The choice of antithrombotic regimen during TAVI and CTO PCI includes the use of
unfractionated heparin. Heparin is the preferred anticoagulant drug in these percutaneous
cardiac interventions aiming for an Activated Clotting Time (ACT) > 200sec or 250seconds
depending on the procedure. Heparin has a short half-life time and can be neutralized by
protamine.
Monitoring the use of unfractionated heparin during TAVI and PCI can be performed with
several measurements, like the ACT and aPTT. To measure ACT, an activator is mixed with whole
blood to provide a timing of haemostasis. aPTT is a plasma test in which a surface activator
is used to measure the time it takes to form a fibrin clot. In nearly every center ACT is the
preferred method because of its ease of use and the assumed reliability. ACT-guided heparin
regime during TAVI seems effective in minimizing major bleeding events.
There are limited studies focussing on the difference between ACT- and aPTT measurements. The
studies which investigated this difference are merely done in patients with continuous
heparin infusions, for example in the setting of extracorporeal membrane oxygenation(ECMO).
These studies suggest that there is a better correlation between aPTT and dosage heparin than
between ACT and heparin. Also, the correlation between ACT and aPTT seems poor.
The accuracy and correlation of ACT with a point-of-care aPTT test for monitoring the
anticoagulation effect of unfractionated heparin has so far not been done in the setting of
percutaneous interventions. TAVI requires large bore arterial access and is associated with a
relevant frequency of access site related bleeding and vascular complications. CTO procedures
often require dual arterial access and the use of different strategies with multiple wires
which increases the prevalence of vascular complications, including pericardial effusion.
Precise knowledge of actual anticoagulation status during an invasive procedure and at the
time of access site closure may affect the incidence of TAVI and CTO PCI related bleeding
complications.
Therefore, the aim of the present study is to evaluate which point-of-care test (ACT or aPTT)
gives the best correlation with the coagulation status in patients during TAVI and CTO PCI.