Factors Contributing to the Lower Mortality with Ticagrelor Compared with Clopidogrel in Patients Undergoing Coronary Artery Bypass Surgery

Objectives: This study investigated the differences in specific causes of post-coronary artery bypass graft surgery (CABG) deaths in the PLATO (Platelet Inhibition and Patient Outcomes) trial.

Background: In the PLATO trial, patients assigned to ticagrelor compared with clopidogrel and who underwent CABG had significantly lower total and cardiovascular mortality.

Methods: In the 1,261 patients with CABG performed within 7 days after stopping study drug, reviewers blinded to treatment assignment classified causes of death into subcategories of vascular and nonvascular, and specifically identified bleeding or infection events that either caused or subsequently contributed to death.

Results: Numerically more vascular deaths occurred in the clopidogrel versus the ticagrelor group related to myocardial infarction (14 vs. 10), heart failure (9 vs. 6), arrhythmia or sudden death (9 vs. 3), and bleeding, including hemorrhagic stroke (7 vs. 2). Clopidogrel was also associated with an excess of nonvascular deaths related to infection (8 vs. 2). Among factors directly causing or contributing to death, bleeding and infections were more common in the clopidogrel group compared with the ticagrelor group (infections: 16 vs. 6, p < 0.05, and bleeding: 27 vs. 9, p < 0.01, for clopidogrel and ticagrelor, respectively).

Conclusions: The mortality reduction with ticagrelor versus clopidogrel following CABG in the PLATO trial was associated with fewer deaths from cardiovascular, bleeding, and infection complications. (Platelet Inhibition and Patient Outcomes [PLATO]; NCT00391872).