In this all-comer prospective study, we investigated the prognostic significance of various procedural characteristics on angiographic outcomes of DCB treatment for de novo coronary lesions. The key findings of the present study were as follows: First, notable disparities were observed in procedural characteristics between the lesions demonstrating successful, stent-like DCB results (SR) at angiographic follow-up and those not (Non-SR), particularly with the use of balloons with larger B-A ratio identified as an independent predictor of the success. Second, the significance of this distinct procedural step was corroborated by an improved immediate post-DCB angiographic outcomes, with a greater acute luminal gain and a larger MLD. Finally, these differences ultimately translated into a more favorable follow-up angiographic outcome in the SR group, characterized by a larger final MLD and positive vessel remodeling (Fig. 4).
Current expert consensus documents commonly recommend a B-A ratio of approximately 0.8 to 1.0 for DCB angioplasty.1,4 This recommended range considered to balance adequate lesion expansion and drug delivery against the potential risks of vessel injury. However, these recommendations are largely based on expert experience and consensus opinion, rather than robust clinical data.1,4 Moreover, these guidelines do not provide detailed guidance on the measurement methods for determining RVD, such as whether visual assessment or QCA should be used, or whether to consider the distal, proximal, or mean RVD.
Historically, in the pre-stent, percutaneous transluminal coronary angioplasty (PTCA) era, a higher B-A ratio of > 1.0 was often suggested.8,9 Specifically, lesion preparation conducted by balloons with B-A ratio ranging from 0.9 to 1.3, as assessed by cine angiography, yielded optimal outcomes by minimizing dissections and residual stenosis.10 The positive impact of oversized devices on procedural and clinical outcomes was also well documented for the DES therapy.11 These insights from the historical studies are particularly relevant to our findings, emphasizing the importance of oversized ballooning in lesion preparation. Specifically, our data demonstrated that a 0.1 increase in the B-A ratio was associated with 43.2% increase in the odds of achieving favorable angiographic outcome at the median 8-month follow-up. Collectively, the current B-A ratio recommendations in DCB treatment for de novo CAD should be refined to establish optimal ranges and safety limits in light of this context.
It is widely acknowledged that RVD is typically larger by intravascular imaging (IVI) than by angiography.12 An earlier study by Stone GW et al. demonstrated that IVUS-guidance, compared to angiography-guided PTCA, resulted in balloon upsizing in 73% of participants, increasing B-A ratio from 1.12 ± 0.15 to 1.30 ± 0.17 (P < 0.0001).8 This IVUS-guided PTCA led to a significant decrease in mean angiographic %DS and an increase in MLD, without significantly increasing peri-procedural complications.8 The benefits of IVUS- versus angiography-guided PCI have also been well recognized in DES therapy.13,14 In the ULTIMATE trial, IVUS-guided PCI led to more frequent post-dilation using larger balloons at higher pressures, resulting in a significantly greater MLD after DES implantation.13,14 These specific procedural characteristics are suggested to translate into improved clinical outcomes.13,14 Furthermore, a pooled analysis based on two randomized clinical trials (IVUS-XPL and ULTIMATE), stent oversizing of stent-to-vessel ratio of 1.1 to 1.3 was associated with better angiographic and clinical outcomes.13–16 Given these insights, there is a growing need to explore how IVI guidance can influence DCB treatment in de novo CAD. Our analysis provides evidence that IVUS guidance led to a higher B-A ratio of 1.23 ± 0.14 through a more detailed assessment of target lesion anatomy. Further studies are warranted to determine more detailed, systematic balloon sizing strategy based on IVI and its impact on patient outcomes after DCB treatment.
A previous study demonstrated that post-procedural MLD significantly predicted successful DCB treatment in de novo lesions.17 Our study consistently demonstrated these findings, underscoring the importance of achieving sufficient luminal enlargement immediately after the procedure. Numerous studies on stent-based PCI have consistently shown a strong association between larger final stent dimensions and reduced rates of ISR, supporting the concept of “the larger, the better”.14,16,18,19 In the context of DCB treatment, this relationship is particularly pertinent since DCBs, unlike stents, do not provide scaffolding to maintain vessel patency. Evidences from the PTCA era showed that repeated balloon overstretch using balloons with bigger B-A ratio alleviated early vessel recoil.20 Furthermore, adequate luminal gain after PCI might facilitate the restoration of coronary laminar flow, leading to a favorable shear stress environment. Shear stress, the force exerted by blood flow on the vessel wall, plays a pivotal role in vascular biology and regulating vessel healing.21 In the case of DCB treatment, enlarged lumen without residual metallic scaffold might promote a favorable hemodynamic microenvironment, potentially reducing the risks of abnormal vasomotion, thrombus formation, and neointimal proliferation/restenosis.21,22
In our study, specialty balloons, predominantly scoring balloons, were more frequently used in SR group. However, they were not identified as an independent predictor in the multivariable logistic regression analysis. This observation should be interpreted with caution, as it does not necessarily imply that scoring balloons are ineffective. Rather, their impact may be overshadowed in the presence of stronger predictive factors such as B-A ratio or post-DCB MLD. Scoring balloons play a crucial role in controlled plaque modification, achieving sufficient luminal gain, and reducing the risk of serious vessel injury during the course of various endovascular intervention.23,24 Their positive impact in DCB treatment was well demonstrated in treating ISR.25,26 A recent study demonstrated that the utilization of a scoring balloon was associated with reduced risk of severe dissection and more favorable angiographic outcomes in treating de novo coronary lesions.27 Accordingly, despite the larger maximum balloon diameter and B-A ratio observed in the SR group compared to the Non-SR group, there was no significant difference in the occurrence of coronary dissection in our study. These findings underscore the complexity of factors influencing DCB treatment outcomes and suggests that scoring balloons might still play a valuable, albeit not singularly decisive, role within the broader context of procedural strategy. Further research is needed to fully understand their role, especially in the treatment of complex lesions where controlled plaque modification and effective drug delivery are crucial.
In our study, only paclitaxel-coated balloons were used, which limits the generalizability of our findings to limus-coated balloons. The AUC value obtained from the ROC analysis for the B-A ratio was relatively modest. Given the current recommendation of a B-A ratio between 0.8 and 1.0, attending interventionists tend to adhere closely this range, resulting in constrained variability in B-A ratio values.1,4 Such limited variability or high correlation among procedural variables can compromise the discriminatory capacity of ROC model, thereby yielding a lower AUC.28 Analyzing a more extensive dataset and incorporating diverse pre-dilation strategies in the future studies may contribute to achieving higher AUC values.
Our study contributes significantly to the ongoing discussion about the optimal procedural steps and the appropriate application of DCB therapeutic strategies in de novo CAD. Given the historical precedents in the PTCA era and insights from stent therapy, specifically the concept of “the larger, the better”, our findings suggest the potential benefits of considering a higher B-A ratio to achieve maximal final MLD for successful DCB treatment. Future research, especially studies incorporating IVI, is essential to further optimize DCB treatment strategies and improve patient outcomes.