Prevalence, Predictors and Clinical Outcomes of Percutaneous Coronary Intervention For In-Stent Restenosis versus De Novo Coronary Artery Disease.

In-stent restenosis (ISR) remains a challenging complication following percutaneous coronary intervention (PCI), owing to its complex pathogenesis and multifaceted risk factor profile. We performed a retrospective analysis of all PCI data recorded in the Victorian Cardiac Outcomes Registry (VCOR), from 2013 to 2022, dividing patients into the ISR or de novo-PCI groups based on the intervened lesion. The primary outcome was in hospital mortality, with secondary outcomes including 30-day major adverse cardiovascular events and long-term mortality. Among 104,722 total PCI procedures, 4,935 procedures (4.7%) were for ISR, and 99,787 procedures (95.3%) were for de novo coronary lesions. Patients with ISR were older (mean age 69.0 ± 10.7 years vs. 66.4 ± 11.9 years, p < 0.001) with a higher burden of comorbidities including advanced chronic kidney disease (eGFR less than 31ml/min/1.73m2 (4.2% vs. 2.5%, p < 0.001)), peripheral vascular disease (6.3% vs. 3.3%, p < 0.001) and diabetes mellitus (34.8% vs. 22.3%, p < 0.001). Lesion complexity was higher in the ISR group, with more lesions classified as ACC/AHA Type B2 and above (74.8% vs. 59.6%, p < 0.001). Adjunctive imaging devices were more commonly utilized in the ISR group; however, use was generally low (8.4% vs. 2.8%, p < 0.001). In-hospital mortality was lower in the ISR group, whereas 30-day target vessel and lesion revascularization rates were higher (1.3% vs. 0.7%, p < 0.001 and 0.8% vs. 0.4%, p = 0.001 respectively). Long term mortality as assessed over 10 years was higher in the ISR group. In conclusion, compared with de novo PCI, patients undergoing ISR PCI were older with greater comorbidities and lesion complexity. ISR PCI was associated with lower in-hospital mortality but worse long-term survival. These findings provide contemporary, population-based evidence on the evolving clinical profile and outcomes of ISR in routine PCI practice.