Association of chronic kidney disease with in-hospital outcomes of transcatheter mitral valve repair

Percutaneous edge-to-edge transcatheter mitral valve repair (TMVr) using MitraClip1 has been approved for the treatment of degenerative mitral valve regurgitation (MR). Chronic kidney disease (CKD) is shown to be an independent predictor for worse outcomes for transcatheter aortic valve replacement. The presence of chronic MR may further deteriorate renal function. However, an association of CKD and/or end-stage renal disease (ESRD) and mortality in patients undergoing TMVr has not been well described. In the EVEREST II trial, the prevalence of CKD was 23%. Most major randomized clinical trials have excluded such CKD patients from the cohorts. Therefore, this study aims to find an association between CKD/ESRD and in-hospital outcomes of TMVr in “real-world” hospitalizations. This study used National Inpatient Sample (NIS) data from the year 2012 to 2014. The NIS database has been described earlier which is sponsored by HealthCare Cost and Utilization Project. Briefly, the NIS includes more than 4000 hospitals across the United States which represents 95% of the US population. This study identifies adult hospitalizations (age 18 years) with TMVr using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) procedure code 35.97 which is specific for mitral valve repair (N = 2570). Hospitalizations with CKD were identified using ICD-9-CM diagnosis codes 585.1–585.5 and 585.9. Hospitalizations with ESRD were identified using ICD9-CM diagnosis code 585.6 or procedures code of hemodialysis (39.95) or peritoneal dialysis (54.98). Calculation of cost was performed by merging cost-to-charge ratio (CCR) with the total cost. These CCR files are provided by the sponsor. The severity of co-morbid conditions was defined using Deyo modification of Charlson co-morbidity Index (CCI). Mann-Whitney U test was used for comparison of continuous variables, while Fischer’s Exact test was utilized for comparison of categorical variables. Finally, multivariate logistic regression analysis was performed to analyze adjusted outcomes and age, gender, race and Elixhauser comorbidities were included in the model. This study was exempted from the intuitional review board committee review. Additionally, all the principles outlined in the Helsinki Declaration of 1975, as revised in 2000, have been followed in all the experiments involving human subjects during the current study. A total of 500 (19.5%) hospitalizations were identified having CKD and 130 (5%) hospitalizations with having ESRD. Baseline differences existed between the groups (Table 1). Mean age was higher in the CKD group (79.1 vs. 72.2 years, P = <0.001) while lower in the ESRD group (64.7 vs. 72.2 years, P = <0.001) as compared to those without CKD or ESRD.