Clinical impact of dyspnoea after ticagrelor treatment and the effect of switching to clopidogrel in patients with myocardial infarction

Background: Dyspnoea is frequent during ticagrelor-based dual antiplatelet therapy (DAPT) for acute myocardial infarction (AMI). However, its clinical characteristics or management strategy remains uncertain. Methods: The study assessed 2,617 AMI patients from the Ticagrelor versus Clopidogrel in Stabilized Patients with AMI (TALOS-AMI) trial. Dyspnoea during 1-month ticagrelor-based DAPT and following DAPT strategies with continued ticagrelor or de-escalation to clopidogrel from 1 to 12 months were evaluated for drug adherence, subsequent dyspnoea, major adverse cardiovascular events (MACE), and bleeding events. Results: Dyspnoea was reported by 538 patients (20.6%) during 1 month of ticagrelor-based DAPT. Adherence to allocated DAPT over the study period was lower in the continued ticagrelor arm than the de-escalation to clopidogrel, particularly among the dyspnoeic population (81.1% vs. 91.5%, p<0.001). Among ticagrelor-treated patients with dyspnoea, those switched to clopidogrel at 1 month had a lower frequency of dyspnoea at 3 months (34.3 vs. 51.7%, p<0.001) and 6 months (25.5% vs. 38.4%, p=0.002) than those continued with ticagrelor. In patients with dyspnoea in their 1-month ticagrelor-based DAPT, de-escalation was not associated with increased MACE (1.3% vs. 3.9%, hazard ratio [HR] 0.31, 95% confidence interval [CI] =0.08-1.11, p=0.07) or clinically relevant bleeding (3.2% vs. 6.2%, HR 0.51, 95% CI 0.22-1.19, p=0.12) at 1 year. Conclusions: Dyspnoea is a common side effect among ticagrelor-based DAPT in AMI patients. Switching from ticagrelor to clopidogrel after 1 month in AMI patients may provide a reasonable option to alleviate subsequent dyspnoea in ticagrelor-relevant dyspnoeic patients, without increasing the risk of ischaemic events (NCT02018055).