Rapid Aspirin Challenge in Patients with Aspirin Allergy and Acute Coronary Syndromes

Aspirin hypersensitivity: a practical guide for cardiologists

Aspirin has been known for a long time and currently stays as a cornerstone of antithrombotic therapy in cardiovascular disease. In patients with either acute or chronic coronary syndromes undergoing percutaneous coronary intervention aspirin is mandatory in a dual antiplatelet therapy regimen for prevention of stent thrombosis and/or new ischaemic events. Aspirin is also currently a first-option antithrombotic therapy after an aortic prosthetic valve replacement and is occasionally required in addition to oral anticoagulants after implantation of a mechanical valve. Presumed or demonstrated aspirin hypersensitivity is a main clinical problem, limiting the use of a life-saving medication. In the general population, aspirin hypersensitivity has a prevalence of 0.6%-2.5% and has a plethora of clinical presentations, ranging from aspirin-exacerbated respiratory disease to anaphylaxis. Although infrequent, when encountered in clinical practice aspirin hypersensitivity poses for cardiologists a clinical dilemma, which should never be trivialized, avoiding-as much as possible-omission of the drug. We here review the epidemiology of aspirin hypersensitivity, provide an outline of pathophysiological mechanisms and clinical presentations, and review management options, starting from a characterization of true aspirin allergy-in contrast to intolerance-to suggestion of desensitization protocols.

How to Define and Manage Low-Risk Drug Allergy Labels

Risk stratification in drug allergy implies that specific risk categories (eg, low, moderate, and high) classify historical drug hypersensitivity reactions. These risk categories can be based on reaction phenotypic characteristics, the timing of the reaction and evaluation, the required reaction management, and individual characteristics. Although a multitude of frameworks have been described in the literature, particularly for penicillin allergy labels, there has yet to be a global consensus, and approaches continue to vary between allergy centers. Immune-mediated drug allergies can sometimes be confirmed using skin testing, but a negative drug challenge is required to demonstrate tolerance and remove the allergy from the electronic health record ("delabel" the allergy). Even for quintessential IgE-mediated drug allergy, penicillin allergy, recent data reveal that a direct oral challenge, without prior skin testing, is an appropriate diagnostic strategy in those who are considered low-risk. Drug allergy pathogenesis and clinical manifestations may vary depending on the culprit drug, and as such, the optimal approach should be based on risk stratification that considers individual patient and reaction characteristics, the likely hypersensitivity reaction phenotype, the drug class, and the patient's clinical needs. This article will describe low-risk drug allergy labels, focusing on β-lactam and sulfonamide antibiotics, nonsteroidal anti-inflammatory drugs, iodinated contrast media, and common chemotherapeutics. This review will also address practical management approaches using currently available risk stratification and clinical decision tools.

Coronary Artery Disease and Aspirin Intolerance: Background and Insights on Current Management

Aspirin is one of the most widely used medications across the global healthcare system and is the foundation in treating ischemic heart disease, as well as secondary prevention for ischemic and valvular heart disease. Challenges arise in treating patients with cardiovascular disease who have concomitant aspirin intolerance. Through an extensive review of the literature, we provide a comprehensive background on the pharmacology of aspirin, the mechanisms behind aspirin intolerance, the importance of aspirin in cardiovascular disease, and the management of aspirin intolerance in both acute coronary syndrome and stable coronary artery disease. Our review includes a multidisciplinary approach from the internist, allergist/immunologist, and cardiologist when evaluating this important patient population.

Cilostazol combined with P2Y12 receptor inhibitors: A substitute antiplatelet regimen for aspirin-intolerant patients undergoing percutaneous coronary stent implantation

Background

Cilostazol combined with P2Y₁₂ receptor inhibitor has been used as a substitute regimen for aspirin‐intolerant patients undergoing percutaneous coronary stent implantation on a small scale. Its exact impact on platelet functions and clinical benefits of aspirin‐intolerant patients is unknown.

