Anemia Among Patients Undergoing Transcatheter Mitral Valve Repair: From the National Inpatient Sample in the United States

Background The prevalence and impact of anemia on the outcomes of transcatheter mitral valve repair (TMVr) have not been well-studied. Anemia is a commonly encountered comorbidity among patients with cardiovascular disorders and is frequently under-recognized. The study aimed to analyze the prevalence of anemia and its impact on post-TMVr in-hospital outcomes. Methods The National Inpatient Sample (NIS) was queried to identify all patients who underwent TMVr from 2011-2015 in the United States by utilizing suitable International Classification of Diseases, Ninth Revision (ICD-9) codes. The baseline characteristics and in-hospital outcomes were compared among patients with and without anemia. Results A total of 4,382 patients were identified. Out of these, 978 (22.3%) patients had baseline anemia. Anemic patients were noted to have a higher burden of co-morbidities, including chronic kidney disease, hypertension, and diabetes mellitus. The in-hospital mortality was higher but not statistically significant between anemic and non-anemic patients (3.6% vs 2.6%; odds ratio (OR): 1.44; confidence interval (CI): 0.85-2.46, p=0.179). The other adverse outcomes, including the length of stay, the requirement for blood transfusions, the incidence of post-implant acute kidney injury, hemodialysis, and the cost of hospitalization, were higher in anemic patients. Conclusion Anemia was present in one out of five patients undergoing TMVr in this nationally representative cohort. Baseline anemia showed numerically higher but not statistically significant in-hospital mortality and was associated with other in-hospital adverse outcomes. Further larger studies are needed to highlight the importance of anemia in the TMVr procedure.