Hydrogel coil trumps standard coil for aneurysm recurrence
Treatment with the second-generation hydrogel coils significantly reduces the rate of aneurysm recurrence compared with standard platinum coils, with no increase in adverse events, reveals the HEAT* study presented at ISC 2019.
“The findings of the HEAT trial validate the improved efficacy of the hydrogel coils over standard platinum coils in treating small-to-medium sized aneurysms,” said Dr Bernard Bendok from the Mayo Clinic in Phoenix, Arizona, US.
Although the first-generation hydrogel coils yielded lower recurrence over the long term than bare platinum coils, its use was limited by several technical challenges.
“The second-generation hydrogel-coated platinum coil was developed to emulate the ease of use of platinum coils … [and] to increase the packing density of coiled aneurysm and ensure their long-term obliteration,” explained Bendok.
Over 18–24 months of follow-up, the primary endpoint of aneurysm recurrence rated on the Raymond-Roy scale was less common in patients who received the hydrogel coils than those treated with the platinum coils (4.4 percent vs 15.4 percent; p<0.001). [ISC 2019, abstract LB20]
The rate of aneurysm recurrence graded on the Meyer scale was also significantly lower in the hydrogel coil group compared with the platinum coil group (13 percent vs 27 percent; p<0.001), regardless of whether it was a major (p=0.016) or a minor recanalization (p=0.044).
“The second-generation hydrogel coil resulted in better long-term durability than bare platinum coils,” observed Bendok.
Hydrogen coils also showed significantly higher packing density than platinum coils (32.5 percent vs 24.7 percent; p<0.001), which allows them to fill more space in the aneurysm and prevent recanalization. Bendok attributed this feature to the hydrogel, which can expand in the aneurysm and therefore fill more dead space within.
There were no significant differences in other secondary outcomes such as retreatment rate (p=0.162) and mRS** scores between groups.
In addition, similar improvement in quality of life from baseline was seen in both groups, as assessed on the SF-36*** v2, although the underlying mechanism leading to the improvement has yet to be determined, according to Bendok.
Safety outcomes were also similar between the two groups, with no significant difference in the rates of adverse events related to coil or procedure (22 percent vs 25 percent; p=0.352) or mortality (2 percent vs 3 percent; p=0.641).
“[The findings showed that] second-generation hydrogel coils have significant effect in reducing recurrence for 3–14 mm aneurysms [with] no difference in adverse events,” Bendok concluded.
The multicentre study enrolled 600 patients (mean age ~57 year, more than three quarters were female) with 3–14 mm brain aneurysms (majority were unruptured) for which treatment with endovascular coiling was indicated. They were randomized 1:1 to receive hydrogel-coated platinum coils or bare platinum coils.
The hydrogel coil (HydroCoil Embolization System) used in the study has been approved by the US FDA, and HEAT constitutes an investigator-initiated postmarketing trial.