Background
As a chronic respiratory disease, bronchiectasis is characterized by irreversible bronchial dilatation [
1]. Patients with bronchiectasis often experience chronic respiratory symptoms, such as cough, purulent sputum, hemoptysis, dyspnea, and recurrent infections. Moreover, approximately 70% of Chinese bronchiectasis patients experience hemoptysis, placing a burden on healthcare systems [
2]. For these patients, many studies have shown that bronchial artery embolization (BAE) is an effective and minimally invasive option [
3‐
10]. However, the rate of clinical failure after PAE is relatively high. Specifically, 5% of patients still have moderate to severe hemoptysis within 1 month of embolization, and long-term results show that approximately 20% of patients have a recurrence of hemoptysis after successful embolization [
4].
In BAE, the culprit bronchial artery is cannulated and typically embolized using a variety of embolizers, including coils, polyvinyl alcohol (PVA), microspheres, gelatin sponges, etc. The efficacy of PVA and microspheres as embolic agents for BAE has been established through clinical experience and experimental studies, making them the prevailing standard [
3‐
10,
16‐
19]. In comparison to PVA, microspheres exhibit several benefits, including precise sizing, resistance to aggregation, and satisfactory elasticity [
6,
7]. Despite their excellent physical properties, microspheres for the treatment of bronchial artery embolization (BAE) in patients with hemoptysis have shown similar clinical results to PVA, according to a recent study [
9]. Nonetheless, many studies compare different embolic agents, and we have found only a few clinical trials that compare different sizes of specific embolic agents. Furthermore, the determination of the optimal size of Embosphere microspheres for BAE remains inconclusive, as the majority of centers employ particles with diameters ranging from 500 to 750 μm or 700–900 μm [
2‐
8].
The purpose of this retrospective study was to compare the efficacy and safety profiles of microspheres 500–750 versus (vs.) 700–900 μm in size for BAE treatment in patients with bronchiectasis-related hemoptysis, which helped to provide evidence for embolic agent selection.
Conclusions
In this retrospective study, we evaluated the treatment effectiveness and safety profile of BAE with smaller (500–750 μm) versus larger (700–900 μm) Embosphere microspheres for the treatment of bronchiectasis-related hemoptysis. We found that larger microspheric particles (700–900 μm in size) have a significantly lower cost of embolic microspheres. However, the duration of hospitalization, complications, and hemoptysis-free survival rates (1 year, 2 years, and 3 years) were similar between groups. Furthermore, our results indicated that the cystic type of bronchiectasis and SPSs were independent predictive factors for increased hemoptysis recurrence risk.
In recent decades, various agents have been employed for bronchial artery embolization. Nonabsorbable Embosphere microspheres, which are relatively new embolic agents, have several advantages, including excellent biocompatibility, aggregation resistance, and satisfying elasticity [
9,
13]. As a result, they benefit from preventing microcatheter occlusion and have been widely used to treat various diseases. For example, a prospective multicenter clinical trial in Japan illustrated that transarterial embolization (TAE) using tris acryl gelatin microspheres (TGMs) for hypervascular tumors was technically feasible and safe for devascularization [
14]. In addition, a recent study illustrated that embosphere embolic microspheres have good efficacy and safety in the treatment of prostatic hyperplasia rupture and hemorrhage, with a mild adverse reaction compared to the gel foam embolic agent [
15]. On the other hand, the efficacy and safety of BAE with PVA in the control of hemoptysis was demonstrated. PVA is also nonabsorbable but has a nonuniform shape, resulting in an increased tendency for clumping, which may cause catheter or proximal arterial obstruction during infusion, which may increase the risk of recurrent hemoptysis in the long term [
6,
7,
16,
17]. However, a previous study demonstrated similar efficacy and safety profiles of microspheres versus PVA for BAE in patients with hemoptysis [
9]. To the best of our knowledge, the different sizes of specific embolic agents for BAE for patients with hemoptysis due to varying causes have not been properly investigated to date.
