Clinical Efficacy of 13-Hour Premedication Regimen for Contrast Allergy before Percutaneous Coronary Intervention

Background
The purpose of this study was to determine the rate of allergic or anaphylactoid reactions after a 13-hour premedication regimen before percutaneous coronary intervention (PCI) among patients with a prior record of allergy to iodinated contrast material (ICM).

Methods
A retrospective observational study was done to identify high-risk individuals with ICM allergy who underwent PCI at Geisinger Health System between January 2005, and May 2018. We queried the Geisinger CathPCI Registry records and Geisinger electronic health records (EHR) to identify all patients who had a prior record of ICM allergy and underwent PCI during the study period. Patients were excluded if prednisone and diphenhydramine were not given at least 13 hours before the PCI, which included three doses of prednisone 50 mg (13, 7, and 1 hour before PCI) and diphenhydramine 50 mg 1 hour before PCI. We manually queried EHR to evaluate the severity of ICM allergy and subsequent breakthrough reaction, which was defined as allergic-like reactions to ICM that occurred despite premedication. Based on the symptoms, we defined prior ICM allergic and breakthrough reactions as mild, moderate, or severe.

Results
A total of 15,712 patients underwent PCI of which 182 patients with confirmed ICM allergy were included in this study. Mean age was 67.5 years, and 56% were male. Two patients (1.1%) underwent emergency PCI, 23 patients (12.8%) had elective PCI, and 155 patients (86.1%) underwent urgent PCI. Five patients (3%) presented with atypical chest pain, 18 (10%) presented with stable angina, 97 (53%) presented with unstable angina, 60 (33%) presented with NSTEMI and two patients presented with STEMI. Prior allergic response to ICM was mild in 64 patients (35%) moderate in 14 (8%), and severe in 51 (28%). During or after PCI, breakthrough reactions occurred in 6 patients (3.2%). Only one patient experienced severe breakthrough reactions, in others these were relatively mild.

Conclusions
Of patients with previous ICM reactions pretreated with 13-hour steroid based regimen before PCI, only 3.2% had a breakthrough reaction while severe breakthrough reactions were rare. The regimen is effective in preventing recurrence of allergic reactions.