Predictors of the Effects of Flow Diversion in Very Large and Giant Aneurysms

Abstract

Background and purpose: The treatment paradigm for very large and giant aneurysms has recently changed to flow diversion, in light of the results of the Pipeline for Uncoilable or Failed Aneurysms trial. However, the effects of flow diversion were definitely unknown. We explored this topic and identified the predictors of such effects.

Materials and methods: We retrospectively reviewed 51 patients with unruptured aneurysms admitted to our institution for flow diversion between February 2014 and August 2019. Patients were categorized into an effect group (no filling or remnant entry) and a no-effect group (subtotal or total filling). We evaluated the aneurysm size and shape, incorporation vessel, parent artery stenosis and curvature, stagnation of contrast medium within the aneurysm, use of balloon angioplasty, and intra-aneurysm thrombus as potential predictors of the effects of flow diversion.

Results: The effect group comprised 34 patients (66.7%, 34/51; no filling, 35.3%, 18/51; and remnant entry, 31.4%, 16/51). The no-effect group comprised 17 patients (33.3%, 17/51; subtotal filling, 29.4%, 15/51; and total filling, 3.9%, 2/51). An incorporation vessel and balloon angioplasty were independent risk factors for the no-effect group in multivariate logistic regression analyses (OR = 0.13 and 0.05; 95% confidence intervals, 0.02-0.62 and 0.00-0.32; P values, .021 and .004, respectively).

Conclusions: Flow diversion is effective for very large and giant aneurysms, but the outcomes require further improvement. The results of this study show that an incorporated vessel and excessive balloon angioplasty might compromise flow diversion. This finding can help improve the outcomes of flow diversion.

FIG 1.

This image shows the curvature type of the parent artery involving the neck region of the aneurysm. A, Non-outer type. B, Outer type.

FIG 2.

Remnant aneurysms are apparent close to the incorporated ophthalmic artery on 6-month follow-up angiography.

FIG 3.

High-velocity blood flow into the aneurysm was caused by proximal parent artery stenosis after flow diversion. Early artery phase (A) and late artery phase (B). The high-velocity blood flow disappears immediately (D) after balloon angioplasty in the stent (C).