Initial characteristics and follow-up of patients with a diagnosis of angiotensin-converting enzyme inhibitor induced angioedema.

Background: A differential diagnosis between angiotensin-converting enzyme inhibitor (ACEi) angioedema (AE) and histaminergic AE (hAE) might be challenging. Follow-up data may help discriminate these conditions but are scarcely reported. Objective: To report on the follow-up of patients with suspected ACEi-AE and to describe the baseline characteristics of AE attacks in patients with a diagnosis of ACEi-AE after follow-up. Methods: Sixty-four patients with suspected ACEi-AE (i.e., with exposure to ACEi before the first attack, no urticaria associated, and normal C1-inhibitor levels) and at least one follow-up visit were included. Data were retrospectively collected at baseline and during the follow-up. Results: After the follow-up, the diagnosis of ACEi-AE was probable in only 30 patients. The remaining patients were reclassified as having probable hAE (21 patients) or undetermined-mechanism AE (13 patients). Patients with ACEi-AE were mostly men (61%), with a median age of 64 years (interquartile range [IQR] ±17 years), with a highly variable delay from ACEi introduction (median: 23 months; interquartile range: 103 months). Attacks preferentially involved lips (50%), tongue (47%), and throat (30%). Interestingly, patients with probable ACEi-AE after a follow-up also frequently presented with a history of allergy and atopic conditions (20%), attacks with preferential evening onset (25%), and spontaneous resolution in < 24 hours (26%), which are usually considered as suggestive of hAE. ACEi-AE attacks responded to icatibant in 79% of the patients. Conclusion: Patients with probable ACEi-AE were mostly men with facial involvement. A third of the patients with an initial suspected diagnosis of ACEi-AE had a final diagnosis of probable hAE. Although a follow-up of all patients should be a standard of care, it is critical to the correct diagnosis in the case of suspected bradykinin-associated AE, which may actually be due to histamine.