Understanding long-term risk in Percutaneous Coronary Intervention (PCI) in the Australian contemporary era with a focus on defining Complex Revascularisation in High-Risk Indicated Patients (CHIP).

Background: Complex Revascularisation in High-Risk Indicated Patients (CHIP) is emerging in Percutaneous Coronary Intervention (PCI). We document the frequency and outcomes following CHIP PCI in the Australian population, to understand risk and guide clinical decision-making. We propose a scoring system to define CHIP procedures.

Methods: Patients undergoing PCI from Melbourne Intervention Group registry between 2005 and 2018 were analysed. Patients were stratified based on the number of high-risk features defined as 1)presence of ≥3 patient factors including age > 75yo, COPD, diabetes, renal impairment (eGFR<60 mL/min/1.73 m2), PVD, and 2)LVEF<30 %, and/or 3)having one complex coronary anatomical feature such as LMCA PCI, ACC/AHA B2/C lesion PCI, presence of multi-vessel disease or CTO PCI. National Death Index linkage was performed for long-term mortality analysis. Outcomes were analysed according to 4 risk categories - low risk(score 0), intermediate risk(score 1), high-risk(score 2), and very high-risk(score 3).

Results: 20,973patients were analysed. Majority of patients underwent intermediate-risk procedures(71.7 %), with low rates of high-risk(6.6 %), and very high-risk(0.2 %). Lesion success inversely correlates with risk; low-risk(99.4 %), intermediate-risk(95.1 %), high-risk(94.3 %), very high-risk(92.5 %),p < 0.001. In-hospital and 30-day death correlates with risk; low-risk(0.0 %/0.1 %), intermediate-risk(0.3 %/0.5 %), high-risk(1.5 %/2.9 %), very high-risk(2.4 %/7.1 %),p < 0.001. Long-term mortality correlates with risk; low-risk(12.3 %), intermediate-risk(15.8 %), high-risk(49.3 %), very high-risk(76.2 %),p < 0.001. On multivariate analysis, increasing risk correlates with long-term mortality; intermediate-risk(HR1.41), high-risk(HR6.42), and very high-risk(14.05).

Conclusion: In the Australian practice, proportion of patients undergoing high and very high-risk PCI procedures are low. Despite good procedural success and in-hospital outcomes, long-term mortality is poor. Further research into appropriate patient selection, and direct comparison of CHIP PCI to those treated medically and surgically should be considered.