Can the Predictive Value for Contrast Nephropathy Be Improved by Using Ejection Fraction Instead of New York Heart Association Class When Calculating the Mehran Risk Score?

Abstract

Introduction: Congestive cardiac failure (CCF) is a known risk factor for contrast-induced nephropathy (CIN) complicating coronary angiography +/- intervention. However, the definition of CCF in guidelines and risk scores on CIN, including the Mehran score, varied between undefined to the use of New York Heart Association (NYHA) symptoms or ejection fraction (EF). The aim of this study was to compare the predictive value of NYHA versus ejection fraction for CIN within the Mehran score. Methods: A retrospective review was done on 331 patients with known renal outcomes at least 48 hours post coronary angiography +/- intervention. Patients were stratified into low, medium and high risk groups based on the Mehran score. NYHA symptoms were determined based on documentation of symptoms in patient records. Ejection fractions were determined via Simpson's biplane method on 2D echocardiography. Statistical analysis was done using logistic regression and receiver operating curves. Results: Using NYHA class III/IV symptoms as the marker for CCF, the area under the ROC curve (AUC) pre angiography was 0.62 (95% CI 0.58- 0.69). Post angiography, with contrast volumes included, the AUC improved to 0.64 (95% CI 0.58- 0.69). In comparison, AUC pre angiography using ejection fraction (EF) of <50% was 0.68 (95% CI 0.63-0.73). This increased to 0.70 (95% CI 0.64-0.74) post angiography. The difference in AUC between NYHA class and EF was not statistically significant. Conclusion: Using EF instead of NYHA class numerically improved the predictive value of the Mehran risk score for contrast nephropathy, but the difference was not statistically significant. Larger studies comparing specifically NYHA and ejection fraction are needed to further elucidate the association between these CCF markers and risk of CIN.