Electrolyte disturbances are common after cardiac surgery involving cardiopulmonary bypass (CPB) and may influence postoperative outcomes. Although postoperative atrial fibrillation (POAF), atelectasis, and pleural effusion are frequently encountered complications, the extent to which electrolyte imbalances contribute to their development remains unclear. We investigate the association between perioperative electrolyte imbalances and the incidence of POAF, atelectasis, and pleural effusion in patients undergoing open-heart surgery with CPB. This retrospective descriptive study analyzed 1392 adult patients who underwent elective coronary artery bypass grafting (CABG), valve surgery, or aortic repair at Herzliya Medical Center between January 2017 and August 2023. Serum electrolyte levels (sodium, potassium, magnesium, and phosphorus) were recorded during the immediate postoperative period. Complications were defined using clinical and imaging criteria. Associations between electrolyte abnormalities and complications were evaluated using Chi-squared tests, independent t -tests, and logistic regression models. The most common complication was POAF (249 cases, 17.9%); postoperative pulmonary complications were observed in 124 (8.9%) cases. Hyponatremia was not associated with complications, but hypernatremia was associated with complications in 24% of patients, while only 8% of patients without hypernatremia developed complications (odds ratio OR=3.500, 95% confidence interval CI: 1.673–7.323, P <0.001). Hypokalemia was not associated with pulmonary complications, but hyperkalemia was significantly associated with complications (OR=3.043, 95%CI: 1.590–5.794, P= 0.002). Hyperphosphatemia was also independently associated with an elevated risk of atelectasis and pleural effusion (OR=1.731, 95%CI: 1.185–2.529, P <0.004). Hypermagnesemia showed a significant difference (12.4% vs. 6.5%) in terms of pulmonary complications (OR=2.038, 95%CI: 1.404–2.958, P <0.001). In contrast, no significant associations were observed between electrolyte imbalances and POAF, although hyperphosphatemia showed a borderline association ( P =0.051). Electrolyte imbalances—particularly involving potassium, sodium, and phosphorus—are strongly associated with postoperative pulmonary complications following cardiac surgery. These findings highlight the importance of vigilant perioperative electrolyte monitoring and targeted correction protocols to mitigate the risk of atelectasis and pleural effusion. The role of electrolyte disturbances in the development of POAF appears less pronounced, suggesting a multifactorial etiology.
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