The Hydrogel Endovascular Aneurysm Treatment Trial (HEAT): A Randomized Controlled Trial of the Second-Generation Hydrogel Coil

Abstract

BACKGROUND Aneurysm recurrence after coiling has been associated with aneurysm growth, (re)hemorrhage, and a greater need for follow-up. The second-generation HydroCoil Embolic System (HES; MicroVention, Inc) consists of a platinum core with integrated hydrogel and was developed to reduce recurrence through enhancing packing density and healing within the aneurysm. OBJECTIVE To compare recurrence between the second-generation HES and bare platinum coil (BPC) in the new-generation Hydrogel Endovascular Aneurysm Treatment Trial (HEAT). METHODS HEAT is a randomized, controlled trial that enrolled subjects with ruptured or unruptured 3- to 14-mm intracranial aneurysms amenable to coiling. The primary endpoint was aneurysm recurrence using the Raymond-Roy scale. Secondary endpoints included minor and major recurrence, packing density, adverse events related to the procedure and/or device, mortality, initial complete occlusion, aneurysm retreatment, hemorrhage from target aneurysm during follow-up, aneurysm occlusion stability, and clinical outcome at final follow-up. RESULTS A total of 600 patients were randomized (HES, n = 297 and BPC, n = 303), including 28% with ruptured aneurysms. Recurrence occurred in 11 (4.4%) subjects in the HES arm and 44 (15.4%) subjects in the BPC arm (P = .002). While the initial occlusion rate was higher with BPC, the packing density and both major and minor recurrence rates were in favor of HES. Secondary endpoints including adverse events, retreatment, hemorrhage, mortality, and clinical outcome did not differ between arms. CONCLUSION Coiling of small-to-medium aneurysms with second-generation HES resulted in less recurrence when compared to BPC, without increased harm. These data further support the use of the second-generation HES for the embolization of intracranial aneurysms. Video Abstract

Long-term follow-up results of the SMART coil in the endovascular treatment of intracranial aneurysms

“…The Hydrogel Endovascular Aneurysm Treatment Trial (HEAT) described outcomes of 600 patients randomized to coiling with either bare platinum coils or hydrogel coated coils. 19 The incidences of major recurrences (defined as progression of RROC from 1 or 2 to 3) were 12.8% and 20.7% for the HydroCoil Embolic System (HES) and the bare platinum coils (BPCs), respectively. The incidences of major recurrences in this series was significantly smaller (5.8%).…”

Surgical Clipping Versus Endovascular Coiling in the Management of Intracranial Aneurysms

“…Despite this theoretical benefit, the Matrix and Platinum Science trial conducted by McDougall et al did not find the Matrix coils (bioactive coils) superior to the bare metal coils, though their non-inferiority was demonstrated [ 56 ]. The Hydrogel Endovascular Aneurysm Treatment (HEAT) trial was a randomized controlled trial that compared the HydroCoil Embolic System (HES, MicroVention, Inc., Aliso Viejo, CA) (contains a platinum core with integrated hydrogel) with bare platinum coils (BPC), on both ruptured and unruptured 3-14 mm aneurysms [ 57 ]. A total of 4.4% in the HES group showed recurrence, as compared to 15.4% of the BPC group, showing the superiority of HES over BPC [ 57 ].…”

Growth of unruptured aneurysms: A meta-analysis of natural history and endovascular studies

“…[27,29] Recently published studies show promising results when hydrogel coils are used. [5,26] However, the use of these bioactive coils has been a topic of great debate so far, as the long-term effects of the in ammation they induce is still unknown. [7] It is also unknown whether the in ammation which leads to growth and rupture is in uenced in any way by the in ammation induced by endovascular treatment of aneurysms.…”