Hypothesis

Cilostazol combined with P2Y₁₂ receptor inhibitors could be used as a substitute antiplatelet regimen for aspirin‐intolerant patients undergoing percutaneous coronary stent implantation.

Methods

In this multicenter prospective cohort trial, patients undergoing elective percutaneous coronary stent implantation were assigned to the cilostazol group (cilostazol plus P2Y₁₂ receptor inhibitors), based on aspirin intolerance criteria, or the aspirin group (aspirin plus P2Y₁₂ receptor inhibitors). Platelet PAC‐1, CD62p, and vasodilator‐stimulated phosphoprotein phosphorylation (VASP‐P) were detected by flow cytometry. The primary endpoints were major adverse cardiovascular and cerebrovascular events (MACCE) including all‐cause death, acute myocardial infarction, emerging arrhythmia, nonfatal stroke, and heart failure. The secondary endpoints were the Bleeding Academic Research Consortium (BARC) bleeding events.

Results

One hundred and fifty‐four aspirin‐intolerant percutaneous coronary stent implantation patients and 154 matched aspirin‐tolerant patients from a total of 2059 percutaneous coronary stent implantation patients were enrolled. The relative activation level of PAC‐1, CD62p, and platelet reaction index reflected by the VASP‐P test were similar in the two groups (p > .05). After 12 months of follow‐up, the incidence of all‐cause death was 1.9% in the cilostazol group and 1.3% in the aspirin group (risk ratio [RR], 1.500; 95% confidence interval [CI], 0.254–8.852; p = 1.000); the incidence of acute myocardial infarction was 0.6% in the cilostazol group and 1.3% in the aspirin group (RR, 0.500; 95% CI, 0.046–5.457; p = 1.000). No significant difference was seen in other MACCE events, or in any types of BARC bleeding events.

Conclusions

Cilostazol combined with P2Y₁₂ inhibitors was not inferior to aspirin‐based standard therapy and could be used as a reasonable substitute antiplatelet regimen for aspirin‐intolerant patients undergoing percutaneous coronary stent implantation, but again with limitations, which required a larger sample and longer follow‐up to confirm its efficacy.

The efficacy and safety of cilostazol as an alternative to aspirin in Chinese patients with aspirin intolerance after coronary stent implantation: a combined clinical study and computational system pharmacology analysis

Dual antiplatelet therapy (DAT) with aspirin and clopidogrel is the standard regimen to achieve rapid platelet inhibition and prevent thrombotic events. Currently, little information is available regarding alternative antiplatelet therapy in patients with an allergy or intolerance to aspirin. Although cilostazol is already a common alternative to aspirin in clinical practice in China, its efficacy and safety remain to be determined. We retrospectively analyzed 613 Chinese patients who had undergone primary percutaneous coronary intervention (PCI). Among them, 405 patients received standard DAT (aspirin plus clopidogrel) and 205 patients were identified with intolerance to aspirin and received alternative DAT (cilostazol plus clopidogrel). There were no significant differences between the two groups in their baseline clinical characteristics. The main outcomes of the study included major adverse cardiac events (MACEs) and bleeding events during 12 months of follow-up. The MACEs endpoint was reached in 10 of 205 patients treated with cilostazol (4.9%) and in 34 of 408 patients treated with aspirin (8.3%). No statistically significant difference was observed in MACEs between the two groups. However, patients in the cilostazol group had less restenosis than did patients in the aspirin group (1.5% vs 4.9%, P=0.035). The occurrence of bleeding events tended to be lower in the cilostazol group (0.49% vs 2.7%, P=0.063). These clinical observations were further analyzed using network system pharmacology analysis, and the outcomes were consistent with clinical observations and preclinical data reports. We conclude that in Chinese patients with aspirin intolerance undergoing coronary stent implantation, the combination of clopidogrel with cilostazol may be an efficacious and safe alternative to the standard DAT regimen.