HAE with Normal C1-INH with Inconsistent Response to C1 Esterase Inhibitor Infusion but Reliably Responsive to Icatibant

Rationale: Hereditary angioedema (HAE) with normal C1-esterase inhibitor (C1-INH) is subdivided into factor XII mutation or of unknown origin (U-HAE). The diagnosis is based on recurrent edema (eg skin swellings, tongue swelling), family history, and normal C1-INH. U-HAE is presumed when factor XII mutation is absent. Here we present a 65 year old male with suspected U-HAE, who has a 30-year history of recurrent upper airway swelling, family history, and normal C1-INH. He initially responded to empiric C1-INH. However, he seemed to have developed resistance to C1-INH, requiring rescue therapy with icatibant.

Methods: A log method was used to collect information on attack intensity, anatomical location, number of doses, onset of relief, time until complete resolution. Hospital records and patient-reports were collected for each treatment received through the ED. 

Results: Initially the patient responded to C1-INH treatment. Within the first year, 2 attacks required treatment with multiple doses of C1-INH to achieve symptoms resolution. By February 2015, despite multiple C1-INH doses, the patient was intubated and admitted to ICU for tongue swelling with throat involvement, which resolved slowly over 4 days. In April 2015, icatibant was used for treatment in the ED when on tongue swelling occurred because he was unresponsive to C1-INH. Swelling began to subside within 1 hour of the icatibant administration. Since then, the patient has had many documented swellings that have not responded to C1 but have responded to icatibant.    

Conclusions: Icatibant can be an effective treatment for suspected U-HAE when treatment response with intravenous C1 esterase inhibitor is inadequate.