In 2 phase II studies, dyspnea was noted to occur as a side effect to ticagrelor in a dose-dependent fashion; and in the PLATO study, there was a 6% absolute excess of dyspnea in ticagrelor-treated patients compared with patients treated with clopidogrel. In the ONSET/OFFSET study dyspnea was more commonly associated with ticagrelor therapy in comparison with clopidogrel and placebo in patients with stable coronary artery disease (38.6%, 9.3%, and 8.3%, respectively), but was not associated in this study with any adverse change in cardiac or pulmonary function. This result was confirmed in patients with acute coronary syndrome.