Correlation of Ablation Volume with Renal Function Loss after Cryoablation in Solitary Functioning Kidneys

To determine the degree of renal function deterioration after renal cryoablation in patients with a solitary functioning kidney on the basis of ablation volume.

Over a 15-year period, 81 percutaneous cryoablations were performed in solitary functioning kidneys. After exclusion of patients with baseline end-stage renal disease (ESRD) and insufficient follow-up, analysis was performed on 65 procedures in 52 patients (40 men; mean age, 63.5 years). The postcryoablation renal function was based on the lowest serum creatinine within 6 months after procedure. Renal function change was defined as percentage glomerular filtration rate (GFR) change. Volumetric analysis was performed on the target lesion, renal parenchyma, and ablation zone.

The median tumor diameter was 2.0 cm (range, 0.8-4.7 cm). The median baseline GFR decreased from 56.4 mL/min/1.73 m² (range, 17.5-89.7 mL/min/1.73 m²) to 46.9 mL/min/1.73 m² (range, 16.5-89.7 mL/min/1.73 m²) at median of 95 days (P < .001), equating to a -7.9% median renal function change (range, -45.0% to +30.7%). All patients had Stage 2 or worse chronic kidney disease, and baseline function did not correlate with renal function change. The median volume of ablated parenchyma was 19.7 mL (range, 2.4-87.3 mL), equating to 8.1% (range, 0.7%-37.2%) of total parenchyma. The volume of parenchymal volume ablated correlated significantly with renal function loss, whereas age, hypertension, and diabetes mellitus did not. No patient developed ESRD within 1 year after cryoablation.

Cryoablation in solitary functioning kidneys resulted in a modest reduction in renal function, even in patients with chronic kidney disease and ablations of up to 20% of renal parenchymal volume.