High serum potassium level is associated with successful electrical cardioversion for new-onset atrial fibrillation in the intensive care unit: A retrospective observational study

Electrical cardioversion (ECV) is a potentially life-saving treatment for haemodynamically unstable new-onset atrial fibrillation (AF); however, its efficacy is unsatisfactory. We aimed to elucidate the factors associated with successful ECV and prognosis in patients with AF. This retrospective observational study was conducted in two mixed intensive care units (ICUs) in a university hospital. Patients with new-onset AF who received ECV in the ICU were enrolled. We defined an ECV session as consecutive shocks within 15 minutes. The success of ECV was evaluated five minutes after the session. We analysed the factors associated with successful ECV and ICU mortality. Eighty-five AF patients who received ECV were included. ECV was successful in 41 (48%) patients, and 11 patients (13%) maintained sinus rhythm until ICU discharge. A serum potassium level ≥3.8 mol/L was independently associated with successful ECV in multivariate analysis (odds ratio (OR), 3.13; 95% confidence interval (CI), 1.07–9.11; p = 0.04). Maintenance of sinus rhythm until ICU discharge was significantly associated with ICU survival (OR 9.35; 95% CI 1.02–85.78, p = 0.048). ECV was successful in 48% of patients with new-onset AF developed in the ICU. A serum potassium level ≥3.8 mol/L was independently associated with successful ECV, and sinus rhythm maintained until ICU discharge was independently associated with ICU survival. These results suggested that maintaining a high serum potassium level may be important when considering the effectiveness of ECV for AF in the ICU.