In clinical practice, paclitaxel is used in DEB as an effective antiproliferative agent. The drug is highly lipophilic, with rapid penetration into the tissue. The method of paclitaxel binding to the balloon catheter surface is probably the single most significant factor influencing the PEB efficacy. Originally, as described by Scheller et al., paclitaxel was bound via a hydrophilic contrast agent iopromide increasing its solubility and vascular wall penetration . It has been established that 3 µg/mm2 is the optimum drug concentration , which is the case also in both compared PEBs.
Multiple studies with follow-up times of 9 to 12 months demonstrated the efficacy of iopromide-coated PEB treatment for BMS-ISR in comparison with POBA or paclitaxel-eluting stents (PES); however, the comparison of PEB with the 2nd generation DES with everolimus (everolimus-eluting stents; EES) still remains unclear. Moreover, the long-term results of these studies are now also available.
In the long-term follow-up (5.4+/-1.2 years) of Paccocath I and II studies, the PEB group confirmed the sustained significant reduction of MACE (p = 0.009) compared to POBA, which was largely driven by the TVR incidence reduction from 38.9–9.3% (p = 0.004) [8, 9].
In the PEPCAD II study, despite the trends toward reduced 12-month incidences of binary restenosis (p = 0.06) and MACE (p = 0.08) , at 3-year follow-up, the differences in incidences of MACE (p = 0.14) and TVR (p = 0.10) between PEB and PES groups did not reach statistical significance .
Contrary to different 12-month angiographic results between the TIS and RIBS V studies comparing the PEB and EES [2, 12] in the long-term clinical follow-up, the only significant difference was a lower incidence of target lesion revascularisation in the EES group of the RIBS V study (p = 0.04). The overall incidence of 3-year MACE did not differ between the groups in both studies (p = 0.230 and p = 0.64, respectively) [13, 14].
Many other PEBs with different coating are currently used in clinical practice, including the DIOR II (shellac-coated; Eurocor, Bonn, Germany), the IN.PACT Falcon (urea-coated; Medtronic, Minneapolis, USA), the Pantera Lux (butyryl-tri-hexyl citrate [BTHC]-coated; Biotronik, Berlin, Germany), etc. Nevertheless, among several registries, the most favourable results were achieved with the use of iopromide-coated PEB.
In a subanalysis of the SCAAR registry, iopromide-coated PEB (paclitaxel 3 µg/mm2) was used for treating ISR lesions. Compared to uncoated PEB (paclitaxel 2 µg/mm2), iopromide-coated PEB was associated with a lower risk of binary restenosis (adjusted HR: 0.48; 95%CI: 0.23–0.98 .
Benezet et al. found that patients with BMS or DES-ISR treated with iopromide-coated PEB displayed a significantly lower TLR rate at 36 months (p = 0.03) compared to shellac-coated PEB .
In contrast, in the Düsseldorf DCB registry, patients treated for ISR with BTHC-coated PEB had significantly longer event-free survival rates (p = 0.405) than those treated with the iopromide-coated PEB .
In a non-randomised study, Nijhoff et al. compared the efficacy of urea-coated and shellac-coated PEB in patients with BMS or DES-ISR. The urea-coated PEB group showed significantly lower 6-month LLL (p = 0.014), a higher FFR value distally (p = 0.029), and a reduced volume percentage of neointimal hyperplasia (p = 0.006). The incidence of repeated binary restenosis was not significantly different between groups (p = 0.16) and a trend was observed towards lower TLR (p = 0.057) in the urea-coated PEB group .
Our results confirm that iopromide coating influenced the efficacy of PEB in ISR treatment. We previously demonstrated that patients with BMS-ISR showed significantly higher 12-month LLL (p < 0.0001), incidence of repeated binary restenosis (p = 0.012), 12-month MACE (p = 0.003) and TVR (p = 0.009) rates following treatment with seal-wing PEB compared to iopromide-coated PEB .
The difference in the overall MACE incidence was predominantly caused by the significantly higher incidence of TVR in the seal-wing PEB group due to a higher rate of repeated binary restenosis. No significant differences were found between the groups where CV mortality, MI, definite ST or the second MACE are concerned. These differences in the clinical outcomes (MACE and TVR) occurred mainly during the first year, however they also persisted after 3 years of follow-up.The use of the seal-wing PEB for BMS-ISR treatment was associated with a significantly higher risk of MACE (including TVR), even after the adjustment for significantly different baseline variables.
Our study has several limitations. In particular, it was a non-randomized study comparing patients who underwent one type of treatment (seal-wing PEB) with patients from the control arm of the previous TIS study.
Nevertheless, the baseline parameters of both patient cohorts did not differ with respect to main baseline parameters and hence, it is unlikely that the selection bias would have played a major role. Similarly, the further clinical follow-up and medical therapy, including duration of dual antiplatelet treatment, were also the same.