Is CT to blame for the decline in renal function after EVAR?

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Renal function after EVAR deteriorates over one year when follow-up protocol includes contrast enhanced computerised tomography (CT), a new study presented at the iCON conference, in Phoenix, USA, has shown.

Jan Brunkwall, University of Cologne, Germany, told delegates that open repair patients have stable renal function over one year, and that contrast might be the cause of renal function deterioration in EVAR patients. The aim of study, he said, was to compare renal function during one-year follow-up in open repair patients, who did not have CT scan during follow-up, and in EVAR patients who had CT scans. Patients were followed at one, three, six and 12 months postoperatively.

 

Creatinine clearance tests with the Crockcroft-Gault formula showed statistically significant difference between EVAR and open repair patients at discharge and at 12 months. At discharge creatinine level was 67.3+/-28ml/min in EVAR patients and 78.5+/-33ml/min for open repair (p

 

Brunkwall said that tests using the Modification of Diet in Renal Disease (MDRD) formula also showed statistically significant difference at 12 months. Creatinine levels were 63+/-18ml/min for EVAR patients and 76.4+/-28ml/min for open repair patients (p

 

In relation to age, Brunkwall presented data showing that patients over 70 years are more at risk of renal function deterioration. In the EVAR group, creatinine levels were 79.9+/-24ml/min for patients under 70 years and 54+/-17ml/min for patients over 70 years. Similar differences were also seen in the open repair group.

 

Brunkwall told delegates that ultrasound with contrast enhancement is one of the methods that may replace CT. He showed data from the paper ‘Contrast-enhanced ultrasound versus computed tomographic angiography for surveillance of endovascular abdominal aortic aneurysm repair’, by Ten Bosch et al (J Vasc Interv Radiol. 2010 May; 21(5):683-43). The results of this study showed that contrast-enhanced ultrasound demonstrated more endoleaks, predominantly of type II, compared with CT angiography (53% vs. 22% of the cases). “Ultrasound was as accurate as CT angiography in the assessment of maximal aneurysm sac diameters. The interobserver variability for aneurysm size measurement by ultrasound was low, given the interclass correlation coefficients of 0.99 and 0.98,” he said.

 

In conclusion, Brunkwall said that fewer CT scans should be performed in order to preserve renal function. “Ultrasound with contrast enhancement and plain abdominal X-ray may replace CT.”

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