Outpatient Management of Gastrointestinal Bleeding in Patients with Continuous-Flow Left Ventricular Assist Devices

Background: Renal dysfunction (RD) is common in heart failure (HF) and is an important predictor of mortality in patients undergoing left ventricular assist device (LVAD) placement. Evaluation of renal function in LVAD candidates is generally accomplished via serum creatinine (Cr) based estimates. This is problematic since Cr level is influenced not only by renal function but also the amount of Cr produced by skeletal muscle. Since cardiac cachexia is common in HF, it is unclear to what degree reduced muscle mass and Cr production will affect estimates of glomerular filtration rate (GFR). Hypothesis: We hypothesized that, in patients referred for LVAD placement, Cr production would be significantly lower than predicted resulting in a significant underestimation of the burden of RD in these patients. Methods: Consecutive adult patients who underwent LVAD placement with 24-hour Cr collections available were studied (n562). Cr production was determined using the 24 hour cumulative Cr excretion; measured Cr clearance was calculated using the standard clearance equation. Renal function was also estimated from the serum Cr using the Cockgroft-Gault (CG) equation and the CKD-EPI equation. All parameters of renal function were indexed to a BSA of 1.73 m. Results: The mean age of the cohort was 54.5 6 14.6 years, 74.3% (n546) were male and 51.6% (n532) were African American. Despite an elevated BMI of 29.9 6 8.06 kg/m, the mean 24 hour Cr excretion was only 12796 474 mg (compared to a predicted value in this cohort of 19386 615 mg, p!0.001) confirming marked sarcopenia. Overall, less than 30% of patients’ Cr excretion was in the normal range after accounting for age and BSA. Significant preLVAD RD was present with a mean measured Cr clearance of 49.5 6 22.3 ml/min/ 1.732. Both the CG and the CKD-EPI equation overestimated GFR with a median error of 22.3% (10.9-34.0%) and 19.8 % (10.4-31.2%) respectively. This translated into 25.8% of the patients being misclassified using CKD-EPI and 35.5% being misclassified by CG into a greater CKD stage than indicated by measured Cr clearance. Conclusions: HF patients undergoing LVAD placement exhibit decreased Cr production likely as a result of significant cardiac cachexia. Since GFR estimation equations assume normal Cr production, this led to significant overestimation of GFR and misclassification of patients into higher CKD stages. Further research is necessary to determine if non-creatinine based metrics of renal function could improve preLVAD evaluation of RD.