Reply:

We have read with great interest the letter of Pelz and Lownie, and we are grateful for their interesting comments regarding our paper on the WEBCAST-2 study.¹ We wish to make the following comments in response.

1. Because Pelz and Lownie are only challenging the “high” efficacy of WEB treatment, it probably implies that they concur with the high safety profile of the WEB device reported in WEBCAST-2. This is the primary concern when dealing with aneurysm treatment, and all published results of good clinical practice studies evaluating WEB (WEBCAST, French Observatory, and WEB-IT) have indeed confirmed similar high safety results: low morbidity (between 0.7% and 3.2%) and no mortality at 1 month.^2⇓–4 For reference, the meta-analysis cited by Pelz and Lownie reports mortality of 1.7% for surgical treatment of unruptured aneurysms, with the rate of unfavorable outcome at 6.7%.⁵

2. Pelz and Lownie are probably right when they write that “high” efficacy might not be the appropriate wording to qualify WEBCAST-2 anatomical results. Still, the rate of adequate occlusion at 1 year is 80.0%, consistent with observations from other WEB good clinical practice studies.^2,3 Although we know that neck remnant is rarely associated with rupture or rerupture, adequate occlusion is really what matters once safety is confirmed. It is also important to point out that patients with wide-neck bifurcation aneurysms—the target population of the WEBCAST-2 study—represent a challenging and difficult-to-treat population, regardless of the treatment technique. We actually agree that long-term follow-up is needed to properly evaluate the stability of aneurysm treatment and claim “high” efficacy. Long-term follow-up has been obtained in a small, retrospective European series, but the most important data will come from the good clinical practice studies where 5 years' follow-up is foreseen.⁶

3. Interestingly, Pelz and Lownie are comparing the efficacy of WEB treatment with surgical treatment. Kotowski et al⁵ report 2 interesting facts in their meta-analysis: aneurysm occlusion data are missing for 82.2% of all clipped aneurysms in the analyzed series, and there was no long-term follow-up available. With that in mind, can we scientifically consider surgical treatment “effective” from a long-term anatomic standpoint?

• © 2017 by American Journal of Neuroradiology