Treatment of the bifurcations is often challenging procedure requiring operator experience and excessive contrast and X-ray time. Though provisional stenting is preferred strategy not rarely two stents strategy is needed. Standard stents are designed to treat straight segments and not bifurcations where excessive strut deformation is needed. Dedicated stents can offer better behaviour in the bifurcation side and are divided in two major categories:  those that treat the main branch (MBs) and those that protect the side branch (SBs) (Fig.1). Bioss LIM (Balton, Poland) is MBs Sirolimus eluting stent that respects the fractal geometry of the bifurcation with larger in diameter proximal part than the distal one. Two connecting struts join both proximal and distal parts that are mounted on specially designed tapered balloon.  Advantage of this stent is very easy access to the side branch (SB). Available at that time dedicated stents that scaffold the side branch were Tryton (Tryton Medical, Durham, UK) bare metal stent and Biomime Branch (Meril, India) Sirolimus eluting stent. Distinguish characteristic of both stents is scaffolding of the side branch, presence of transition zone at the level of the carina and proximal main branch part being just anchoring the system to the vessel. Both stents require finalizing of the procedure by implantation on the main vessel of standard drug eluting stent. We decide to adopt both type of dedicated stent for through bifurcations as first to implant the dedicated SBs (Tryton or BioMime Branch) and after that to fix the main branch with MBs Bioss Lim. By this technique we tried to have less metal at the carina side but to have easy access to the side branch for kissing balloon (KB).

From Jan 2020 to September 2021, we treated 24 pts with through coronary bifurcations. Mean age was 65 ± 12 y and from them 18 were males. All lesions were Medina 1.1.1. and by initial decision the strategy was to use two stents. The distributions were LM in 2 (8%); 14 (58%) LAD/D1, 8 (33%) LCx/OM and 2 (8%) PD/PL bifurcations. Mean MB diameter was 3,2 ± 0,7 mm, mean SB diameter was 2,7 ± 0,5 mm, mean MB stenosis length was 19,3 ± 1,3 mm and the length for SB stenosis was 5,1 ± 0,7 mm. Mean stenosis for the MB was 82 ± 13,5%. Stable angina was seen in 18 (75%) patients and acute coronary syndrome (ACS) in the rest 6 (25%). In 18 (75%) patients IVUS and in 6 (25%) OCT was used as adjunctive imaging method at least at the end of the procedure and in 4 (17%) patients FFR/iFR was used during and the end of the procedure. In 9 (38%) patients the SB was treated with Tryton stent with mandatory SB post-dilatation with drug coated balloon. In the remaining 15 patients (63%) the SB was treated with BioMime Branch DES. Briefly describing the procedure in all patients, the preparation of both SB and MB with KB pre-dilatation with non-compliant balloons at 1:1 ratio was done before the SBs stent placement. Once the SBs was positioned controlling in two angiographic projections a POT with 0,5 mm larger balloon was performed. Keeping the balloon within the proximal part of the SBs, the wire from SB was repositioned in the MB. Then a second dedicated DES - Bioss Lim was positioned in the main vessel. The precise position was confirmed using stent enhancement (Fig.2.). After second stent deployment a second POT was performed in all cases. After that rewiring of the SB was done and the procedure was completed by second KB and re-POT dilatation.  Variables as wires, balloons and contrast use as also procedure and X-ray time as also procedure and device success were calculated.  Clinical follow-up was done at 1st and 6th months and angiographic at one year.

Radial approach was used in all patients. Mean procedure time was 125,8±18,7 min and the mean X-ray time was 25,8±8,0 min. Mean amount of contrast dial was 108,6±25,3 ml. Mean number of coronary wires was 2,3±0,7; mean number of all type balloons was 5,3 ±1,3. Procedure success was achieved in all patients and device success (Fig. 5) for both stents was also 100 percent. We were able to position all side branch dedicated stents at first attempt. Repositioning of the wire from SB toward the MB didn't present any difficulties. All second dedicated stents Bioss Lim without the need of further predilatation passed and were implanted with success. To mention the better visualization of the BioMime Branch stent respect the Tryton stent.  Also to mention the relatively higher cost of the procedure performed with Tryton stent as the balloon for the SB during the final kissing was drug coated one with the idea to reduce the rate of SB restenosis as the Tryton stent is bare metal. Should be emphasized that the recrossing with wire and subsequently with balloon through the struts of Bioss stent toward the already scaffold SB was relatively easy and in all cases with success. In all 4 patients where at the end we performed FFR/iFR measurement the MB and SB FFR where largely above 0,90. In all patients where we performed final IVUS/OCT assessment the probe easily passed in both MB and SB and the carina was well opened as also the both stents were well apposed to the vessel wall. All patients at clinical follow-up were free of symptoms. At one year angiographic control there were one patient with instent restenosis on both MBs LAD (Bioss) and SBs D1 (Tryton) stents that were successfully treated with DCB.

The bifurcation dedicated stents in some favor anatomic situation are adjunctive devices that can facilitate the success of the procedure. Both dedicated stents used in our work either MBs one Bioss Lim either SBs scaffolding stents BioMime Branch or Tryton demonstrate easy placement particularly when all steps of bifurcation treatment procedure are respected. Bioss Lim DES due to its design has the advantage to permit wide access toward the SB, particularly when the SB is already stented. The dedicated bifurcation stents Tryton in combination with final DCB balloon or BioMime Branch benefit the presence of drug Sirolimus and by this can be used even in diabetic patients and probably at low restenosis rate. The combination of dedicated side branch stent especially if it is drug eluting and there after placing a dedicated MB stent has the rationality to reduce the amount of metal at the carina site and to permit SB access during the procedure. This combination according to our experience is absolutely feasible and without increasing the procedural risk of complication as also without increasing the procedural variables as time and contrast amount.