Hoppe LK, et al. - Researchers sought to provide the first systematic review and meta-analysis of observational studies on the association of abnormal serum potassium and cardiovascular outcomes. In the older general population, low serum potassium was associated with a 1.6-fold increased risk of supraventricular arrhythmias, however, high serum potassium was associated with increased cardiovascular mortality (CVM). Patients with acute myocardial infarction showed increased risk of ventricular arrhythmias for high serum potassium. They noted a U-shaped association with a composite cardiovascular outcome in hypertensive patients, with CVM in dialysis patients and with CVM in heart failure patients. In addition, only hyperkalemia was noted to be associated with an increased risk of a composite cardiovascular outcome in both dialysis and chronic kidney disease patients.