AIMS
Patients undergoing complex percutaneous coronary intervention (PCI) have a poorer prognosis compared with those treated with non-complex PCI, underscoring the importance for optimal secondary prevention. By incorporating PCI complexity into our PCI registry, we aimed to identify high-risk patients and evaluate contemporary clinical practice, specifically dual antiplatelet therapy and cholesterol management, and outcomes.

METHODS AND RESULTS
The South-East Netherlands Heart Registry (ZON-HR) is an ongoing, multicentre PCI registry collecting patient characteristics, procedural data, laboratory values, medication use, and clinical outcomes. A protocol was implemented recommending prolonged dual antiplatelet therapy for patients with chronic coronary syndrome undergoing complex PCI, with treatment decisions left to the discretion of the treating physician. For the present analysis, all patients with completed 1-year follow-up were included, except those undergoing a PCI comprising two or more complex PCI features.
In our registry, complex PCI is defined as PCI of chronic total occlusion (CTO) (n=368), two-stent PCI of bifurcation lesion (n=233), PCI of the venous graft (n=165), or total stent length of ≥ 60 mm (n=1081). Baseline characteristics were compared between patients undergoing complex PCI (n=1847) and non-complex PCI (n=6796). Cox proportional hazards regression analyses were performed to evaluate the impact of complex PCI and different complex PCI subtypes on 1-year major adverse cardiovascular and cerebrovascular events, as well as on the individual components.
Patients undergoing a complex PCI are older (69.4 vs 67.6 years, p<0.01), more often male (77.6% vs 71.7%, p<0.01) and have more risk factors compared to patients undergoing a non-complex PCI. The most pronounced baseline differences were observed in patients undergoing PCI of the venous graft.
Overall, complex PCI group was associated with a 1.63-fold increased risk of major adverse cardiovascular and cerebrovascular events compared with non-complex PCI (p<0.01), primarily driven by myocardial infarction and unplanned revascularization. After multivariable adjustment, the risk of myocardial infarction remained significantly higher in the complex PCI group (adjusted HR 1.52, 95% CI 1.03-2.24).
After first comparing outcomes between complex and non-complex PCI, subsequent analyses stratified complex PCI into its individual subtypes and compared each subtype with non-complex PCI. Within the complex PCI group, PCI involving bifurcation stenting emerged as a significant independent predictor of myocardial infarction (HR 2.75, 95% CI 1.33-5.68). No significant differences for PCI of the venous graft, total stent length of ≥ 60 mm and PCI of CTO were observed after adjustments for covariates.

CONCLUSIONS
In this real-world PCI registry, patients undergoing complex PCI, particularly bifurcation lesions, remained at increased risk of ischemic events. These findings suggest that more rigorous secondary prevention is needed to fully mitigate ischemic risk in complex PCI and highlight the need for improved risk stratification and even more tailored treatment strategies.