Standard vs High Dose of Unfractionated Heparin in the Incidence of Radial Artery Occlusion (DEFINITION) Trial.

Radial artery occlusion (RAO) is one of the most common complications in transradial artery interventions (up to 30% of cases if specific measures are not taken to prevent it) and is related to the prothrombotic state of the patient, the scarce distal flow to the access site and the trauma caused to the artery during the procedure.

Currently worldwide, the transradial (TRA) access is the most widely used access for coronary angiography (in up to 90% of the procedures) because the transradial approach is associated with lower rates of vascular complications and event mortality (compared to the femoral access).

Although TRA access is safer, it is not free of complications, being one of the most important the RAO.

There are universal efforts to reduce RAO improving every aspects of the technique, from the type of introducer to the hemostasis time to a distal TRA, with evidence suggesting that higher doses of UFH can also decrease RAO to a greater extent. The decrease in the incidence of RAO have been proposed to be up to 2.8 times with high doses of UFH (single-center, retrospective study that compared regular not standard doses of UFH versus higher doses of UFH) although no proper prospective clinical trial have been undertaken to prove this.

The standard dose that has shown a lower rate of RAO is 5000 IU, which will be compared with 100 IU / Kg of UFH, with a randomized, prospective, double-blind design, with short-term (24-hour) follow-up with Doppler ultrasound (DUS) and its correlation with plethysmography to document RAO, and in occluded arteries, there will be a 30-day follow-up to determine the recanalization (or persistent occlusion) rates by DUS (and plethysmography). In order to address safety concerns of higher UFH doses, all the potential hemorrhagic complications will be evaluated during the study follow-up time and higher hemorrhagic risk patients are going to be excluded.