0) |
0 (0.0) |
| Bail-out stenting |
3 (4.8) |
0 (0.0) |
3 (6.3) |
| Distal embolization |
7 (11.3) |
3 (21.4) |
4 (8.3) |
| Additional procedures due to distal embolization |
| Aspiration or embolectomy |
3 (4.8) |
1 (7.1) |
2 (4.2) |
| Aspiration+angioplasty |
4 (6.5) |
2 (14.3) |
2 (4.2) |
| Intra-arterial thrombolysis |
0 (0.0) |
0 (0.0) |
0 (0.0) |
| Post-operative 30-day event |
| Death |
0 (0.0) |
0 (0.0) |
0 (0.0) |
| Major amputation |
0 (0.0) |
0 (0.0) |
0 (0.0) |
| Major re-intervention |
0 (0.0) |
0 (0.0) |
0 (0.0) |
| Post procedural ABI |
0.97 [0.85–1.05] |
1 [0.92–1.05] |
0.95 [0.85–1.07] |
Continuous data are presented as mean [interquartile range]. Categorical data are presented as n (%). ABI, ankle-brachial index; OAS, orbital atherectomy system; RA, rotational atherectomy.
Details of the additional treatment for distal embolization after the atherectomy procedure are also included. All patients were performed by aspiration. However, 2 patients in the RA group and 2 patients in the OAS group required additional plain angioplasty, because flow was not fully recovered following aspiration. In addition, the calcification volume decreased from 1.88 mL to 1.75 mL after atherectomy, and the overall volume was reduced by 7.8% (P<0.001), although this was evaluated in only 36 patients; RA resulted in a decrease of 8.04%, and OAS resulted in a decrease of 7.38%. Representative images of patients undergoing RA (Figure 3) and OAS (Figure 4) are shown as follows: calcification volume on preoperative and postoperative CT scans and DA (Figures 3a–d,4a–d), MLA on preoperative and postoperative IVUS (Figures 3e,4e), and %DS on preoperative and postoperative angiography (Figures 3f,4f). Regarding the relationship between the type of lesion calcification (superficial or deep, nodular calcification) and distal embolism, 7 patients had nodular calcification. Regarding distal embolism, we performed a logistic regression analysis considering patient, anatomical, and procedural factors. However, no statistically significant differences were observed in any of these factors. This lack of significant findings is likely attributable to the low number of events in our dataset. Therefore, comparing clinical characteristics with or without embolization, the 2 groups are significantly different in the history of CLTI, presence of popliteal lesions and nodular calcification (Table 4). Therefore, distal embolism tends to be reduced when proximal protection and a filter system are used in combination.
Table 4.
Comparison of Clinical Characteristics With or Without Distal Embolization
| |
Distal embolization
(n=7) |
Non-distal embolization
(n=55) |
P value |
| Sex, male |
5 (71.4) |
39 (70.9) |
0.98 |
| Age |
75 (70–87) |
76 (70–82) |
0.73 |
| Body mass index (BMI) |
22.8 (20.7–28.4) |
22.6 (20.4–26.1) |
0.66 |
| Current smoker |
0 (0.0) |
13 (23.6) |
0.06 |
| Hypertension |
5 (71.4) |
50 (90.9) |
0.18 |
| Dislipidemia |
4 (57.1) |
45 (81.8) |
0.16 |
| Diabetes |
4 (57.1) |
40 (72.7) |
0.41 |
| Hemodialysis |
4 (57.1) |
15 (27.3) |
0.12 |
| Coronary artery disease |
4 (57.1) |
34 (61.8) |
0.81 |
| History of CLTI |
5 (71.4) |
15 (27.3) |
0.02 |
| CTO |
2 (28.6) |
18 (32.7) |
0.82 |
| Lesion length (mm) |
80 (52.5–155) |
150 (60–260) |
0.22 |
| Proximal RVD (mm) |
5.39 (4.52–5.63) |
5.28 (4.32–5.77) |
0.67 |
| Distal RVD (mm) |
4.74 (3.75–5.9) |
4.28 (3.72–5.19) |
0.35 |
| Popliteal lesion |
7 (100) |
39 (70.9) |
0.03 |
| Run-off ≤1 |
5 (71.4) |
26 (47.3) |
0.22 |
| TASC D |
0 (0.0) |
2 (3.64) |
0.49 |
| TASC C/D |
3 (42.9) |
32 (58.2) |
0.44 |
| PACSS 4 |
6 (85.7) |
28 (50.9) |
0.07 |
| PACSS 3/4 |
3 (42.9) |
32 (58.2) |
0.44 |
| Use of filter system |
2 (28.6) |
35 (63.6) |
0.08 |
| Use of proximal protection |
0 (0.0) |
11 (20.0) |
0.09 |
| Nodular calcification |
7 (100) |
34 (61.8) |
0.01 |
| Use of blazes up |
3 (42.9) |
39 (70.9) |
0.15 |
| Additional SC |
2 (28.6) |
9 (16.4) |
0.45 |
| Pre MLA (mm2) |
1.8 (1–2) |
2 (1.3–3.83) |
0.20 |
| Pre MLD (mm) |
1.1 (0.9–1.2) |
1.25 (1.1–1.69) |
0.19 |
| Pre calcium arc (°) |
290 (143–360) |
186.5 (139.5–345) |
0.39 |
| Pre LSI |
0.5 (0.32–0.78) |
0.45 (0.27–0.74) |
0.99 |
Continuous data are presented as mean (interquartile range). Categorical data are presented as n (%). CLTI, chronic limb-threatening ischemia; CTO, chronic total occlusion; LSI, lumen symmetric index; MLA, minimum lumen area; MLD, minimum lumen diameter; PACSS, Peripheral Artery Calcium Scoring System; RVD, reference vessel diameter; SC, SC1.6 or SC1.85; TASC, TransAtlantic Inter-Society Consensus.
