Balloon-occlusion prostatic artery embolization (PAE) is as effective as conventional microcatheter PAE in the treatment of benign prostatic hyperplasia (BPH) with a potential to reduce nontarget embolization, Tiago Bilhim (Saint Louis Hospital, Lisbon, Portugal) and colleagues report in the Journal of Vascular and Interventional Radiology (JVIR). However, the authors were surprised to note that there was no clear advantage of balloon-occlusion PAE over the conventional technique.
The investigators set out to compare the safety and efficacy of these two types of PAE. In this single-centre, prospective, randomised, single-blind clinical trial, 89 patients with symptomatic BPH were assigned to conventional microcatheter PAE (43 patients) or balloon-occlusion PAE (46 patients), and were treated between November 2017 and November 2018. All patients were embolized with 300–500µm Embosphere microspheres (Merit Medical), and were evaluated one and six months post-procedure.
All efficacy variables improved in both groups with statistical significance, with the exception of International Index of Erectile Function, which remained constant in both groups, and prostate-specific antigen levels, which decreased significantly in the conventional microcatheter PAE group (0.9nb/mL±2.22; p=0.01).
Assessments at six months after PAE showed mean International Prostate Symptom Score (IPSS) reduction from baseline was 7.58±6.88 after conventional microcatheter PAE, and 8.30±8.12 after balloon-occlusion PAE (p=0.65).
Mean prostate volume reduction was 21.9cm3±51.6 (18.2%) after conventional microcatheter PAE and 6.15cm3±14.6 (7.3%) after balloon-occlusion PAE (p=0.05).
Additionally, Bilhim et al report no statistically significant difference in the average maximum pain reported within 24 hours after the procedure (0.74±1.31 and 0.93±1.70 in conventional microcatheter PAE and balloon-occlusion PAE groups, respectively; p=0.056).
Longer term data are needed to determine if the relapse rate is different between the two PAE procedural methods.
Comparing the two PAE procedures, Bilhim and colleagues are surprised by their results, writing: “Balloon-occlusion PAE relies on the potential to prevent reflux and to reverse blood flow in the anastomoses between the prostate and surrounding organs. Thus, it would be reasonable to expect fewer adverse events in balloon-occlusion PAE and less need for protective coil blockage of the prostatic anastomoses. These assumptions were not proven here, as the overall rate of adverse events was not significantly different between the two groups.”
Indeed, no major adverse events occurred in either group, whilst minor adverse events occurred in 23 patients (53.5%) in the conventional microcatheter PAE group, and in 26 patients (56.5%) in the balloon-occlusion PAE cohort. Penile skin lesions and rectal bleeding, which the study authors say can be due to nontarget embolization, only occurred in the conventional microcatheter PAE cohort: three patients (7.1%) had penile skin lesions and two (4.7%) had rectal bleeding.
Interpreting these findings, the investigators say that “these observations are probably clinically relevant, as they represent indirect measures of nontarget embolization”. They continue: “The lower rate of these adverse events [penile skin lesions and rectal bleeding] in the balloon-occlusion microcatheter PAE group (with no reported events) could be due to the protective features of balloon-occlusion. However, the wedged embolization technique used as opposed to a free-flow embolization and a low usage of protective coils (14%) could have led to a higher rate of nontarget embolization in the conventional microcatheter PAE group (n=5; 11.9%).”
Bilhim and colleagues recommend that future trials compare the two types of PAE procedures using radiopaque microspheres or macroaggregates, in an effort to clarify “any potential benefits related to reduced nontarget embolization in particular”.
When enumerating the potential benefits of balloon-occlusion PAE in comparison with conventional microcatheter PAE, Bilhim et al list reduced coil usage (as the placement of coils has been shown to increase procedural times and radiation exposure) and the establishment of an intraprostate negative pressure, which the authors claim “could likely allows the use of a larger amount of embolic volume”. If this latter benefit holds true, Bilhim and colleagues postulate that balloon-occlusion PAE “could lead to greater prostatic destruction, together with higher values of prostate-specific antigen in the 24 hours following embolization, and greater clinical relief”. However, this was not proven in the present study.
Furthermore, the authors note that their work corroborates earlier studies in showing that 5α-reductase inhibitors are not detrimental to the clinical outcomes after PAE. In fact, the present study “uncovered a potential positive interaction with PAE outcomes—that is, the use of 5α-reductase inhibitors before PAE may lead to better clinical outcomes”, according to Bilhim and colleagues.