The results of our study demonstrated that the use of fracking technique in the treatment of calcified CFA lesions resulted in significantly better procedure efficacy and comparable safety outcomes compared to conventional balloon angioplasty without scaffolds. Our study also indicated that a larger postprocedural MLA, as estimated by IVUS, was independently associated with a lower incidence of restenosis. Notably, a postprocedural MLA of 16.0 mm2 was identified as a specific cut-off value for preventing patency loss. These findings may help guide clinical decisions and improve patient outcomes in the treatment of calcified CFA lesions.
Various treatments, such as surgical endarterectomy, scaffolds, and atherectomy devices, have been utilized to increase lumen area and reduce restenosis in CFA disease.8–11 However, balloon angioplasty has demonstrated suboptimal results with a 1-year primary patency rate of 72.4% and a bailout stenting rate of 36.9%, due to insufficient luminal gain after balloon dilatation.17 In a previous comparative study, directional atherectomy combined with DCB resulted in a higher 1-year primary patency rate (88%) than DCB angioplasty alone (68%).18 These results suggest that a plaque modification strategy to maximize lumen area can improve restenosis when treating CFA lesions. Our study found that the residual stenosis, postprocedural MLA, and plaque burden results were significantly better in the fracking group than in the balloon group, which may lead to optimal outcomes similar to those achieved with surgical endarterectomy and atherectomy device use. Furthermore, the main purpose of fracking is to modify deep calcification, similar to lithoplasty.19 A retrospective study comparing lithoplasty and atherectomy with DCB for treating calcified CFA lesions demonstrated that the 18-month cumulative TLR was identical for both (79.4% and 91.2%, P = 0.166),20 and the procedural complication rates were 3.0% and 5.7%, respectively. The present study showed that the incidence of procedural-related complications in the fracking group was not more than that in the balloon group. Although additional punctures were made while fracking was performed, hematoma was observed at the sheath insertion site rather than the fracking puncture sites. An 18-gauge needle was used to perform fracking in this study, and hemostasis of the puncture may be easily achieved with balloon dilation after fracking. Additionally, no distal embolization was documented during the fracking procedure. Superficial calcification is less susceptible to fracking than deep calcification and may have acted as a barrier to embolization.12
This study’s findings indicated that achieving a postprocedural MLA of more than 16.0 mm2 was an independent predictor of reduced restenosis risk at one year after treatment for calcified CFA lesions. A previous study demonstrated that calcified lesions and residual stenosis were independent predictors of restenosis.21 Severely calcified lesions, particularly those with a calcification arch over 180°, prevented lumen expansion during peripheral interventions.16 However, this study found that severely calcified lesions were not a relevant predictor of restenosis. Even though lesions with calcification angles exceeding 180° were more frequently observed in the fracking group than the balloon group, the fracking technique, which was utilized in addition to balloon angioplasty, effectively cracked calcification and resulted in a larger postprocedural MLA compared to conventional balloon angioplasty alone. The average MLA in the balloon group was significantly smaller than the cut-off value of 16.0 mm2 identified in this study, which may have contributed to the lower patency rate compared to the fracking group. Previously, no study has reported a specific cut-off value from the IVUS examination that could predict restenosis of CFA lesions. On the other hand, a study of femoropopliteal lesions demonstrated that a minimum stent area < 12.0 mm2 was associated with 1-year restenosis after Zilver PTX stent (Cook Co. Bloomington, IN., USA) implantation,22 and MLA < 12.7 mm2 after DCB angioplasty was shown to predict restenosis.23 Notably, the cut-off value in our study was larger than those reported in previous studies of femoropopliteal lesions, which may be explained by the larger diameter of CFA compared to femoropopliteal artery. This study excluded scaffolds and focused exclusively on balloon angioplasty, including DCB angioplasty. In contrast to scaffolds, balloon angioplasty cannot maintain long-term lumen area in the chronic phase. Therefore, an initial minimum lumen area (MLA) after revascularization may be an essential determinant of patency. Therefore, a modification strategy should be implemented alongside balloon angioplasty to achieve an MLA larger than 16.0 mm2 in calcified CFA lesions. Fracking was performed, with a mean of 2.4 ± 0.8 times (1–4 times) and an average duration of 10.1 ± 3.8 min (4–18 min). Additionally, the fracking group had a significantly shorter radiation time than the balloon group. Fracking is a minimally invasive procedure that involves using an 18-gauge needle in addition to conventional balloon angioplasty. Therefore, this technique is cost-effective and has been shown to provide significant clinical benefits for patients with calcified CFA lesions undergoing peripheral intervention.
The current study had some limitations. First, the retrospective, nonrandomized, single-center, and observational design of the study might have led to case selection bias and nonrandom assignment. The small sample size may have affected the reliability of the results. Second, the effectiveness of the fracking technique utilized in the study was dependent on the operator’s skill, which could have affected the outcomes. Third, scaffolds and atherectomy devices were not used in the study, which may limit the applicability of the results. Fourth, only calcified lesions were included, and thus, the efficacy of fracking in treating noncalcified lesions remains unknown. Finally, since the follow-up period was limited to one year, the clinical outcomes in the chronic phase are still unknown. Therefore, further studies with larger sample sizes, longer follow-up periods, and randomized designs are needed to evaluate the long-term safety and efficacy of this treatment approach.