Increased thrombogenicity in patients with atherosclerosis of the peripheral arteries of the lower extremities: a case-control study.

Intermittent claudication is the most important symptomatic manifestation of
peripheral arterial disease (PAD) and is associated with a significant
morbidity and mortality. The pathophysiological processes involved in the
occurrence of complications in PAD are: thrombosis and atherogenesis.
Exposure of blood to the thrombogenic surface of the ruptured atherosclerotic
plaque, is not fully explaining the complications.
In the literature evidence can be found for the role of Virchow*s triad in
thrombogenesis, and the generation and course of PAD and related complications.
Components of Virchow*s triad are: hypercoagulability, hemodynamic changes and
endothelial injury/dysfunction.
PAD patients seem to adhere to these three components, and are thought to have
a 'prothrombotic' or 'hyper coagulable status'. The Thrombogram* is a
relatively new method to evaluate a patient*s coagulable state by measuring
thrombin generation in time. It is a modern *over-all* physiological test which
is capable to report the function of the haemostatic-thrombotic system. The
Maastricht flow-chamber assay is measuring thrombocyte function in a full-blood
sample. Blood will be forced to flow along different thrombogenic surfaces at
different velocities. Comparing analyses of thrombocyte activation will be
carried out by using a well-plate based cytrometric assay. Thromboelastometry
(ROTEM) with added tPA can give better insights in the build-up and break-down
of a blood clot. This viscoelastometric method, carried out in full-blood,
providing information about interactions between different coagulation factors,
inhibitors of coagulation and cellular components, during the coagulation and
fibrinolytic phase, is measured during two hours. Because whole blood is used
in this assay, it is more comparable to the in vivo situation, except for the
effects of the endothelium. Measurement of Micro-RNA*s; which possibly are
involved in the pathological process of peripheral atherosclerosis.

In PAD patients, the coagulation status of patients with a vascular
complication, will be compared (based on test results of the Thrombogram*,
Thromboelastometry and MiRNA*s) to the coagulation status of PAD patients
without a vascular complication and to a healthy control group. Both groups
will be sex and age matched. Possible differences in thrombocyte function can
be investigated under flow, by using the flow chamber assay. The final goal is
to develop insight in these relationships and see if PAD patients with a
vascular complication (within 1 year after diagnosis), have a different
(increased) coagulation status. For this reason they are possibly at risk for
progression of the atherosclerotic process and occurrence of further vascular
events.

A mono-centre observational hypothesis generating study, executed as a
case-control study. 80 persons will be included, of which 40 PAD patients and
40 healthy controls. The PAD patients are divided into two groups: 20 patients
with (cases) and 20 patients without (controls) a vascular complication within
1 year after the diagnosis. All PAD patients will be included from the PAD
study (Hypercoagulability and Atherosclerosis-based Vascular Complications in
Patients with Peripheral Arterial Disease of The Lower Extremities (MEC
07-02-088)). Cases will be patients from the PAD study, who reached one or more
of the following end-points within 1 year of follow-up:

- *vascular load* cerebrovascular
o ischemic TIA
o ischemic CVA
- *vascular load* cardiovascular
o the novo unstable angina
o myocardial infarction
o revascularisation
- *vascular load* abdomen
o mesenteric ischemia
o renal arterial stenosis + hypertension
- *vascular load* peripheral
o increased symptoms of ischemia + Δ Ankle-brachial-index (ABI) >= 0.1
o increased symptoms of ischemia + intervention

PAD patients will be included as *case* if they are diagnosed with or operated
because of one or more *vascular load* areas mentioned above.
PAD patients will be included as *controls* if they didn*t reach one of the
end-points within 1 year of follow-up in the PAD study.
Forty healthy volunteers (age and sex matched) will be included. These persons
will be asked to come to the hospitals once and help us with giving possibility
to compare the results with healthy people as well.

The non-significant burden and risk to the patients, utilizing the least
invasive methods ( vein puncture only ) in the study, and the great social and
scientific relevance of it, makes it of a great importance. The results of the
following trial could help medical doctors improve their behaviour with regard
to this world-wide spreading disease.