Correlation Between Activated Clotting Time and Activated Partial Thromboplastin Time During Endovascular Treatment of Cerebral Aneurysms

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Purpose: Endovascular treatment (EVT) of intracranial aneurysms (IA) requires a continuous anticoagulation to avoid thromboembolic complications. In order to monitor the anticoagulation, different tests may be used including the activated clotting time (ACT) and the activated partial thromboplastin time (APTT). The aim of this study was to compare ACT and APTT for the monitoring of the anticoagulation during EVT of IA. Methods: Patients referred for EVT of an IA were included. After induction, baseline ACT and APTT were recorded, followed by a bolus infusion of unfractionated heparin (50 UI.kg–1). The same tests were controlled five minutes later with the purpose of doubling the baseline ACT value. Correlation and agreement between both tests were evaluated for the percentage of change after the bolus. Multiple linear regressions were also calculated in order to show confounding factors. Complications and outcomes were also recorded. Results: 45 patients were checked for enrolment and 24 were included for analysis. Mean (SD) % variation for APTT was 432.1 (75.7) and 60.6 (23.0) for ACT with p < 0.0001. With the Bland-Altman method, value of Bias (SD) is 372 (86) with 95% limits of agreement range from 203 to 540. Pearson correlation for % variation shows r (95% CI) = –0.23 (–0.58 to 0.19) with p = 0.29 and R square = 0.05. 100% of the APTT values could be defined as excessive anticoagulation by opposition of the 8% obtained with ACT. Conclusions: This prospective observational study shows that ACT test is not well correlated with APTT and leads to a systematic excessive coagulation during EVT of IA.