Study of biomarker profiling to unravel the intertwined pathophysiology of coronary artery disease and abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is defined as a permanent localized dilatation
of the abdominal aorta; a progressive disease with rupture as most disastrous
complication. AAA size alone does not always accurately predict the risk of
rupture. Further research is needed in order to install timely and personalized
treatment. Blood biomarkers are capable of detecting subtle changes in the
pathophysiological processes underlying AAA and can be easily measured. Use of
serial biomarker measurements may provide information on individual patterns
and may aid in AAA prognostication. Given the overlap in biological systems
involved, this may particularly apply to those blood biomarkers that have
already proven to be of value in coronary artery disease (CAD). Genetic factors
also contribute importantly to AAA. Blood biomarkers of known genetic causes of
AAA may also aid in explaining and predicting differences in clinical
manifestations of AAA like growth patterns and risk for rupture.

The primary objective is to assess the associations of (temporal patterns of)
blood biomarkers with aneurysm growth in patients with AAA, with particular
attention to biomarkers that have demonstrated prognostic value for adverse
disease outcomes in CAD and biomarkers for the main genetic pathways associated
with AAA.

This study is an observational, single center study. Patients with AAA will be
recruited through the vascular surgery outpatient clinic of Erasmus MC. The
prospective, longitudinal part of the study will include an arm with 120 AAA
watchful waiting patients and an arm with 120 AAA patients undergoing
endovascular aneurysm repair (EVAR), both with a 24-month follow-up period.
Clinical data collection and blood sampling will be conducted at baseline, at 1
month after EVAR and at 6, 12, 18 and 24 months for all patients. CT will be
conducted at baseline and 12 and 24 months, plus at 1 month in the EVAR
patients. Quality of life and depression questionnaires will be performed at
baseline, at 12 and 24 months of follow-up in all patients, and at 1 month only
in EVAR patients. Additionally, a cross-sectional study will be performed in
200 patients treated for AAA with EVAR in the past years. In these patients,
clinical data collection, blood sampling, ultrasound (including 2D and 3D
images) and CT will be performed at their next regular outpatient clinic visit.

This is an observational study that does not interfere with regular treatment.
The main burden of this study consists of extra visits to the outpatient
clinic. However, by combining the study visits with the planned outpatient
clinic visits, this will be kept to a minimum of about three times. Procedures
during the study visits include obtaining clinical data, blood sampling,
ultrasound imaging (for cross-sectional patients), periodical CT scan imaging
and periodical questionnaires. CT imaging performed as part of standard medical
care will be used for our research purposes in the EVAR patients, with at most
1 CT scan on top of usual care. In the watchful waiting patients, up to 3 CT
scans will be performed on top of usual care (which consists of
echocardiographic follow-up). To avoid complications of contrast and to limit
the additional ionizing radiation to a minimum, additional CTs performed solely
for research purposes will comprise non-contrast CT scans, and radiation
exposure will be minimized to 3.2 mSv per CT scan by optimizing equipment
settings.