Background <p>The type of atrial fibrillation (AF) is assumed as a vital factor in AF patients’ prognosis. However, its impact on clinical outcomes remains unclear in patients with AF complicated with acute coronary syndrome (ACS) or undergoing percutaneous coronary intervention (PCI).</p> Methods <p>This study was a prospective, observational, single center study of adults with AF and ACS/PCI. The primary endpoint was major adverse cardiovascular events (MACE), and secondary endpoint was net adverse clinical outcome events (NACE), a composite of MACE events and major bleeding events.</p> Results <p>A total of 1,762 participants were enrolled in this study, 1,137 of them were paroxysmal AF and 625 were non- paroxysmal AF, with a median follow up time of 1,023&#xa0;days. The mean age of this population was 67 ± 10 and 27.2% were female. Kaplan–Meier curves showed patients were under a higher incidence of both MACE (<i>p</i> &lt; 0.001) and NACE (<i>p</i> &lt; 0.001) in patients with non-paroxysmal AF. Multivariate Cox analysis showed that patients with non-paroxysmal AF had a higher risk of MACE (HR: 1.322; 95%CI 1.074–1.626) and NACE (HR: 1.341; 95%CI 1.095–1.644) compared to those with paroxysmal AF.</p> Conclusions <p>Our study demonstrated that among patients with ACS/PCI, those with non-paroxysmal AF were more likely to experience MACE and NACE.</p>