Coronary artery aneurysm (CAA) formation is a rare complication after percutaneous coronary intervention (PCI)with stent implantation. Why CAA occurs in these unusual instances is not well understood. Though cases with drug-eluting stent (DES) induced CAA have been reported before, none was reported to be associated with a titanium nitric oxide-coated bioactive stent. Herein, we describe the first case where CAAdeveloped after titanium nitric oxide-coated bioactive stent implantation. Several mechanismsmay account for stent-related CAAformation,including mechanical trauma, vessel remodeling, acute myocardial infarction, long or multiple DES stent implantation, DES malapposition and hypersensitivity reaction to polymers.A 53-year-old man presented initially with recent MI and ongoing chest pains. Coronary angiography revealed a 90% occlusion of the middle left anterior descending coronary artery (LAD). PCI was performed on the patient, and a titanium nitric oxide-coated bioactive stent was implanted. Due to a positive thallium scan 28 months later, a follow-up coronary angiography scan revealed a true CAA, which was then further confirmed by intravascular ultrasound. Thereafter, the patient remained asymptomatic at subsequent follow-ups, and continued medical treatment without further intervention. Herein, we discuss the possible etiologies, mechanisms and further treatments of CAA formation after titanium nitric oxide-coated bioactive stent implantation.