Rapid Desensitization to Overcome Contrast Allergy Prior to Urgent Coronary Angiography

Research progress on desensitization of hypersensitivity reaction to iodinated contrast media

Desensitization therapy for iodinated contrast media (ICM) aims to induce drug tolerance in patients with a history of severe allergic reactions to ICM in a short time. Currently, there is no widely accepted consensus on inducing desensitization to avoid severe allergic responses to ICM. The clinically successful cases have shown that prophylactic use of antihistamines and glucocorticoids can increase the desensitization effect; repeatedly desensitizing and gradually increasing the dose can be conducive to establishing better tolerance to ICM. Most desensitization effects, including stress resistance, can endure 24-48 h. The mechanisms of desensitization therapy remain unclear, the initial dose, administration interval and dose gradient are largely based on clinical experiences and the reaction of patients. This article reviews the current research progress on ICM-related allergies, desensitization methods and related mechanisms, as well as the benefits and hazards of desensitization, to provide a reference for desensitization treatment of hypersensitivity to ICM .

Radiocontrast Media Hypersensitivity Reactions in Children

Hypersensitivity reactions to radiocontrast media seem to be rare in children. Furthermore, the use of radiocontrast media in children remains quite safe in terms of the severity of reactions. Since pediatric guidelines are lacking, the diagnostic workup employed in adults could be adapted to children, taking into account that results have not yet been validated in this age group. Specific protocols for risk stratification and management of severe reactions have been proposed so far.

Zero-contrast percutaneous coronary intervention for chronic total occlusions guided by intravascular ultrasound with ChromaFlo mode: a case report

Background

Contrast agent allergy may result in severe adverse events that prevent the use of percutaneous coronary intervention (PCI) in some patients, especially for those with complex lesions.

Case summary

We describe a 59-year-old man who presented with the multi-vessel disease and suffered from contrast allergy. The patient refused to have coronary artery bypass grafting surgery, thus two-stage PCI procedures without iodinated contrast media were performed after a detailed discussion with the heart team, including a chronic total occlusion (CTO) lesion in the proximal left anterior descending artery. The intravascular ultrasound (IVUS) was used for finding the entry point of the proximal fibre cap, and assessing the lesion, thereby marking the positions of the proximal and distal edges of the stent. After PCI, stent expansion and subtle edge dissection or incomplete apposition were confirmed by IVUS and ChromaFlo imaging. Zero-contrast PCI was done successfully without any complication.

Discussion

This case report illustrates the feasibility and safety of performing CTO-PCI without contrast agent in carefully and well prepared selected patients.

Successful Coronary Angiography Following Rapid Intravenous Desensitization for Refractory Contrast Allergy

Most allergic reactions to radiocontrast media can be managed with a pretreatment protocol of steroids and antihistamines. However, in rare circumstances, patients can have severe allergic symptoms despite pretreatment. In this case, we highlight the use of a novel desensitization protocol in a patient with a severe breakthrough contrast allergy and unstable angina that allowed for successful percutaneous coronary intervention. The protocol was well tolerated, feasible, and might allow other patients with similar allergies to undergo angiography and imaging studies successfully that require the use of radiocontrast media.

Drug hypersensitivity reactions in Asia: regional issues and challenges

There are geographical, regional, and ethnic differences in the phenotypes and endotypes of patients with drug hypersensitivity reactions (DHRs) in different parts of the world. In Asia, aspects of drug hypersensitivity of regional importance include IgE-mediated allergies and T-cell-mediated reactions, including severe cutaneous adverse reactions (SCARs), to beta-lactam antibiotics, antituberculous drugs, nonsteroidal anti-inflammatory drugs (NSAIDs) and radiocontrast agents. Delabeling of low-risk penicillin allergy using direct oral provocation tests without skin tests have been found to be useful where the drug plausibility of the index reaction is low. Genetic risk associations of relevance to Asia include human leucocyte antigen (HLA)-B*1502 with carbamazepine SCAR, and HLA-B*5801 with allopurinol SCAR in some Asian ethnic groups. There remains a lack of safe and accurate diagnostic tests for antituberculous drug allergy, other than relatively high-risk desensitization regimes to first-line antituberculous therapy. NSAID hypersensitivity is common among both adults and children in Asia, with regional differences in phenotype especially among adults. Low dose aspirin desensitization is an important therapeutic modality in individuals with cross-reactive NSAID hypersensitivity and coronary artery disease following percutaneous coronary intervention. Skin testing allows patients with radiocontrast media hypersensitivity to confirm the suspected agent and test for alternatives, especially when contrasted scans are needed for future monitoring of disease relapse or progression, especially cancers.

Additional Value of Early Repolarization Pattern in Prediction of Obstructive Coronary Artery Disease as Assessed by Coronary Angiography

Recent reports show that an early repolarization pattern (ERP) is associated with a higher incidence of sudden cardiac death in patients with obstructive coronary artery disease (CAD). Sporadic case studies have pointed out that ERP might be related to obstructive CAD.In consecutive patients who had undergone coronary angiography, we investigated the relationship between ERP and obstructive CAD by evaluating its association with coronary artery stenosis.The study population consisted of 3785 patients (59.9% men; mean age 63.1 years) with or without obstructive CAD. Adjusting for major cardiovascular risk factors, ERP was significantly associated with obstructive CAD (adjusted odds ratio (OR): 2.24 [95% CI 1.70-2.95]) with an incremental predictive value (ROC AUC 0.76 versus 0.71, P = 0.02; NRI 55.3%, P < 0.001; IDI = 0.05, P = 0.008), specifically in subjects with low risk and intermediate risk. ERP also significantly improved the predictive value for multi-vessel disease (AUC: 0.77 versus 0.72, P = 0.02 for two-vessel disease; 0.79 versus 0.73, P = 0.04 for three-vessel disease). ERP was consistently associated with stenoses of 3 main coronary arteries.ERP is associated with significant increased risk for obstructive CAD.Further studies are warranted to confirm our results and to elucidate the specific pathogenic mechanisms.

Radiologic Contrast Media Desensitization for Delayed Cardiac Catheterization

This protocol for rapid desensitization to intravenous radiographic contrast material (RCM) improves the strategy first reported by Uppal et al. Desensitization is a validated preventative measure for medical emergencies, such as cardiac catheterization, when patients present with histories of anaphylactoid reactions to the allergen of concern. The patient required another catheterization that was modified to repeat the final dosage of 320 mg/mL of Visipaque®, accommodating cardiac catheterization postponement, contrary to readministration of doses 4 (0.625 mg/mL) and 8 (10 mg/mL) as reported in Uppal et al. Our risk score calculations suggested that the patient was at low risk of contrast-induced nephropathy (CIN) that did not necessitate reduced dosage. No complications were reported following catheterization. We propose repetition of the final RCM dosage as a more effective and efficient desensitization strategy, as long as the scoring system does not indicate high risk for CIN.