Preoperative RRI and Long-term Risk for CKD

Preoperative Renal Resistive Index to Predict Long-term Development of Chronic Kidney Disease in Patients Undergoing Cardiac Surgery

Renal resistive index (RRI) is calculated from ultrasonographic Doppler measurements of flow velocities in intraparenchymal renal arteries. Normal values are around 0.60, and 0.70 is considered the upper normal threshold in adults. Both preoperative and postoperative elevation of RRI has shown promise in early detection of AKI after cardiac surgery. Further, elevated RRI before coronary angiography is associated with an increased risk of cardiovascular complications up to 1 year after the procedure. The role of preoperative RRI in predicting long-term renal and cardiovascular complications after elective surgery is however not known. The aim of this study is to assess the role of preoperative RRI to predict the risk of persistent renal dysfunction as well as renal- and cardiovascular complications up to 5 years after surgery.

Inclusion Criteria:

• Age ≥18
• Elective coronary artery bypass grafting, heart valve surgery, or aortic surgery performed at Karolinska University Hospital between September 2014 and April 2015
• Preoperative measurement of RRI performed with satisfactory Doppler reading
• Written informed consent

Exclusion Criteria:

• Kidney transplant
• Dialysis-dependent kidney disease
• Cancelled surgery
• Missing follow-up data