The imprecision of measuring activated clotting time (ACT) from the guiding catheter during percutaneous coronary interventions

Background: Finding the balance between the reduction in ischemic events and bleeding complications is crucial for the success of percutaneous coronary intervention (PCI). The activated clotting time (ACT) is used routinely worldwide to monitor and titrate anticoagulation therapy with unfractionated heparin (UFH) during the procedure.

Objectives: We aimed to test the accuracy of ACT measurements from the guiding catheter compared to the arterial access sheath.

Methods: Patients undergoing PCI with UFH therapy were prospectively enrolled. Blood samples were drawn from the coronary guide catheter and the arterial access sheath. ACT values were determined in the same ACT machine, and potential interactions with clinical variables were analyzed.

Results: The study included 331 patients with post PCI ACT measurements. The mean ACT value of the catheter samples was statistically higher than the arterial access sample [294 ± 77 s Vs. 250 ± 60 s, p < 0.001]. The mean difference between the guiding catheter and the arterial line sheath samples was 43 ± 27 s (P < 0.001). We found that in 101/331 [30 %] patients the ACT from the guiding catheter was above 250 s, while from the access sheath it was below 250 s. Notably, in 40/331 [12 %] the ACT from the guiding catheter was above 200 s, while from the access sheath it was below 200 s.

Conclusions: Large proportion of patient may be considered to have therapeutic ACT if measured from guide catheter during PCI, while the corresponding ACT from arterial sheath is subtherapeutic. This difference may have clinical and safety significance.