Bifurcation lesions account for 20% of all percutaneous coronary interventions (PCI), with provisional stenting being the predominant strategy for treating de novo coronary bifurcation lesions [1, 2]. The process of stent placement in the main vessel (MV) may lead to plaque redistribution or carina shift, subsequently impacting the side branch (SB) [3]. This can escalate into SB complications ranging from ostial stenosis deterioration to complete SB occlusion, potentially resulting in perioperative myocardial infarction and adverse long-term outcomes [4, 5]. Previous studies have shown that SB ostial stenosis is an independent predictor of acute SB occlusion following MV stenting [6, 7]. Therefore, it is crucial to address SB ostium stenosis during bifurcation lesion interventions.

The jailed balloon technique (JBT) and jailed wire technique (JWT) are key strategies for protecting the SB and mitigating SB occlusion risk in complex bifurcation lesions [8, 9]. Despite their widespread use, comparative data on JBT and JWT is limited and has yielded mixed results [10, 11]. Studies indicate JWT was associated with fewer instances of SB occlusion following MV stenting in cases of severe stenosis at the SB or MV [10]. In contrast, the CIT-RESOLVE study showed that JBT provided superior SB protection compared to JWT [12], a finding contested by another research group [13]. This discrepancy underscores the need for further investigation to clarify the comparative efficacy of these techniques.

The evaluation of SB complications often relies on immediate angiographic results. However, accurately assessing SB ostial stenosis is challenging due to factors such as vessel overlap, angulations, stent struts obstructing the branch view, and image foreshortening [14]. These inherent limitations complicate the clarity of assessments.

Three-dimensional (3D) optical coherence tomography (OCT) has emerged as a sophisticated intravascular imaging tool, offering detailed insights into the coronary lumen and vessel wall. It facilitates an indirect yet precise assessment of the SB ostium area, overcoming the drawbacks of traditional imaging techniques [15, 16]. The effectiveness of 3D-OCT in accurately measuring the SB ostium area has been demonstrated, positioning it as a reliable alternative to direct OCT pullback examinations of the SB [15]. Given its potential, this imaging method is poised to significantly influence the interventional treatment of bifurcation lesions. To our knowledge, no studies have utilized 3D-OCT to assess the protective effect of JBT and JWT on the SB.

Therefore, the objective of this study was to evaluate the protective effects of JBT and JWT on the SB ostium using 3D-OCT. By employing this innovative approach, we anticipate the ability to provide more comprehensive data on the efficacy of JBT and JWT, thereby aiding in the clinical decision-making process.

To the best of our knowledge, this study is the first to compare the protective effect of the JBT and the JWT in bifurcation lesions using 3D-OCT. The key findings of this study can be summarized as follows: (1) The protective effect of JBT primarily stems from the impact of A-JBT. (2) The larger diameter of the jailed balloon, rather than the higher pressure, provides greater protection for the SB.

While SB ostium stenosis may worsen due to plaque or carina shift following MV stenting, adopting a single stent technique with SB stenting is still the recommended approach for treating coronary bifurcation lesions [19]. This clinical approach is justified by evidence showing that a smaller SB ostium area is associated with decreased fractional flow reserve values [20]. This correlation suggests that compromised SB integrity is a significant concern, and is likely to result in adverse clinical outcomes in PCI bifurcation [20]. Consequently, considerable efforts have been made to identify patients at risk for SB compromise following MV stent implantation [6, 8, 10, 21, 22, 23, 24]. Although the JBT and JWT techniques are established methods for preventing SB occlusion during bifurcation lesion treatment, their effectiveness in protecting against SB occlusion remains controversial [10, 11, 12, 13]. Previous studies have suggested that JBT is more effective than JWT in preventing SB occlusion, but these studies relied on visual assessment of coronary angiography or quantitative coronary angiography [8, 12]. However, visual estimation based on angiography or quantitative coronary angiography is not reliable for assessing the severity of SB lesions [14, 25]. Therefore, more accurate tools are needed to measure the extent of SB ostial stenosis.

As a state-of-the-art imaging modality, OCT plays a critical role in measuring the side branch ostium [16]. The accuracy of SB ostial area measurements using 3D-OCT in MV closely matches that of SB OCT pullback, suggesting that 3D-OCT guidance for optimal SB treatment is a viable and effective solution [15, 26]. Therefore, this study aimed to evaluate the impact of JBT versus JWT on the SB ostial area in bifurcation lesions treated with the single-stent approach. When considering all bifurcation lesions, JBT was associated with a relatively larger absolute SB ostium area compared to JWT. In the subgroup analysis, JBT demonstrated a superior protective effect, primarily attributed to A-JBT. In contrast, C-JBT did not show any discernible advantage over JWT. Previous studies have shown that A-JBT can prevent SB occlusion, and even improve SB functional blood flow compared to JWT [11, 27, 28]. This superiority of JBT over JWT was consistent across both true and non-true bifurcation lesion subgroups. Furthermore, PSM analysis was utilized to compensate for potential selection bias in retrospective observational studies and to facilitate an intention-to-treat analysis. Although no statistical difference was observed, there was a trend suggesting that the increase in SB ostium area may be greater in the JBT group compared to the JWT group.

