Repeat prostatic artery embolization (PAE) is safe and effective for recurrence of lower urinary tract symptoms (LUTS) or acute urinary retention caused by benign prostatic hyperplasia (BPH), and may be used as a first-line treatment option. However, it has limited impact in patients who did not show a response to the initial embolization procedure. This is the conclusion presented by Nuno Costa (Saint Louis Hospital, Lisbon, Portugal) et al in their recent publication in Journal of Vascular and Interventional Radiology (JVIR).
The study investigators set out to evaluate the safety and efficacy of repeat PAE for LUTS caused by BPH, to define revascularisation patterns, and to establish predictors of outcome in larger cohort of treated patients. Costa and colleagues conducted a single-centre, retrospective study investigating 108 patients with BPH and clinical failure after PAE who then underwent repeat PAE between June 2009 and October 2018. Of these 108, 39 did not show a response to their initial PAE, and 69 had an initially favourable response in the first six months following PAE, but then experienced relapsing symptoms.
Clinical failure after initial PAE, as seen in the 39 non-responders, was defined as improvement in International Prostate Symptom Score (IPSS) after PAE of less than 25%, an IPSS after PAE of more than 15 points, no improvement in quality of life related to LUTS or a quality of life score greater than three points, acute urinary retention after PAE, and need for any additional medical or invasive therapy for LUTS.
The cumulative probability of clinical success at 12 months following repeat PAE was higher for patients who initially responded positively to embolization and were subsequently treated for a recurrence of initial symptoms than for patients who did not show a response at all to initial PAE: 56.7% versus 28.2%.
Indeed, for patients with symptom relapse after initial PAE, the clinical outcomes were comparable to those reported for PAE: mean IPSS improvement of 9.5 points, mean quality of life improvement of 1.3 points, and clinical success rates of 84% at one month, and more than 50% at mid-term and long-term follow-up appointments. Costa et al suggest that “these results may justify repeat PAE”.
They continue: “Of note, the subjective parameters of LUTS (IPSS/ quality of life scores) were not the only improvements noted after repeat PAE. Objective parameters such as prostate volume, postvoid residual volume, peak urinary flow [Qmax], and prostate-specific antigen level also showed significant improvements after repeat PAE.” They point out that the difference between non-responders and relapsers after repeat PAE were only observed in the IPSS/ quality of life analyses.
Speaking to Interventional News, Tiago Bilhim (Saint Louis Hospital, Lisbon, Portugal), a co-author of the JVIR paper, says: “This study is important because it is not uncommon to follow-up patients after PAE that still have residual LUTS and that may need additional treatments. These treatment options include medical management, surgery, and repeat PAE. In order to advise patients that still have LUTS after PAE about the best treatment options, one should have a clear idea on the potential outcomes from repeat PAE. We have previously shown [in a 2016 Radiology paper by Bilhim et al] that patient selection is important to improve outcomes.”
Up to 20% of PAE patients undergo repeat intervention after one year, with a minority of clinical failures occurring in patients who experience symptom relapse after initial improvement (80% of clinical failures never show any improvement post-procedurally, and are in the non-responders category of this study). By demonstrating the safety and efficacy of repeat PAE, the investigators hope that this clinical study sheds some light on the treatment options available for patients who are deemed clinical failures following embolization.
“The present study […] expands on the concept that not all patients respond to PAE the same way, and that patient selection plays a pivotal role in improving clinical outcomes,” the authors note. “Even with a technical success rate of 100% and a unilateral repeat PAE rate lower than 6% (similar between relapsers and non-responders), clinical outcomes in non-responders were inferior to those reported for PAE. Even though as many as 17% of patients who never showed a response to PAE may still exhibit clinical success 24 months after repeat PAE, the vast majority of these patients do not show improvement. Therefore, repeat PAE should probably be avoided in patients who do not show a response to initial PAE.”
Expanding on this idea, Bilhim tells this newspaper: “In this study, we prove once more that patient selection rather than PAE technique has a profound impact on outcomes. PAE is not a ‘perfect fit’ in all patients with LUTS and BPH, with up to 25% of clinical failures despite optimal technique. Correlation of clinical outcomes after PAE with prostate volume reduction are not clear, with many patients improving LUTS with minimum prostate volume reduction and vice-versa. We now know that patient factors play a role. A lot of studies exist nowadays looking at predictors of clinical outcome for PAE.”
Some identified predictors of clinical outcome listed by Bilhim include:
- Baseline prostate volume—patients with a prostate volume <40cc have worse clinical outcomes. However, outcomes are not significantly different for patients with a prostate volume >40cc (including large or very large prostates). This means that larger prostates do not necessarily mean better outcomes. It is rather the other way around. Smaller prostates do worse after PAE.
- Avoid pedunculated median lobes—avoid all prostates with a median lobe morphology that is taller than wide.
- Patients under acute retention and large CG adenomas are good candidates—patients with prostate morphology with a central gland that is responsible for more than 50% of the whole prostate volume, with large central gland adenomas and those under acute urinary retention have very good outcomes with PAE.
- Old patients—possible to have worse outcomes and more challenging PAE procedures
- Patients with very severe baseline IPSS scores (>23 points) have a higher risk of clinical failure—PAE induces a mean IPSS reduction of 12–15 points. If your baseline is 30 points, this means that the probability of ending up with residual LUTS (>15 points) after PAE is very high. Again, this is important when counselling patients.
The embolization procedure
Patients were treated in an outpatient setting by a team of experienced interventional radiologists: two with nine years of experience with PAE each, one with four years experience, and one with one years experience. PAE was performed under local anaesthesia by a unilateral or bilateral femoral approach “wherever feasible”, the authors describe, stating that this was “usually through the right femoral artery”. In total, a unilateral femoral approach was used in 101 patients, and a bilateral approach in seven patients.
Embolization was performed with different embolic agents, including: non-spherical polyvinyl alcohol (PVA) particles (100–300μm), spherical PVA particles (Bead Block 100–300μm and 300–500μm; BTG International, London, UK), tris-acryl gelatin microspheres (Embosphere 100–300μm and 300–500μm; Merit Medical), and Polyzene-coated hydrogel microspheres (Embozene 250μm and 400μm; CeloNova, San Antonio, Texas).
Repeat PAE was considered more technically challenging than the initial embolization procedure: at 75 minutes (range: 20–120 minutes), the median procedure time of the repeat embolization was significantly higher versus initial PAE. Microspheres were used more often in repeat PAE procedures than the initial embolization, but Costa et al acknowledge that this “reflects a temporal trend rather than an intended method”.
There were no major complications. Among the 108 patients, 104 (96.3%) were discharged three to six hours after PAE, and the other four (3.7%) spent the night in the hospital and were discharged the next morning (18 hours later) per personal preference.
The endpoint of embolization was occlusion of all vessels to the prostate and reflux toward the prostatic artery. Embolization of at least one prostatic artery was considered a technically successful repeat PAE—repeat PAE was technically successful in all patients.