Coronary artery disease
A Comparison of Contemporary Definitions of Contrast Nephropathy in Patients Undergoing Percutaneous Coronary Intervention and a Proposal for a Novel Nephropathy Grading System

https://doi.org/10.1016/j.amjcard.2007.10.051Get rights and content

Contrast-induced nephropathy (CIN) after percutaneous coronary intervention (PCI) has multiple definitions. We attempted to identify the optimal definition of CIN. In 985 patients undergoing PCI (derivation group), we assessed the prognostic significance of 4 commonly used contemporary definitions of CIN (increases in serum creatinine after PCI [δCr] >1.0 mg/dl, >0.5 mg/dl, and >25% after PCI; and the American College of Cardiology National Cardiovascular Data Registry definition) with respect to 6-month major adverse cardiovascular events (MACEs) and all-cause mortality (at 863 ± 324 days). Incidence of CIN ranged widely (2.0% to 15%) depending on the definition used. Only 2 definitions (δCr >0.5 mg/dl, >25%) consistently correlated with study outcomes. Using these 2 definitions, we devised a new grading system (grade 0 δCr ≤25% and ≤0.5 mg/dl; grade 1 δCr >25% but ≤0.5 mg/dl; and grade 2 δCr >0.5 mg/dl). Nephropathy grades (0 vs 1 vs 2) showed significant correlation with 6-month MACEs (12.4 vs 19.4 vs 28.6%, p = 0.003) and all-cause mortality (10.2 vs 10.4 vs 40.9%, p <0.0001). In multivariate analyses, the grading system showed an independent association with MACEs and mortality. The prognostic value of nephropathy grades was prospectively confirmed in an independent validation group of 539 patients. In conclusion, of the 4 contemporary definitions of CIN, only δCr >25% and >0.5 mg/dl consistently predicted adverse events after PCI. By unifying these 2 definitions, we devised a novel nephropathy grading system that is predictive of 6-month MACEs and all-cause mortality after PCI.

Section snippets

Methods

We prospectively collected baseline clinical, angiographic, and in-hospital outcome (death, infarction after PCI or reinfarction, and target vessel revascularization) data in all patients undergoing PCI at the Guthrie Clinic/Robert Packer Hospital. Measurement of serum creatinine before PCI and the day after PCI is strongly encouraged. Subsequent measurements of serum creatinine during hospital stay are recommended, especially if an increase in serum creatinine is noted on the day after PCI or

Results

Clinical characteristics are listed in Table 1. Baseline renal insufficiency was seen in 25% and positive biomarkers in 48%. Incidence of CIN by each of the 4 definitions, in all patients, selected high-risk subgroups, and low-risk subgroup, is presented in Table 2. The incidence of CIN varied widely, from 2.0% (using the ACC-NCDR definition) to 15.0% (using the δCr >25% definition) in the study population. High-risk subsets, such as age >65 years, diabetes mellitus, abnormal cardiac biomarkers

Discussion

In patients undergoing PCI, the incidence of CIN varies widely depending on the definition used. Of the 4 contemporary definitions, only 2 (δCr >0.5 mg/dl and >25%) consistently predicted clinical outcomes. Compared with δCr >25%, the δCr >0.5 mg/dl definition provides greater discrimination between unselected patients and patients at high risk for CIN and is a more robust indicator of poor outcomes. Based on these findings, we propose a novel nephropathy grading system that unifies the δCr

Acknowledgment

We acknowledge the assistance of Sue Tomaszycki with the figures.

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