Impact of the whole activated clotting time during Impella support on short-term prognosis

Impella (Abiomed, Danvers, MA, USA) is a percutaneous trans-catheter left ventricular assist device. Anticoagulant therapy targeting whole activated clotting time (ACT) between 160 and 180 s is recommended to prevent pump thrombosis during support. However, we sometimes experience fatal bleeding despite achieving the target ACT range. Consecutive patients who received Impella support in our institute between March 2018 and October 2020 were included in this retrospective study. The association between the averaged ACT levels during the Impella support and 30-day mortality was investigated. A total of 36 patients (71 years old, 61% males) were included. Most of the patients were managed within the recommended therapeutic range of ACT, and the average ACT level was 162 s. The higher ACT group (> 168 s) had older age, smaller body mass index, and higher serum creatinine compared with the lower ACT group (p < 0.05 for all). A higher ACT level was an independent risk factor of 30-day mortality with an adjusted hazard ratio of 1.085 (95% confidence interval 1.037-1.154) with a cut-off level of 168 s. There were only two thromboembolic events. Patients managed with higher ACT levels had a higher risk of 30-day mortality during Impella support. A low-dose heparin purge solution might be recommended in patients with high-risk for bleeding events.