Safety and Efficacy of Lithoplasty in Treating Severely Calcified Iliac Arterial Disease: A Single Center Experience

VASCULAR DISEASE MANAGEMENT 2019;16(6):E76-E78

Abstract

Calcified iliac arteries may pose a challenge to treat using endovascular techniques. Shockwave lithoplasty was recently approved to treat severe calcified peripheral arterial disease. We present 7 patients with iliac artery disease treated with Shockwave lithoplasty prior to definitive treatment with stenting. High acute procedural success was noted with no complications. Mean stent diameter post lithoplasty after Shockwave was similar to expected stent diameter per manufacturer’s label. We conclude that Shockwave lithoplasty before stenting of calcified iliac arteries can lead to excellent stent expansion and high acute procedural success.

Severe calcified iliac arteries are a challenge to treat using endovascular techniques, as they often can be difficult to dilate, which may result in stent under-expansion, thrombosis, and restenosis.¹ In general, atherectomy use is contraindicated in the iliac arteries. Even when used to treat heavily calcified iliac arteries, atherectomy can only modify superficial or atherosclerotic calcium and may not reach medial or deeper calcinosis.² 

Lithoplasty (Shockwave Medical) provides circumferential pulsatile energy to disrupt calcified plaque, superficial or deep, which allows optimal vessel expansion at lower barometric pressure while reducing vessel injury.^3,4 The Shockwave device has been tested in coronary and femoropopliteal calcified arteries with overall excellent results.^3-5 In addition to improving vessel compliance, it is anticipated that calcium disruption will allow better anti-proliferative drug penetration inside the vessel wall. This concept is being evaluated as part of the Disrupt PAD III trial (ClinicalTrials.gov Identifier: NCT02923193).

There are currently minimal data on the use of lithotripsy in iliac arteries. In this small series, we evaluate the use of lithoplasty as an adjunctive treatment to stenting in severely calcified iliac arteries to determine its impact on stent expansion and acute procedural outcome. 

Methods

In this retrospective analysis from a single center, we report a series of 7 cases of severely calcified iliac arteries treated with the Shockwave lithoplasty balloon prior to iliac artery stenting by one operator (NWS) at a single institution. These patients have been enrolled in the ongoing Shockwave registry at our institution. The registry has been approved by the Ethics committee at Trinity UnityPoint Health System. Demographic, clinical, angiographic, procedural, and in-hospital outcome data were collected on all patients. 

The primary effectiveness endpoint was acute procedural success (≤ 30% residual) with no complications. The primary safety endpoint was freedom from major adverse events, including major dissection (NHLBI C or higher), perforation, distal embolization, mortality, or amputation. A secondary angiographic endpoint included the mean stent diameter post deployment versus the expected stent diameter per manufacturer’s label, analyzed by the Midwest Cardiovascular Research Foundation quantitative vascular lab. 

Secondary endpoints included the following: 30-day adverse events, the need for target lesion revascularization, target-limb amputation, and vascular-related death. Clinical outcomes at 1 month were assessed with change in Rutherford Becker (RB) category. Ankle brachial index was not routinely performed at 1 month, and so these data were not available for analysis. 

Results 

Seven patients (mean age 67.3 ± 6.7 years, 5 males) were included in the study. A total of 3 left iliac arteries and 4 right iliac arteries were treated. All lesions were de novo. Initial stenosis was 95 ± 6.45%, and 57% of lesions were chronic total occlusions. Lesion length was 65.71 ± 9.75 mm, and vessel diameter was 6.35 ± 0.99 mm. The calcium burden was significant, with severe calcification (bilateral calcium more than 3) noted in 85.8% of patients, and moderate calcium in 14.2% of patients, as judged by the operator. 

The Shockwave balloon was delivered successfully in all patients. The mean Shockwave balloon diameter was 6.5 ± 0.87 mm, and the mean number of pulses delivered was 72.14 ± 23.07. There were 2 cases treated with atherectomy (1 Jetstream [Boston Scientific]) and 1 Orbital atherectomy (CSI) prior to Shockwave. There were 3 dissections (12.5%), all NHLBI type C, that followed the Shockwave treatment. An embolic filter was used in 1 case, and stenting was performed on 100% of lesions. Residual stenosis was estimated to be 0% in all cases. There were no perforations, distal embolization, or amputation. Procedural success was 100%. Table 1 shows patient-specific details. 

Angiographic core laboratory assessment showed full stent expansion across its entire length with no focal area of narrowing.  When compared with the theoretical diameter of the stent, there was no difference between post deployment stent diameter and expected stent diameter (mean actual post deployment stent diameter was 7.46 mm versus mean expected stent diameter of 8.0 mm, P = 0.31 using Wilcoxon Rank Sum test for comparison). 

No adverse events were noted at 1 month, and there were no vascular-related complications. Mean RB on 1-month follow-up also improved significantly (mean RB at baseline, 3.3 ± 0.8 vs mean RB at 1 month, 1.7 ± 1.5).  

Discussion

In this small series of  7 patients, Shockwave lithoplasty to the iliac arteries showed excellent procedural success and no complications. Full stent expansion was noted, and this result was comparable to the expected stent diameter per the manufacturer’s specifications. 

Calcified iliac arteries are quite challenging to treat and often result in stent under-expansion, which may lead to loss of patency. The use of lithoplasty seems to yield full stent expansion in our small series. Lithoplasty in calcified iliac arteries has been demonstrated during trans-aortic valve procedures in which access is routinely obtained with large bore arterial sheaths.  More data will become available on lithoplasty in iliac arteries from the ongoing Shockwave multicenter registry. The ultimate test for lithoplasty in iliac arteries is a randomized trial that compares the use of lithoplasty versus balloon angioplasty prior to final treatment with stenting.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Shammas receives educational and research grants from Intact Vascular, Phillips, Boston Scientific, VentureMed Group and Bard. John Shammas, Dr Radaidah, and Gail A Shammas report no conflicts of interest regarding the content herein.

Manuscript submitted March 1, 2019; accepted March 8, 2019.

Address for correspondence: Nicolas W. Shammas, MD, MS, EJD, FACC, FSCAI, FSVM, Midwest Cardiovascular Research Foundation, 1622 E. Lombard Street, Davenport, Iowa, 52803. Email: shammas@mchsi.com

REFERENCES

1. Ali Z, Di Marlo C, Maehara A, et al. DISRUPT CAD: a multicenter, prospective, single-arm study of percutaneous lithoplasty prior to stent implantation in heavily calcified coronary lesion. J Am Coll Cardiol. 2016;68 (TCT Suppl).

2. Maehara A, Mintz GS, Shimshak TM, et al. Intravascular ultrasound evaluation of JETSTREAM atherectomy removal of superficial calcium in peripheral arteries. EuroIntervention. 2015;11(1):96-103. 

3. Brodman M et al Primary outcomes and mechanism of action of intravascular lithotripsy in calcified, femoropopliteal lesions: Results of Disrupt PAD II. Catheter Cardiovasc Interv. 2019;93(2):335-342.

4. Ziad Ali, Brinton TJ, Hill JM, et al.  Optical coherence tomography characterization of coronary lithoplasty for treatment of calcified lesions: first description. 2017;10(8):897-906. 

5. Brodmann M, Werner M, Brinton TJ, et al. Safety and performance of lithoplasty for treatment of calcified peripheral artery lesions. J Am Coll Cardiol. 2017;70(7):907-912.