(567) Evaluation of the Efficacy and Safety of Alteplase for the Treatment of Frostbite Injuries

Introduction: Frostbite injury results in significant tissue damage due to extracellular ice crystal formation and micro-emboli leading to tissue ischemia. Beyond rapid rewarming, early alteplase may improve tissue salvage rates. Our institution previously reported the safe and effective use of remote thrombolytic administration prior to transfer. Nevertheless, significant concern remains regarding this practice. The objective of this study was to assess the efficacy and safety of alteplase for the treatment of severe frostbite injuries in a follow-up cohort.

Methods: This retrospective cohort included adult patients who received alteplase for second and third degree frostbite within 24 hours of rewarming over a two-year period. Alteplase followed by enoxaparin anticoagulation was driven by an institutional policy. Hennepin scores (baseline and discharge) and triple phase bone scans were completed. The primary outcome was the ratio of digits salvaged vs. at risk. Secondary outcomes included change in Hennepin scores, perfusion outcomes on bone scan, and bleeding events according to GUSTO criteria.

Results: A total of 28 patients were included, the majority male (89.3%) with median (IQR) age, Hennepin score, and percent body surface affected of 34 years (25, 30), 14 (3, 20), and 0.75% (0.28, 2.13), respectively. A total of 216 digits were at risk with third degree injuries in 73 digits (33.9%). Following alteplase, 183 (84.7%) total digits and 46 (63%) third degree digits were salvaged. Hennepin scores (n=27) significantly decreased following alteplase to a median (IQR) of 2.5 (0.8, 10.1), P=0.0003. Serial bone scans were completed in 18 patients. The initial scan occurred post-alteplase in 15. Repeat bone scans on day 3 were unchanged, improved, or worsened in 12 (66.7%), 5 (27.8%), and 1 (5.6%), respectively. Moderate bleeding occurred in 1 (3.6%) patient which required transfusion without hemodynamic compromise.

Conclusions: Alteplase use was associated with a high rate of digits salvaged and a significant reduction in Hennepin scores without severe adverse events. This remains consistent with previously reported outcomes assessing efficacy and safety of alteplase for frostbite. Larger comparative studies are required to assess the relative risk-benefit ratio of alteplase vs. other treatment options.