Associations of Postoperative Hemoglobin Level and Clinical Outcomes in Patients Undergoing Mitral Valve Surgery.

Abstract

Postoperative hemoglobin could indicate useful information for transfusion practices. The aim of this study was to investigate the association of optimal hemoglobin level and clinical outcomes after mitral valve surgery (MVS). This investigation was a multicenter observational cohort study including 1,518 patients undergoing mitral valve surgery from 2016 through 2018. Patients were separated into six predefined groups based on initial postoperative hemoglobin (< 7.5 g/dL, 7.5 - 8.4 g/dL, 8.5 - 9.4 g/dL, 9.5 - 10.4 g/dL, 10.5 - 11.4 g/dL, ≥ 11.5 g/dL). Multivariable regression analysis was used to adjust laboratory results and surgical features of patients to evaluate the relationships between initial hemoglobin after MVS and clinical outcomes. Patients with initial postoperative hemoglobin below 7.5 g/dL had longer length of stays [mean (95% confidence interval [CI]), 1.9 (1.093 - 1.367)] in comparison with the reference group of 9.5 - 10.4 g/dL. Similarly, for those with hemoglobin below 7.5 g/dL, the odds (95% CI) for secondary outcomes included myocardial infraction 11.801 (1.353 - 22.966) and thrombosis 5.113 (1.340 - 9.508). However, for clinical outcomes, there was no significant difference between the five groups with hemoglobin greater than 7.5 g/dL. In patients after MVS, initial postoperative hemoglobin values below 7.5 g/dL was associated with worse outcomes compared to other values. Given similar outcomes between hemoglobin more than 7.5 g/dL groups, targeting treatment to an initial postoperative hemoglobin value at the lower value may be more desirable.