DELTA Trial: Does Embolization With Larger Coils Lead to Better Treatment of Aneurysms Trial

Endovascular treatment with platinum coils is safe and effective in preventing rebleeding of
intracranial aneurysms. Unfortunately, endovascular treatment of aneurysms with coils has
been associated with incomplete occlusion at initial treatment (remnant) or at follow-up
(recurrence). This in some studies has been as high as 20%. While many such aneurysm remnants
or recurrences exhibit benign behavior, many require retreatment to prevent future
hemorrhage.

A recent randomized controlled trial of aneurysm coiling revealed that aneurysms between 2
and 9.9 mm diameter were more likely to have an improved angiographic and composite clinical
outcome when treated with hydrogel-coated coils, an improvement inferred to result from
higher packing density afforded by hydrogel expansion(1). The use of hydrogel coils is
associated with technical difficulties related to expansion and limited time for deployment.
The investigators theorize that similar results could be achieved by using more voluminous
bare platinum coils, leading to improved packing density compared to smaller caliber coils,
and thus result in lower incidence of remnants or residuals. The relationship between packing
densities and composite clinical endpoints having never been shown in a robust fashion, the
investigators therefore propose a randomized clinical trial opposing coiling with soft
15-caliber coils to 10-caliber bare platinum coils in aneurysms varying in size from 3 to 9.9
mm.

To test the hypothesis that 15-caliber coiling systems are superior to standard 10-caliber
coils in achieving better composite outcomes, the investigators propose the DELTA trial: Does
Embolization with Larger coils lead to better Treatment of Aneurysms trial, a randomized
controlled blinded trial with 2 subgroups of 282 patients each, 564 total:

Subgroup 1: Coiled with a maximum proportion of 15-caliber coils as conditions allow Subgroup
2: Coiled with 10-caliber coils.