HERCULES Trial
Rijnstate at the forefront of pioneering international research into the treatment of aneurysms
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Rijnstate plays an important role in a groundbreaking trial on the treatment of abdominal aortic aneurysms. In total 300 patients will be recruited, from 20 US hospitals and 20 european hospitals.
The HERCULES trial is an investigator-driven study (collaboration of Prof. M.M.P.J. Reijnen, MD and Prof. K. Donas, MD), in collaboration with Medtronic. Rijnstate is the Sponsor of the study.
An aneurysm is defined as an enlargement of an artery of at least 1.5 times its normal diameter. Aneurysms most commonly occur in the abdominal aorta, in which case they are known as an ‘abdominal aortic aneurysm’ or AAA. More information on the widening (dilation) of the abdominal aorta (aneurysms) is available on the Dutch Heart Foundation (Hartstichting) website All about abdominal aneurysms | Dutch Heart Foundation).
Roughly 1 in 1,000 individuals will develop an AAA between the ages of 60 and 65, and this number increases with age. Studies show that the prevalence of abdominal aortic aneurysm in men is 2-13% and ±6% in women over the age of 65.
The larger the diameter of the AAA, the weaker the blood vessel wall will become. The risk of rupture of the AAA increases with its diameter and this would lead to an often lethal arterial bleeding. Both the AAA itself and surgical procedures to repair an AAA are not without risks. Once the widening in the blood vessel measures ≥55 mm in men and ≥50 mm in women, the risks of a rupture may outweigh the risks of surgery. This still depends on the anatomy of the AAA and the comorbidity of the patient. Today, many AAAs are treated through a minimally invasive procedure known as Endovascular Aneurysm Repair or EVAR. This procedure involves inserting an endoprosthesis, or stent graft, into the AAA through small incisions or puncture holes in the groin.
A healthy landing zone between the renal arteries and in both iliac arteries is needed for EVAR. The zone below the renal arteries is called the infrarenal neck. Patients can be treated inside the instructions for use of the stent graft up to a diameter of 32 mm. When larger than 28 mm, however, the neck is called a wide neck. Recently, a systematic review and meta-analysis found that a wide neck is present in approximately 27% of patients with aneurysms who are treated with an stent graft.(Laczynski 2021; PMID: 33722632; DOI: 10.1016/j.jvs.2021.02.043). A wide neck is related to an increased risk of complications over the long term. There is a risk of stent displacement (migration) as well as endoleak, i.e. leakage around the stent into the AAA. These complications can lead to pressure once more the AAA, which may necessitate another intervention. Another treatment, known as ESAR, uses specifically designed implants (EndoAnchorsTM) to attach the inserted endoprosthesis to the wall of the infrarenal neck.
For patients with an AAA and a wide neck, it is currently unknown which treatment is the best option.
The HERCULES Trial
A randomized study may answer the question if ESAR shows better outcomes than EVAR in this specific patient population. Participants will be randomly allocated into comparison groups for these two (already available) treatment options. If you want more information, you can check the website www.clinicaltrials.gov., ID of the trial is: NCT05484115.
Which patients are eligible for participation in the trial
The treating physician determines if the AAA patient has a wide neck on CT-scan imaging with contrast. If that is the case and all inclusion and exclusion criteria are met, the physician discusses participation in the HERCULES trial with the patient.
For this trial, a total of 300 participants will be recruited worldwide. Approximately twenty hospitals in Europe and approximately twenty hospitals in the US will participate. The expected time for patient inclusion is three years.
After the treatment, patients will be followed for a period of five years. The stent grafts to be used are the Endurant II/IIs stent graft system (EVAR arm) and the Endurant II/IIs stent graft system, as well as the Heli-FX EndoAnchorTM System (ESAR arm).
The primary endpoint of the trial is a composite endpoint of outcomes measured via 1-year post-treatment contrast enhanced CT-scans. The primary endpoint will be the absence of: (1) type IA endoleak (leakage around the stent graft into the AAA) and (2) migration (displacement) of the upper portion of the stent graft of ≥5 mm (as compared to the 1-month post-treatment CT scan) and (3) aneurysm sac growth of ≥5 mm (as compared to the 1-month post-treatment CT scan).
