C1 esterase inhibitor (C1-INH) for the off-label treatment of angiotensin-converting enzyme inhibitor induced angioedema

Introduction: Currently, C1 esterase inhibitor (C1-INH) is indicated for hereditary angioedema (HAE) but is utilized off-label for angiotensin- converting enzyme inhibitors (ACEi) induced angioedema (AAE). There is no standard of care for the treatment of AAE, however patients may receive a combination of epinephrine, corticosteroids, fresh frozen plasma (FFP), tranexamic acid (TXA), and histamine 1 and 2 receptor antagonists (H1RA, H2RA). C1-INH place is therapy is not well defined. Materials & Methods: A retrospective chart review was conducted from patients at a large academic medical center who received C1-INH for AAE between January 2012 and May 2022. Variables and outcomes of interest were receipt of alternative angioedema treatment prior to C1-INH, time of C1-INH administration, dose of C1-INH, need for intubation or surgical airway placement, duration of intubation, and hospital length of stay. Results: All patients received additional medications for angioedema prior to C1-INH administration. Steroids and H1RAs were most common. The dose of C1-INH ranged from 11.7 IU/kg to 23.2 IU/kg with an average dose of 19.3 IU/kg. Five patients required airway support with four requiring intubation (30.8%) and one requiring a surgical airway. Conclusions: This retrospective review of 13 patients showed mixed results for C1-INH to prevent intubation in AAE. Providers should consider limiting the use of C1-INH to patients who remain symptomatic after administering a combination of other therapies when there is an ongoing risk for airway compromise and adequate time for preparation, administration, and effect.