Retrospective Analysis of ECG Changes and Arrhythmias in Patients With Profound Hyponatremia

Inclusion Criteria: * Adult patients ≥18 years of the Emergency Department of the University Hospital of Cologne/Germany * Plasma sodium ≤125 mmol/L in the admission blood sample and ≥ 130 mEq/L in a subsequent sample obtained during inpatient care. * 12-lead-ECG on admission and a second ECG during inpatient care after resolution of profound hyponatremia. Exclusion Criteria: * Lack of follow-up sodium analyses within the first 24 hours after admission * initial blood glucose \>300 mg/dL * Moderate or severe hypokalemia (potassium level \< 3 mmol/L) * Moderate or severe hyperkalemia (potassium level \> 6 mmol/L) * Pacemaker dependency with ventricular pacing * Relevant structural heart disease * Severe ischemic cardiomyopathy with an EF \< 35% * Untreated severe aortic valve stenosis * Dilated cardiomyopathy (DCM) * Hypertrophic cardiomyopathy (HCM) * Arrhythmogenic right ventricular cardiomyopathy (ARVC) * Infiltrative cardiomyopathy * Ion channel disease