Seven key patient factors and six procedural factors are associated with higher risk and more complex percutaneous coronary intervention (PCI) procedures and could inform a long-sought “CHIP” score, according to a new 10-year analysis of the British Cardiovascular Intervention Society (BCIS) database encompassing more than 300,000 patients.
The patient factors are: older age (≥80 years), being female, having previous stroke or previous myocardial infarction (MI), peripheral vascular disease, ejection fraction (EF) <30% and chronic renal disease.
Procedural factors include: rotational atherectomy, left main PCI, three-vessel PCI, dual arterial access, planned left ventricular (LV) mechanical support, and total lesion length >60 mm.
The findings could be used to develop a complex high-risk indicated percutaneous coronary intervention (CHIP-PCI) score for risk modification – a concept for which they said there has been “much enthusiasm” in recent years, but little progress with few studies and a lack of robust criteria.
The results were published Monday online, ahead of the Jan 10. issue of JACC: Cardiovascular Interventions, by Majd Protty, MD, from the University Hospital of Wales, and fellow authors.
A total of 313,054 patients from the BCIS database were included, all of whom underwent PCI procedures in the U.K. between January 2006 and December 2016.
The data included over 120 variables detailing patient demographics, clinical and procedural characteristics and in-hospital outcomes. Records with incomplete data on major adverse cardiac or cerebrovascular events (MACCE) or unknown ejection fraction were excluded from the current analysis.
A multiple logistic regression model was developed to identify variables associated with in-hospital MACCE and to construct the CHIP score. An integer score was assigned to each CHIP factor based on its effect size on the observed odds ratio (OR) for MACCE compared with baseline as follows: >2.0 = 3 points, 1.5-2.0 = 2 points, 1.0-1.5 = 1 point.
Based on the observed OR, planned LV mechanical support scored 3 points, age ≥80 years, peripheral vascular disease, EF <30% and chronic renal disease all scored 2 points; and remaining factors each scored 1 point.
Overall, in-hospital MACCE was 0.6% when no CHIP factors were present compared with 1.2% with any associated CHIP factor (P < 0.001).
“As the CHIP score increased, there was an exponential increase in observed in-hospital MACCE,” the researchers added, with steeper increases observed between scores of 3 and 5 (CHIP 3 and CHIP 5).
“The observed MACCE for CHIP 5 was 3.2% and as such, based on a >5 x increase in the observed MACCE compared with a CHIP score of 0, a CHIP score threshold of 5 was arbitrarily defined as a CHIP case,” they added.
“The identification of CHIP factors and scores may facilitate personalized assessment and management of complex and high-risk patients undergoing PCI,” the researchers concluded. They stressed that, despite the existence of well-established risk scores – such as EuroSCORE and EuroSCORE II – for surgical revascularization, “risk prediction in PCI is less well established.”
Nevertheless, in an accompanying editorial, Ochsner Louisiana State University Health’s Tarek Helmy, MD, and George Mina, MD, stressed the “inherent limitations” of the current study, including that the cutoff point is self-admittedly “arbitrary,” that it has not been externally validated, and that it is limited to the variables collected in the database, “which do not include outcomes beyond hospital discharge.”
Still, the editorialists stressed the importance of establishing a reliable evidence-based definition of CHIP that is reproducible and widely applicable to guide decision-making for high-risk cases, adding: “Protty et al took serious steps towards achieving these goals, and future studies should build on their effort.”
Protty M, Sharp ASP, Gallagher S, et al. Defining Percutaneous Coronary Intervention Complexity and Risk: An Analysis of the United Kingdom BCIS Database 2006-2016. JACC: Cardiovasc Interv 2022;15:39-49.
Helmy T, Mina G. CHIP Score: Do We Really Need One? JACC: Cardiovasc Interv 2022;15:50-51.
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