In our study, we showed that the hemoptysis-free survival rates were (group A vs. group B: 85.9% vs. 88.4%) at 1 year, (group A vs. group B: 75.8% vs. 81.2%) at 2 years, and (group A vs. group B: 62.9% vs. 59.4%) at 3 years. Even though we should interpret these data with caution since patient prognoses may differ depending on their underlying diseases, the procedural outcomes were favorable and comparable with those of other embolization materials, such as metallic coils, PVA, or NBCA. For example, Ishikawa et al. [
18] reported that the 1-year and 3-year hemoptysis-free survival rates of BAE with metallic coils (
n = 489) were 86.9% and 57.6%, respectively. Woo et al [
19] reported that the 1-year and 3-year hemoptysis-free survival rates of ssBAE with PVA (
n = 293) were 77% and 68%, respectively, and those with NBCA (
n = 113) were 88% and 85%, respectively. However, the incidence of recurrent hemoptysis in our study was slightly higher than that reported in the data using 300–500 μm Embosphere microspheres (
n = 90), which reported that the 1-year hemoptysis-free survival rate after BAE was 91.1% [
9]. The possible explanations might include the following: (1) The sample size in our study was relatively large, which could provide more statistical validation. (2) The higher proportion of patients with cystic bronchiectasis, has been associated with a very high likelihood of recurrent bleeding. Moreover, based on the evidence to date, the particle size selected for a particular embolization procedure is determined by the desired level of occlusion (i.e., proximal or distal). In general, the use of small particles results in a more distal occlusion. Microparticles with larger diameters might have a disadvantage in occluding the index bronchial artery more proximally than preferred, which could lead to recurrent hemoptysis from systemic collaterals [
20]. However, we did not observe a decreased hemoptysis recurrence rate in Embosphere microspheres of 500–750 μm compared with 700–900 μm microspheres in our study. The results were similar to those of a previous study. Although Kucukay [
6] used Embosphere microspheres with a diameter of 700–900 μm and Corr [
7] used microspheres with a diameter of 500–750 μm, there was no significant difference in the rate of recurrence of hemoptysis (8.1 vs. 13%). The possible reasons include the following: (1) This risk of hemoptysis recurrence can be diminished by using a microcatheter. In other words, placing it in a possible closer location near the abnormal vasculature results in less recurrent hemoptysis from nonbronchial systemic collaterals. (2) Based on the available evidence, the main causes of recurrent hemoptysis were failure to identify the culprit vessel, recanalization of the embolized bronchial artery, or progression of the underlying lung disease rather than the embolic agents used, which might explain why 500–750 μm microspheres displayed similar hemoptysis recurrence rates as 700–900 μm microspheres. Of note, we found that SPSs and the bronchiectasis subtype (the degree of cystic) were independently associated with recurrence. The possible explanations might include the following: (1) The use of small microspheres is potentially risky for nontargeted embolization of the viscera, so the use of particles smaller than 325 μm has been abandoned [
21]. (2) Furthermore, with the help of using a microcatheter and placing it at the possible closest location near the abnormal vasculature, it decreased the possibility of nontarget embolization of the spinal artery as well as the risk of BAE-related neurologic complications. In addition, to complete the cessation of abnormal-looking bronchial arterial flow and stop bleeding, fewer bottles of large microspheres (700–900 μm) are used. Considering the comparative cost-efficacy, the use of 700–900 μm microspheres was associated with lower inpatient costs for patients undergoing BAE when compared with 500–750 μm microspheres, and it was more reasonable to recommend the use of 700–900 μm microspheres rather than 500–750 μm microspheres.
In terms of safety, there was no statistically significant difference in complications between BAE using 500–750 μm Embosphere microspheres and BAE using 700–900 μm microspheres, and no major complications were observed. The occurrence of minor complications, such as cough/expectoration, fever, chest pain, nausea/vomiting, allergy, ecchymosis at the puncture site, and dyspnea, was frequently observed in BAE procedures, consistent with findings from previous studies [
4,
5,
8,
9]. One potential explanation for the absence of major complications is that the microspheres used in the procedure had diameters of either 500–750 μm or 700–900 μm, allowing them to be appropriately positioned in the pulmonary artery without causing occlusion of the normal peripheral branches. This feature reduces the likelihood of more severe complications (such as myocardial infarction or stroke) caused by ischemia.
Our study aimed to address a gap in the literature by conducting a comparative analysis of the efficacy and safety profiles of microspheres ranging from 500 to 750 μm and 700–900 μm, specifically in the context of bronchial artery embolization (BAE) treatment for hemoptysis patients. Our findings indicate that the 500–750 μm microspheres exhibit comparable efficacy and safety to the 700–900 μm microspheres in controlling hemoptysis. Additionally, considering the more favorable cost associated with the 700–900 μm microspheres compared to the 500–750 μm microspheres, our evidence suggests that the former may serve as a viable alternative in BAE treatment. However, the present study still has some limitations, including (1) considering the small sample size in our study, more patients from multiple centers are necessary for statistical validation; (2) a patient’s prognosis was also influenced by the management of their underlying respiratory disorders, such as antibiotic usage, blood oxygen levels, and inflammation index; (3) this is a retrospective observational study conducted in a single center. The choice of the diameter of the embolized microspheres is determined by the personal experience of different operators, which might result in a selective bias for embolic agents.
In summary, the utilization of BAE with 700–900 μm microspheres demonstrates similar levels of effectiveness and safety as BAE with 500–700 μm microspheres in the treatment of hemoptysis. However, it is important to note that the former option is less economically efficient. Consequently, it is advisable to prioritize the use of 700–900 μm microspheres for managing hemoptysis resulting from bronchiectasis.
Others♦ included IPA, ICA, IMA, TTA or CTA IPA inferior phrenic artery, ICA intercostal artery, IMA internal mammary artery, TTA thyrocervical trunk artery, CTA costocervical trunk artery, and SPSs systemic arterial-pulmonary circulation shunts. BA Bronchial artery.
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