Ticagrelor versus Clopidogrel in Acute Coronary Syndromes

To the Editor: In the Study of Platelet Inhibition and Patient Outcomes (PLATO), Wallentin et al. (Sept. 10 issue) 1 found that in patients with acute coronary syndromes, the use of ticagrelor, as compared with clopidogrel, significantly reduced the rate of death, myocardial infarction, or stroke without increasing the rate of bleeding. Ticagrelor, a direct-acting oral antagonist of the adenosine diphosphate receptor, was associated with adverse events, including dyspnea, ventricular pauses, and increased levels of creatinine and uric acid. Although the mechanism of these effects is unknown, components of the molecular structure of ticagrelor are almost identical to those of adenosine, which can be degraded to uric acid, and it is conceivable that metabolites of ticagrelor activate adenosine receptors. It is well known that adenosine induces dyspnea by broncho