At the International Symposium on Endovascular Therapeutics (SITE; 24–27 June, Barcelona, Spain) Gustavo S Oderich, Mayo Clinic, Rochester, USA, said that there are no definitive studies supporting routine use of embolic protection devices in superficial femoral artery interventions. However, he stated that these devices prevent embolisation during complex procedures.
“Embolisation during peripheral intervention is a problem we all face. We can have very good results and sometimes at the end of the procedure we are surprised with embolisation to the tibial vessels,” said Oderich, who is professor of Surgery, director of Endovascular Therapy, Division of Vascular and Endovascular Surgery. “The rate of embolisation varies in the literature (<1–12%) depending on the extent of the procedure, type of the technology and indication for which the procedure was performed. Embolisation can often be remediated with relatively simple techniques of aspiration but in some cases it requires bail out maneuverers such as lytics, thrombectomy and even conversion to open repair, and also can lead to an escalating level of care with intensive care, longer hospital stay and potential risk of limb loss.”
Despite significant advances in lower extremity technology, Oderich noted that there are limited data on the use of embolic protection device for superficial femoral artery intervention.
In a prospective study of 48 patients by Karnabatidis et al (J Endovasc Ther 2006) microscopic debris were found in 94% of embolic protection device baskets. Another prospective study of 29 patients treated by angioplasty/stenting evaluating the FilterWire EZ device (Boston Scientific) also demonstrated macroscopic debris was retrieved in all baskets. In the DEEP EMBOLI trial using Excimer Laser Ablation atherectomy in peripheral interventions (Shammas et al. J Endovasc Ther 2009), 68% of patients had microscopic debris. However, only one patient (5%) out of the 20 patients treated for chronic total occlusions with the Spider Rx EPD (Medtronic/Covidien) suffered embolisation to the tibial vessels.
“This issue is controversial because the filter adds to the procedural cost. In addition, it has an unproven benefit as although debris is found, embolisation to the lower vessel is infrequent. Also, there are potential risks with embolic protection device such as trauma, dissection, spasm, entrapment of filter basket and difficulty with filter retrieval,” Oderich said.
Explaining the two-wire technique, he commented the lesion needs to be crossed with a 6–7F sheath for support. He added, “You can use a variety of catheters of your choice. I tend to use a straight Glidewire to cross this lesion. Once I confirm I am in the true lumen, I tend to use the Spider RX 320cm in length. A good trick is to introduce the filter through the 0.035-inch catheter. Also, my preference is to use also a buddy wire as it helps to retrieve the filter basket and provides more support for 0.035 interventions. At the end of procedure, with the basket removed you can evaluate the nature of the debris.”
Oderich’s group performed a retrospective review (Mendes et al. J Vasc Surg 2013) looking at data collected between 2002 and 2012 for 536 patients and 856 elective superficial femoral artery interventions. The device used was the Spider RX embolic protection device. The filters were more used for occlusions (30 patients without EPD and 64 with EPD, p<0.001) and for longer lesions (85±76mm vs. 109±94, p=0.02). The investigators observed 35 embolic events (4%) on completion angiography. Sixty eight per cent of the baskets had macroscopic debris, and 2% patients with embolic protection had an embolisation, likely due to platelet aggregation next to the filter, and both were immediately resolved with local tPA.
There were 33 patients (4%) with emboli without embolic protection. Seventy six per cent required an intraprocedural manoeuvre, and 21% had continued catheter-directed thrombolysis. Overall 92% had angiographic resolution or improvement. One patient (3%) had an unanticipated below-the-knee amputation.
When looking at outcomes between embolism and no embolism patients, the research team saw that mortality was not statistically significant (p=0.11); however, there were higher rates of major amputation (p=0.02) and need for reintervention (p<0.001) in the embolic group, with chronic total occlusion being the only predictor.
In conclusion, Oderich said, there are no definitive studies supporting routine use of embolic protection devices and added that the use of these devices should be considered in patients with long-segment chronic total occlusion, primary atherectomy, acute or subacute symptoms and single vessel run-off.
“Attention to technical detail is key to avoiding arterial trauma or embolic protection device entrapment in stents. The two-wire technique helps with guidewire support and embolic protection device retrieval,” he said.