P1395The role of hyponatremia in the development of atrial fibrillation after cardiac surgery

Abstract

Abstract Background. Atrial fibrillation (AF) is one of the most common complication after cardiac surgeries. Age, valvular heart disease, heart failure, chronic obstructive pulmonary disease and a history of AF are well known risk factors for postoperative AF. On the other hand, hyponatremia is also a frequent disorder in patients undergoing cardiac surgery but its relationship with AF has not been studied. Purpose. We evaluated the impact of hyponatremia on the incidence of postoperative AF in patients undergoing cardiac surgery with cardiopulmonary bypass. Methods. The retrospective study included case history of 222 patients (174 men and 48 women, median age 64.5 [range 58.0; 69.0] years) who underwent cardiac surgery with cardiopulmonary bypass between January 2015 and December 2018.  In all patients intraoperative sodium level was analyzed. Hyponatremia was defined as serum sodium level < 135 mmol/l. Primary outcome was the episode of AF in postoperative period. Results. The incidence of postoperative AF was 18.9% (95% confidence interval (CI) 14.1-24.3 P = 0.05). Patients with AF more often had obesity, diabetes mellitus and a history of myocardial infarction and were more likely to perform combined surgery compared to non-AF patients (all Ps < 0.05). The prevalence of hyponatremia was significantly higher among AF group compared with non-AF (95.2% versus 77.8%, P = 0.017). Hyponatremia was the independent risk factors of postoperative AF in Cox regression models adjusted for covariates (odds ratio 5.31; 95% CI 1.42-18.7; P = 0.017). Conclusion.  In this analysis serum sodium level was closely associated with the risk of AF. These findings suggest that hyponatremia may cause the development of postoperative AF in patients undergoing cardiac surgery with cardiopulmonary bypass.