SAN FRANCISCO—The ratio of contrast volume use to estimated glomerular filtration rate (CVeGFRr) can reliably predict the development of contrast-induced nephropathy (CIN) after a percutaneous coronary intervention (PCI), according to data from an observational study reported at the American College of Cardiology annual meeting.

“Our results suggest that contrast volume:eGFR ratio might be applied prospectively to calculate the maximum amount of contrast to give without increasing the risk of CIN after PCI,” said Venkatesan Dyanesh Vidi, MD,  a cardiology fellow at Long Island Jewish Medical Center in New Hyde Park, N.Y.

Dr. Vidi and colleagues examined the usefulness of CVeGFRr for predicting CIN in 3,549 patients who had undergone PCI procedures during a recent 21-month period. CIN develops in about 10% of patients following a PCI procedure, Dr. Vidi said. The onset of CIN increases the in-hospital morbidity by roughly 10%-20%.

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The likelihood of CIN is driven by baseline risk factors such as patient age, diabetes, anemia, and heart failure, for example, he added. Conditions that increase the risk of CIN, however, are not typically modifiable at the time of PCI, and thus other strategies to reduce the risk of CIN are necessary.

Currently, hydration with normal saline is recommended by various guidelines for the prevention of CIN, however about 10% of patients will still develop CIN after PCI.

In the present study, CIN occurred in 279 patients, or 7.65%, after PCI. Multivariate analysis showed that female gender, history of diabetes, left ventricular ejection fraction less than 45%, cardiogenic shock in the prior 24 hours, CVeGFRr greater than 3, and salvage PCI were independent predictors of CIN after PCI.

CIN was 1.8 times as likely to develop in patients with a CVeGFRr  of 3 or higher than in patients with a CVeGFR less than 3.

“Essentially we have developed a simple tool which is independent of other baseline risk factors for identifying risk of CIN,” Dr. Vidi said. “And “3” is the important number to remember. So, for example, if the patient’s GFR is 50, I cannot give the patient more than 150 cc’s of contrast, or three times his/her GFR, or else I increase the risk of CIN significantly.”

Dr. Vidi emphasized that a lack of information in the database on the type of contrast used during PCI (low-osmolar versus iso-osmolar) may represent a limitation of his research.

In addition, the study was retrospective, conducted at two high-volume centers, and included patients with the entire spectrum of coronary artery disease presentation, which might have decreased the effect size of CVeGFR in the multivariable model.

Finally, while multivariate adjustment was performed, the analysis does not categorically exclude the possibility of unmeasured confounding.

The present study included “all comers with acute coronary syndrome,” he said, adding that future studies should focus on patients with ST-elevation myocardial infarction who have a markedly higher risk of CIN than other stable patients.