Platelet-Based Dose-Adjusted Low Molecular Weight Heparin Treatment Is Efficacious and Safe in Newly Diagnosed Acute Leukemia Patients with Catheter-Related Thrombosis

Introduction: Catheter-related thrombosis (CRT) is a major complication in patients with acute leukemia. Severe thrombocytopenia related to either the concomitant disease or therapy underscores the challenge of CRT management, resulting in the use of suboptimal anticoagulation, potentially leading to high rates of short-term complications, including recurrent thromboembolism and hemorrhage. Due to the paucity of data regarding the impact of reduced-dose anticoagulation on this clinical setting, the current study aimed to assess the safety and efficacy of this treatment approach to CRT management in this challenging patient population.

Methods: In this retrospective, case-control study, all adult (age ≥18 years) acute leukemia patients, who had arrived at the Rambam Health Care Campus (RHCC, Haifa, Israel) between 1.11.2004-30.6.2022 to receive anti-leukemia therapy via a peripherally inserted central catheter (PICC) line were screened. The inclusion criteria were: patients with acute myeloid, promyelocytic and lymphoid leukemia (AML, APL, and ALL, respectively) and CRT confirmed by Doppler ultrasound within 3 months of leukemia diagnosis. Patients were divided into full- (i.e., 1 mg/kg bid) vs. partial-dose low molecular weight heparin (LMWH) groups. The LMWH dose was based on the platelet count with a cutoff of 50K/L, distinguishing between the selected doses.

Primary endpoints: A record of venous thromboembolism (VTE; including pulmonary embolism (PE), deep vein thrombosis (DVT), and catheter-related thrombosis (CRT) recurrence within 12 months as well as a major hemorrhage (including intracranial, retinal and gastrointestinal hemorrhage) within 6 months. Secondary endpoints: blood product requirement (unit/day) before and after the CRT diagnosis (from leukemia diagnosis till CRT identification and 90 days or death (if prior) from the event, respectively) assessed in a self-controlled case series manner. Data were collected from the hospital electronic medical records. Chi-square and paired samples Wilcoxon tests were utilized for statistical analysis.

Results: Overall,195 patients [aged 54±15 years; 103 (53%) males], diagnosed with CRT were included. The most frequent leukemia diagnosis was AML (n=149; 76%), with ALL and APL established in 23 (12%) patients each. CRT was diagnosed in the left upper limb in 136 (70%) patients, with 99 (46%) patients suffering from DVT. Eighty-eight (45%) patients were treated with full-dose LMWH.

Recurrent VTE was identified in 11(12.5%) patients treated with full-dose LMWH vs. 9 (8.4%) receiving partial-dose LMWH (p-value 0.484), while major hemorrhage was diagnosed in 12 (13.6%) patients from the former group vs. 14 (13.0%) patients from the latter group (table 1). Similar results were documented upon stratification to deep vs. superficial CRT, and the leukemia type.

The packed red blood cell (RBC) administration rate was lower in the post-CRT phase (0.12 units/day, IQR 0.06-0.20) compared to the pre-CRT phase (0.20 units/day, IQR 0-0.36; p-value <0.0001). Platelet utilization rates were similar in both the pre-CRT and post-CRT phases (0.05 units/day, IQR 0-0.24 and 0.06 units/day, IQR 0.01-0.16, respectively; p-value 0.126). Comparable results were observed in both full and partial-dose LMWH groups.

Conclusion: LMWH dose adjustment based on platelet counts, in newly diagnosed acute leukemia patients with CRT, is not associated with higher rates of VTE recurrence. Moreover, this strategy does not result in major hemorrhagic complications even in patients with severe thrombocytopenia. Notably, RBC infusion requirements were lower in the post-CRT diagnosis phase, while platelet transfusion was similar during the pre- and post-CRT phases. This analysis, including a large number of patients, demonstrates that the adjusted therapy is safe and efficient in this challenging clinical scenario.