Discussion
The present study revealed that atherectomy reduced the QVA values, increased the MLD and MLA, and reduced the calcification volume on CT scans. In addition, distal embolization, a safety issue, was observed in 7 of the 62 patients, all of whom had nodular calcifications.
Severely calcified lesions are common in patients undergoing EVT. According to the morphological classification of atherosclerosis,10,11 significant lesions in patients with PAD generally present as calcified rather than atherosclerotic lesions.11 EVT for FP lesions with such severe calcification results in poor clinical outcomes. Fujihara et al. reported that securing the lumen is more difficult in calcified lesions than in non-calcified lesions, calcification of ≥180° is an independent factor for securing the lumen, and the restenosis rate is significantly higher.10 According to Taneva et al., DCB is superior to conventional balloon dilatation in the treatment of atherosclerotic FP artery disease, which remains a challenge; however, balloon dilatation is insufficient in calcified lesions, and calcium prevents drug absorption.5 Calcium can also lead to external compression, poor expansion, and stent fracture over time, making stent placement challenging. Jetstream atherectomy is designed to provide more uniform and successful plaque removal while minimizing the risk of elastic vessel recoil, dissection, and stent placement.5 Shammas et al. reported a similar procedure for orbital atherectomy.12 As in previous reports, the changes in MLA were similarly increased in terms of luminal gain; QVA results revealed that the %DS decreased to 49% after atherectomy and to 26% after DCB, and calcification amounts decreased by approximately 7.8% overall on CT. This may have led to a low rate of bailout stenting. However, the rate of distal embolization was significantly higher than that reported in previous studies.2,5 In Japan, a substantial number of patients have comorbidities such as end-stage renal disease and diabetes. In addition, patients, especially those undergoing dialysis, occasionally have lesions with nodular calcification and a high rate of distal embolization. Nodular calcification may occur during the use of an atherectomy catheter, which may detach from the intima, either in whole or in part, and this is a risk factor for distal embolization. In addition, despite the use of a filter to prevent distal embolization, 3 patients experienced distal embolization in this study. This may be because the structure of the Filtrap (Nipro Corporation, Tokyo, Japan) used in the filter has 100 μm membrane holes, and particle debris smaller than this size is not captured by the filter and can disperse to the periphery. As methods for preventing distal embolization, we recommend the following tips: identification of the cutting area and minimizing the cutting distance through IVUS evaluation, and placement of a filter device.
Study Limitations
First, this was a single-center, single-arm, retrospective study. Second, only included Japanese patients were included in the study, and patient backgrounds, such as the proportion of patients on hemodialysis, were different to those in other countries; therefore, the results cannot be fully generalized. Third, only 30-day data were available; therefore, mid- to long-term results, such as primary and secondary patency rates, were not available. Fourth, angiography and IVUS analyses were performed in-house, and there was no specialized facility, such as a core laboratory; therefore, measurement errors were possible. Last, we note the potential for variations between observers and acknowledged that we cannot completely eliminate bias.
Conclusions
Use of atherectomy systems significantly increases the lumen dimensions in severely calcified FP lesions by removing superficial calcium without increasing the risk of major complications. However, a substantial incidence of distal embolisms is unavoidable. Regarding use of a procedural device for reducing the risk of distal embolism, we have described the need for further procedural improvements in embolization prevention, such as implementing proximal protection and enhancing filter systems.
Acknowledgments
The authors thank the medical staff of the cardiac catheterization laboratories at their respective centers. Written informed consent was obtained from the patients for publication of this article and any accompanying images.
Sources of Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Disclosures
H.M. is a member of Circulation Reports’ Editorial Team. The other authors declare that there are no conflicts of interest.
Data Availability
The deidentified participant data will not be shared.
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