Endovascular atherectomy by either directional or rotational systems has developed as an alternative method since 199010,11,18,19 especially for lesions being resistant to simple POBA or stenting8,21 or for mobile vessel segments where stenting might cause early restenosis.
The evasion of plaques material and partially also the inner layers of the vessel wall allows effective lumen gain and the reduction of biologically active components, that are repsonsible for the early physiological response with restenosis initiation. The wider post atherectomy lumen also allows to postdilate with lower inflation pressure to achieve good results thus reducing further barotrauma to the vessel wall. On the other hand, all atherectomy modalities increase the risk of distal embolization22 with an eventrate up to 22% in some surveys vs. 0.9% for POBA alone23
Furthermore, the robustness of the devices with sharp cutting edges rotating at high speed for plaques demolition increases the risk of mechanical and thermal vessel injuries25, especially when the guidewire should go subintimal in long occlusions.
The novel rotational atherectomy system BYCROSS® follows a new philosophy. The low rotational speed and the dual transport system showed to be effective in preventing embolic events, which did not happen in the trial despite the complex lesion morphology with up to 450mm length. In 11 lesions, passage could be achieved without initial wire guidance.
The results from the trial have shown that the device is highly effective with a 95.12% technical success rate with lower confidence limit greater than or equal to 85% and no intraprocedural MAE`s or SAE`s. In particular, there were no device related SAE/MAE`s. The success rate from BYCROSS® is similar to those of the EASE trial with the Phoenix™ device (Philips b.v., Best, The Netherlands), also showing a success rate of 95.1% but a MAE rate 16.8% through six months vs. 2.4% in this study, noticing, that the treated lesions in the two studies are not comparable. The EASE cohort had a mean lesion length of 34 mm vs. 124.9mm and a mean stenosis of 89.5% vs. 96.4% in the ByCross study16.
The primary performance endpoint, here the passage of the occlusion by the ByCross device and post atherectomy residual stenosis (assessed using angiography) ≤ 50% to allow for angioplasty and/or stenting if required, and complete procedural success with a residual stenosis ≤ 30%, with no Serious Adverse Events (SAE) during the procedure was met at 39/41 lesions. Primary patency (stenosis ≤ 50%) at 6-month FU was observed at 34/39 lesions, i.e 87.2% while the six-month TLR and TVR were 88.0% and 86.1% for the Phoenix™ rotational atherectomy device (Royal Philips b.v., The Netherlands) for much shorter lesions. The intraprocedural embolization rate in the bycross trial was 0% independent from lesion calcification and length without any distal protection system used. In the EASE trial (16) the rate of distal embolization was 1% and in the DEFIFINITE-LE trial with the SilverHawk and TurboHawk devices (Medtronic Inc., USA) 3.8% with distal protection (19).
The performance goal with primary and secondary safety endpoints counting all postprocedural Major Adverse Events (MAE) and SAEs at 30 and 180 days follow-up, was also met independent from gender, length of the lesion and degree of stenosis as well as PACSS at a very low rate of MAE/SAE at 30 days (0%) and 6-month FU (2.4%).
Although the lesion complexity with up to 450mm length and a mean degree of stenosis of 96.4% in a patient set with more than 77% CLI (Rutherford IV and V, subset of Bonifatius Hospital) was extreme no embolization was seen in the angiographic imaging or clinically evident.
The overall stenting rate of 29.26% can be regarded as low in this setting. For the shorter lesions (mean 53.6mm) with a higher PACSS 92% of lesions (n = 23) required adjunctive treatment with ballooning and only 12% (n = 3) required additional stenting. The longer lesions (mean length 229mm) with a more mixed morphology required POBA in 94.1% (n = 16) and stent application in 52.96% (n = 9). But in the vast majority of long lesions only spot stenting was used for flow relevant dissections or focal residual stenosis.
In the study, it was noticeable, that low pressure ballooning after atherectomy was sufficient for meeting the performance goal or less than 30% residual stenosis. No drug coated or eluting devices were used although several publications have promoted this in combination with atherectomy to reduce the focal physiologic repair mechanisms25,26.
The clinical outcome after 6 months, although not an endpoint in the protocol, also showed significant improvements.
The novel ByCross system also has several advantages when compared to other devices on the market. It is not limited to the femoropopliteal segment but can also be used in aorto-iliac recanalization according to the IFU with or against the blood flow.