Association of Intrarenal Resistance Index and Systemic Atherosclerosis After Kidney Transplantation.

Abstract

Background Patients after kidney transplant are at risk of cardiovascular morbidity. Surveillance of kidney transplants is mandatory to ensure a maximal transplant lifespan. Renal function is measured by levels of creatinine (clearance) while morphological aspects and other parameters like the kidney-size and Resistance Index are assessed with Duplex sonography. An elevated Resistance Index is associated with renal graft failure. The Resistance Index can also be measured in the carotid artery. It is uncertain whether a correlation between intrarenal RI after kidney transplant and the RI of the internal carotid artery exists. Material and Methods Resistance index of kidney transplants and of the carotid artery were measured with duplex sonography in adult patients after kidney transplant. Carotid intima-media thickness as well as the Framingham risk score and the Augmentation index, all known markers of atherosclerosis, were assessed. Statistical analysis was performed with STATA. Continuous data were expressed as means +/- standard deviation and compared by Kruskal-Wallis Test. Correlations between the RI in Carotid artery and the RI of the kidney transplant were based on Spearmen test with the level of significance set at p < 0.05. Results 98 consecutive patients (60% male, mean age of 48.7 (+/-15.6)) were included. Mean interval after transplantation was 27.5 (+/- 8.5) months and the mean serum creatinine was 308 (+/- 220.3) mmol/L. The RI of the internal carotid artery and the renal transplant were significantly correlated (p < 0.05). A strong correlation between the RIs and the Augmentation Index (AIx) was found. Conclusion The RI of the kidney transplant is correlated with the RI of the carotid artery and to markers of general atherosclerosis. This observation may be helpful to identify patients after kidney transplant with higher risk for cardiovascular events.