Angle of covered self-expandable metallic stents after placement is a risk factor for recurrent biliary obstruction

ARTICLE HIGHLIGHTS

Research background

Covered self-expandable metallic stents (CSEMS) cause recurrent biliary obstruction (RBO), which prevents the continuation of treatment and causes the quality of life in patients with unresectable distal malignant biliary obstruction (MBO) to be poor. To date, sludge formation and food impaction have remained to be major causes of RBO. Recently, CSEMS with a low axial force (AF) to improve compatibility with the bile duct have been used frequently, with increasing concerns that they are likely to cause early RBO as a result of sludge formation and food impaction.

Research motivation

We hypothesized that the time to RBO (TRBO) of CSEMS with a low AF was short. We considered that proving this hypothesis has great significance in the management of patients with CSEMS placement in the clinical practice.

Research objectives

We aimed to evaluate whether the angle of CSEMS after placement is a risk factor for RBO in patients with unresectable distal MBO.

Research methods

Finally, we included 87 patients in this study. We divided the patients into two cohorts, RBO group and non-RBO group, and evaluated the risk factors for RBO including the angle of CSEMS after the placement. Using the SYNAPSE PACS system, we measured the obtuse angle of CSEMS after placement on an abdominal radiograph.

Research results

We found that the angle of CSEMS after placement was an independent risk factor for RBO. Further, we demonstrated that the cut-off value for the angle of CSEMS after placement was 130°, and that time to RBO in the < 130° group was significantly shorter than that in the ≥ 130° group. In our study, among patients who caused RBO of CSEMS in the < 130° angle group, 86% had elevated liver enzymes in the latest laboratory data before the occurrence of RBO, compared with previous laboratory data, and all patients were asymptomatic.

Research conclusions

The findings suggest that the angle of CSEMS after placement for unresectable distal MBO is a risk factor for RBO, and TRBO of CSEMS with a low AF is shorter than that of other CSEMS. Hence, while managing such patients, we suggest the replacement of CSEMS even in asymptomatic patients if the liver enzymes are elevated and the CSEMS angle is < 130°. Additionally, by deploying a new CSEMS with a high AF as needed, it could be possible to expect long-term maintenance without stent dysfunction.

Research perspectives

These results are novel and provide pertinent information for future stent management. However, further prospective studies with larger cohorts are needed to validate our findings.