Author + information
- Marianne Brodmann, MD,
- Martin Werner, MD,
- Todd J. Brinton, MD,
- Uday Illindala, MS,
- Alexandra Lansky, MD,
- Michael R. Jaff, DO, RPVI and
- Andrew Holden, MD∗ ()
- ↵∗Vascular Offices, Level 4/Building 32, Auckland City Hospital, 2 Park Road, Grafton, Auckland 1023, New Zealand
Percutaneous transluminal angioplasty of calcified peripheral artery lesions often results in suboptimal vessel expansion. Angioplasty of calcified lesions is often associated with acute loss of patency due to residual stenosis or dissection, often requiring stenting (1,2). A high rate of chronic failure due to restenosis is also seen, resulting in target-lesion revascularization. Plaque modifying devices, including atherectomy, remove atheroma and have shown improved lumen diameter and reduced bailout stenting. However, vascular complications and significantly higher rates of procedural distal embolization requiring adjunctive tools still persist along with suboptimal patency (3). Lithotripsy is a well-characterized treatment adopted for calcified renal calculi, in which calcifications are fragmented by high-power acoustic shockwaves. Lithoplasty is a technology based on lithotripsy, in which multiple emitters mounted on a traditional balloon catheter provide circumferential pulsatile energy to disrupt calcified plaque and improve acute gain while minimizing vessel injury. The goal of this study was to demonstrate the safety and performance of the Peripheral Lithoplasty System (Shockwave Medical, Fremont, California) for treatment of calcified, stenotic peripheral arteries.
We prospectively enrolled 35 patients with calcified, stenotic, de novo femoropopliteal arterial lesions. The balloon, sized 1:1 to the reference vessel diameter, was inflated to 4 atm, and 30 pulses were delivered followed by further dilation to nominal pressures. The procedure was repeated providing a minimum of 60 pulses in the target lesion per vessel segment with interval deflation to allow for distal perfusion. Investigators were initially trained using a bench model, and all cases had clinical specialist support. Key inclusion criteria included moderate or severe calcification, reference vessel diameter 3.5 mm to 7.0 mm, stenosis ≥70%, lesion length ≤150 mm and 1 patent runoff vessel to the foot. Key exclusion criteria included Rutherford category 5 or 6, untreated significant inflow disease, and significant renal disease or dialysis. Procedural angiograms along with duplex ultrasounds at discharge, 30 days, and 6 months were analyzed by a core laboratory. Calcification was identified by the angiographic core laboratory as readily apparent densities at the site of stenosis extending at least one-half the lesion length and defined as moderate or severe on the basis of single side or bilateral involvement, respectively.
The primary performance endpoint was procedural success defined as post-treatment residual diameter stenosis of <50% with or without adjunctive percutaneous angioplasty per the core laboratory. Loss of vessel patency was defined as ≥50% restenosis by duplex ultrasound core laboratory review. Major adverse events were assessed at 30 days and 6 months, and defined as emergency surgical revascularization, target-limb amputation, thrombus or distal emboli requiring treatment, or perforation/flow-limiting dissections requiring intervention including stenting. Functional outcomes including improvement in ankle brachial index and Rutherford category were assessed through 6 months.
Initial stenosis was 76.3% with an average lesion length of 61.5 mm. Calcium burden was significant with severe calcification reported in 64.1% of patients, and an average calcified length of 80.3 mm. The balloon was delivered successfully in all patients and required minimal use of pre- and post-dilation (8.6% and 14.3%). Procedural success occurred in all patients, and the final residual stenosis was 23.4% with an acute gain of 2.9 mm. The average number of pulses was 104, mean balloon pressure 7.1 mm Hg, and average treatment time of 11 min per patient. There were no vascular complications at index procedure adjudicated by the core laboratory, and no stents were implanted. Distal embolic filters were used at the discretion of the investigator in a total of 6 cases, and thrombus was present in 1 filter. Vessel patency at 30 days and 6 months was 100% and 82.1%, respectively with no target lesion revascularizations within 6 months (Figure 1). There were no major adverse events reported through 6 months. The ankle brachial index and Rutherford category were improved from pre-procedure examination and sustained through 6 months.
The DISRUPT PAD I (Safety and Performance Study of the Shockwave Lithoplasty System) was the first study to investigate lithotripsy on a traditional balloon catheter to treat calcified, stenotic lesions. The system successfully treated calcified femoropopliteal lesions, traditionally challenging and time consuming to treat, with limited adjunctive balloon use and no implants. The results show a dramatic reduction in stenosis severity with high acute gain and minimal vessel injury. There were no major adverse events or revascularizations after the index procedure, and vessel patency was durable out to 6 months. Importantly, the system appeared to change vessel wall compliance in this study as evidenced by balloon expansion during sonic pulsing while maintaining the same low pressure. This result suggests disruption of both superficial and deep calcium in the vessel wall.
Finally, the study suggests that lithoplasty for the treatment of calcified femoropopliteal arteries is safe and effective. These positive results indicate lithoplasty may play an important role in the management of calcified peripheral arterial disease. Further evaluation and procedural optimization is warranted.
Please note: This study was funded by Shockwave Medical, Inc. Dr. Brinton is a cofounder of Shockwave Medical, Inc. Mr. Illindala is an employee of Shockwave Medical, Inc. Dr. Jaff has served as a noncompensated advisor for Abbott Vascular, Boston Scientific, Cordis, and Medtronic; is an equity shareholder (<1% of corporate value) of PQ Bypass; and is a compensated board member of VIVA Physicians (501c3 not-for-profit education and research organization). All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2017 American College of Cardiology Foundation