BACKGROUND: Positive psychological factors such as optimism are predictive of favorable clinical outcomes in patients with cardiac disease. Evidence suggests that trait optimism can vary over time, especially after a coronary event. We therefore examined whether the level and change in optimism across the one-year time period after percutaneous coronary intervention (PCI) were associated with changes in quality of life (QoL) over time. The analyses were adjusted for negative psychological functioning and health behavior adherence as potential explanatory factors. METHODS: Patients who underwent PCI (n = 1759, 21 % female, mean age = 64 ± 10 years) filled out a psychological survey including positive (optimism
LOT-R) and negative psychological factors (depression (PHQ9) and anxiety (GAD7)), QoL (WHOQOL-BREF), and health behavior adherence (MOS-GAS) at inclusion and one year later (n = 1474). Data were analyzed using hierarchical linear mixed modeling with time-varying predictors and covariates. RESULTS: Optimism levels increased from baseline (Mean CONCLUSION: These data indicate marked individual differences in the magnitude of changes in optimism following PCI. Both higher levels and increases in optimism were associated with higher and improving QoL. Depression and anxiety, but not health behavior adherence, explained part of this relationship. Optimism might be an important psychological factor to address in cardiac rehabilitation.