Dyspnea and Reversibility of Antiplatelet Agents: Ticagrelor, Elinogrel, Cangrelor, and Beyond

CONTEXT: Oral reversible platelet P2Y12 receptor inhibitors (ticagrelor and elinogrel) cause double-digit rates of dyspnea, while irreversible oral antiplatelet drugs (aspirin, ticlopidoine, clopidogrel, and prasugrel) or intravenous glycoprotein IIb/IIIa inhibitors (abciximab, eptifibatide, or tirofiban) do not increase the incidence of dyspnea in randomized trials. Dyspnea after oral reversible antiplatelet agents remains unexplained. A transfusion-related acute lung injury (TRALI) hypothesis has been proposed. The dyspnea risks after cangrelor, an intravenous reversible antiplatelet agent, are not well defined but may offer a universal mechanism linking TRALI, dyspnea, and reversible platelet inhibition. OBJECTIVE: We analyzed safety data from recent head-to-head randomized trials with reversible antiplatelet agents (ticagrelor, elinogrel, and cangrelor) compared to irreversible (clopidogrel/placebo) comparators. RESULTS: All three reversible antiplatelet agents cause excess dyspnea. In contrast to the high double-digit rates after oral ticagrelor or elinogrel, the dyspnea risks after intravenous cangrelor were smaller (<2%) but still consistently and significantly higher than in the corresponding control arms. CONCLUSIONS: The clinical utility of reversible antiplatelet strategies has been challenged. Despite a potential advantage of fewer bleeding events during heart surgery, reversible antiplatelet agents carry the risk of potential autoimmune reactions manifesting as dyspnea. Repeated binding and unbinding cycles, impaired platelet turnover, and lung sequestration or apoptosis of overloaded destructive platelets are among the potential mechanism(s) responsible for dyspnea after reversible antiplatelet agents.