Carina and plaque shifts are the primary mechanisms leading to SB ostial compromise at the SB following MV stent implantation [29]. The protective effect of JBT on SB ostium may be attributed to its capacity to mitigate these shifts. We have demonstrated that the utilization of a large diameter jailed balloon and A-JBT provide superior protection in true bifurcation lesions. Subgroup analysis revealed that a larger jailed balloon diameter ($>$2.0 mm) produced greater SB ostium area differences when compared to a smaller diameter ($\le$2.0 mm). Despite these insights, there is a notable gap in research directly comparing jailed balloon diameter and SB protection, necessitating additional studies to confirm our findings. A previous study found no difference in the level of dilation pressure of the jailed balloon and its protective effect on SB [30], which was confirmed by our results.

Several studies have assessed the protective effect of JBT on SB through coronary angiography, finding JBT superior to JWT in reducing branch occlusion, but not in long-term patient outcomes [11, 12]. Our study aligns with these findings to an extent, confirming that JBT, particularly A-JBT, offers more effective protection of the SB ostium area compared to JWT. Nonetheless, the difference in the increase of the SB ostium area between the JBT and JWT groups was modest, at an average of 0.66 mm² in the JBT group compared to the JWT group (0.41 mm² vs. –0.25 mm²). This relatively small disparity in SB ostium area enlargement may explain the absence of observed significant differences in the long-term prognosis of patients treated with either technique [11].

The JBT group was characterized by a smaller initial SB ostium area and a greater incidence of true bifurcation cases, which aligns with observations from clinical practice. Despite the strategic use of JBT, the extent of SB ostium enlargement following PCI in the JBT group was modest, with a mean difference of 0.41 mm². This finding suggests that A-JBT, particularly when utilizing larger diameter balloons, may be more suitable for treating relatively large SBs with ostial stenosis [31]. Such scenarios include bifurcations of the non-left main trunk and the left main trunk when associated with a smaller left circumflex artery [31]. However, the implementation of A-JBT necessitates a careful consideration of potential risks, including SB dissection, the entrapment of devices, and stent deformation, which could complicate the procedure [32, 33]. In our study, balloons ranging from 1.5–2.5 mm were used for SB treatment via JBT, and no significant complications were reported, suggesting a cautious yet effective application for this technique.

This study has several limitations that merit acknowledgment. Firstly, its retrospective design inherently carries the risk of introducing various certain biases into the findings. Secondly, the selection of patients and procedural techniques was subject to the operating clinician’s subjective preferences, potentially leading to selection bias. However, it’s noteworthy that the basic demographic and clinical characteristics, such as age, sex, and clinical diagnosis were similar across the groups, somewhat mitigating concerns related to selection bias. Thirdly, the initial SB ostium area was smaller in the JBT group compared to the JWT group before undergoing PCI. To counteract these confounding factors, PSM was employed, aiming to equalize these variables and reduce the impact of biases on the study’s outcomes.

Based on the analysis of the series OCT imaging database, A-JBT was found to be superior to JWT in preserving SB ostial area in single stent procedures. Notably, the efficacy of protection afforded to the SB was more strongly associated with the diameter of the jailed balloon than with the pressure applied during dilation. Therefore, when using the provisional stenting technique for bifurcation lesions, utilizing a larger diameter balloon and ensuring its protection with A-JBT appears to be a preferable strategy for SB preservation. Nonetheless, the validation of these findings necessitates further investigation through prospective studies and randomized clinical trials to solidify the evidence base supporting this approach.

OCT, optical coherence tomography; SB, side branch; MV, main vessel; 3D, three-dimensional; JWT, jailed wire technique; JBT, jailed balloon technique; PCI, percutaneous coronary intervention; PSM, propensity score matching.

The data that support the findings of this study are available from the corresponding author upon reasonable request.

JC and QJ designed the research study. JC, XW and QJ performed the research. JC analysed the data. JC wrote the manuscript. YC conceived of the study and participated in supervising data quality. All authors contributed to editorial changes in the manuscript. All authors read and approved the final manuscript. All authors have participated sufficiently in the work and agreed to be accountable for all aspects of the work.

The study protocol was approved by the Institutional Review Board of the General Hospital of Chinese People’s Liberation Army (No. S2020-196–01), and it adheres to the Helsinki Declaration. All patients provided written consent for the use of their imaging data.

All authors gratefully acknowledge the staff at the Chinese People’s Liberation Army General Hospital’s Department of Cardiology and Cardiac catheterization room for their contributions to this study.

This research received no external funding.

The authors declare no conflict of interest.