AbstractBackgroundLimited data are available on the risk of periprocedural myocardial infarction (MI) in patients undergoing complex versus noncomplex percutaneous coronary intervention (PCI).MethodsWe assessed the risk of periprocedural MI according to the fourth Universal definition of myocardial infarction (UDMI) and several other criteria among patients undergoing elective PCI in a prospective, single‐center registry. Complex PCI included at least one of the following: 3 coronary vessels treated, ≥3 stents implanted, ≥3 lesions treated, bifurcation with 2 stents implanted, total stent length >60 mm, treatment of chronic total occlusion, and use of rotational atherectomy.ResultsBetween 2017 and 2021, we included 1010 patients with chronic coronary syndrome, of whom 226 underwent complex PCI (22.4%). The rate of periprocedural MI according to the fourth UDMI was significantly higher in complex compared to noncomplex PCI patients (26.5% vs. 14.5%, p < 0.001). Additionally, periprocedural MI was higher in the complex PCI group using SCAI (4% vs. 1.1%, p = 0.009), ARC‐2 (13.7% vs. 8.0%, p = 0.013), ISCHEMIA (5.8% vs. 1.7%, p = 0.002), and EXCEL criteria (4.9% vs. 2.0%, p = 0.032). SYNTAX periprocedural MI occurred at low rates in both groups (0.9% vs. 0.6%, p = 0.657). Complex PCI was an independent predictor of the fourth UDMI periprocedural MI (odds ratio [OR] 1.54, 95% confidence interval [CI]: 1.04–2.27, p = 0.031).ConclusionsIn patients with chronic coronary syndrome undergoing elective PCI, complex PCI is associated with a significantly higher risk of periprocedural MI using multiple definitions. These findings highlight the importance of considering upfront this risk in the planning of complex PCI procedures.