The Effects of Hyponatremia on Ventricular Assist Device Implant Outcomes: A Single Center Study

Background: Hyponatremia is a common electrolyte disorder in patients with advanced heart failure. Preoperative hyponatremia has been identified as an independent risk factor for increased mortality, longer hospitalizations, and postoperative complications following cardiac surgery (1). However, few studies have examined the impact of hyponatremia on postoperative Right Ventricular (RV) function after Left Ventricular Assist Device (LVAD) implantation. This study aimed to determine the association between pre- and post-operative serum sodium levels and surgical outcomes following Abbott Heartmate 3 TMinsertion. Methods: Perioperative serum sodium levels were assessed at pre-operative, early post-operative (1-7 days), and delayed post-operative (3-12 months) periods. Spearman rank correlation coefficients and corresponding 95% confidence intervals were computed to describe the association between sodium levels and length of stay (LOS). Sensitivity analyses were conducted for outliers. Logistic regression was used to describe the associations between sodium levels and mortality and reported as odd ratios (OR) and the 95% confidence interval. All analyses were conducted using a two-tailed alpha level of 5%. Results: There were 89 patients included in the study. Pre-operative sodium levels had a weak negative association with pre-operative days in the hospital (r = -0.238; 95% CI -0.425, -0.029; p = 0.0256). Conversely, early post-operative sodium levels had a moderately strong positive association with post-operative length of stay in the hospital, (r = 0.448; 95% CI 0.262, 0.600; p < 0.0001). Average sodium levels from post-operative days 1, 3, and 7 were also associated with increased odds of mortality (OR=1.21; 95% CI 1.02-1.43; p= 0.0255) while the average of those from delayed measurements at months 3, 6, and 12 were not. Conclusion In our study population, immediate post-operative serum sodium levels had a positive correlation with mortality. However, delayed measurements at 3, 6, and 12 months, were not a predictor of outcomes post-LVAD implant.