Aspirin Allergy Desensitization Possible for Acute Coronary Syndrome Patients

The American College of Cardiology and American Heart Association recommend low-dose aspirin for secondary prevention of coronary artery disease, but patients with aspirin allergies may not be able to take advantage of this prevention tactic.

Patients who have aspirin allergies usually take other blood thinners that are more costly and sometimes less effective.

However, a new study reports that withholding aspirin from acute coronary syndrome patients who report aspirin allergies may unnecessarily deprive these patients of a safe, affordable preventive option. This study, which was published in the January 2016 issue of Current Allergy and Asthma Reports, shows that rapid aspirin challenge is actually safe and successful in acute coronary syndrome patients with aspirin allergies.

A recent review showed that 1.5% of patients with coronary artery disease had possible aspirin allergies. More than 75% of these patients did not take any platelet inhibitor, and 1 in 6 took clopidogrel instead.

Only 4 patients (of 9565 total) were referred to allergists, and all 4 were safely desensitized.

The researchers differentiated between aspirin dose-related intolerances that do not call for desensitization (eg, dyspepsia, gastric ulcers, and gastrointestinal bleeding) and true aspirin allergy.

Hypersensitivity reactions can be driven by COX-1 inhibition—a nonsteroidal anti-inflammatory drug (NSAID) class effect—or an immunoglobulin E (IgE) reaction to aspirin alone. Aspirin is structurally distinct from other NSAIDs and rarely causes IgE reactions. Even the study authors said they were not aware of any documented aspirin-specific IgE-related anaphylaxis reactions.

In their study, the researchers desensitized allergic patients with aspirin-reactive airway disease in several steps.

First, they administered montelukast (Singulair)—a combination inhaled corticosteroid/long-acting bronchodilator—and systemic corticosteroids. They had rescue epinephrine ready in case of emergency.

Next, they administered 40.5 mg of aspirin and monitored the patient for 90 minutes, followed by the other half-tablet. If allergy symptoms occurred, they gave antihistamines, intranasal oxymetazoline, or nebulized bronchodilators prior to continuing the study protocol.

The study authors stressed that desensitization should be attempted before an urgent indication occurs, and the appropriate clinician to conduct the procedure is an allergist. In addition, aspirin re-challenge should not be attempted if it is associated with Stevens-Johnson syndrome, toxic epidermal necrolysis, drug rash with eosinophilia and systemic symptoms, serum sickness, or allergic interstitial nephritis.

Hemodynamically unstable patients should be stabilized before desensitization. Patients with a history of urticaria are less likely to be successfully desensitized, the researchers noted.