Abstract 10885: Preoperative Hyponatremia Potentiates the Effects of Left Ventricular Dysfunction on Mortality after Cardiac Surgery
Background LV dysfunction and preoperative hyponatremia are independently associated with increased mortality after cardiac surgery. However, the interactions between these two risk factors have not been studied. Thus, we evaluated the interaction of low LVEF (<40%) and preoperative hyponatremia (Na <135 mEq/l) with mortality and morbidity in patients undergoing cardiac surgery.
Methods From 2005 to 2008, 2247 patients had cardiac surgery at our institution (CABG in 45%, Valve in 13%, CABG-valve in 13%, and other in 29%). Patients were divided into four groups based on EF and sodium levels. The interaction of preoperative hyponatremia and EF with hospital complications, length of hospital stay, and mortality was studied using logistic and Cox regression analysis.
Results 69% of patients had normal EF. 18% of normal EF and 35% of low EF patients had hyponatremia. Hyponatremic patients had higher NYHA class 3-4 and higher EuroSCORE irrespectively of their EF. Hyponatremia was associated with increased incidence of operative and postoperative (infectious, pulmonary, renal) complications, length of hospital stay, early and late mortality and decreased 1- and 3-year survival in patients with both normal and low EF (table). After adjusting for baseline and procedure variables, hyponatremia was associated with increased LOS for normal EF (multiplier 1.18, CI 1.09-1.27, p<0.001) and low EF (multiplier 1.13, CI 1.03-1.24, p=0.01), need for dialysis for normal EF (OR 2.16, CI 1.08-4.32, p=0.03), and a 51% increase in the risk of mortality for low EF (OR 1.51, CI 1.02-2.24, p=0.04) and a 75% increase in the risk of mortality for normal EF (OR 1.75, CI 1.22-2.51, p=0.002).
Conclusions Hyponatremia is more common in patients with low EF before cardiac surgery. Preoperative hyponatremia potentiates the adverse effects of low EF on outcomes and it is also associated with increased mortality, length of hospital stay, and postoperative complications in normal EF patients.
- © 2011 by American Heart Association, Inc.