Pre-operative serum potassium levels and peri-operative outcomes in patients undergoing cardiac surgery

Although potassium is critical for normal electro physiology, the associations between pre-operative serum potassium level and peri-operative adverse events such as arrhythmias in cardiac surgery have not been examined in detail. The objective of this study was to determine the prevalence of abnormal pre-operative serum potassium levels and whether such levels were associated with adverse peri-operative events in 50 patients undergoing coronary artery bypass grafting. Intra-operative and post-operative arrhythmias, the need for cardio-pulmonary resuscitation, cardiac death and death due to any cause prior to discharge from the post-operative intensive care unit were studied. The incidence for adverse outcome was 0.5% for death, 0.5% for cardiac death and 2% for cardio pulmonary resuscitation in patients with hypokalemia (serum potassium level < 3.5 meq. L-1). Hypokalemia was found to be a predictor of serious peri-operative (OR: 2.2; 95% CI: 1.2-4.1) and post-operative arrhythmias (OR: 1.7; 95% CI: 1.0-2.7). Pre-operative potassium repletion is low cost and low risk treatment measure and the data from this study suggests that screening and repletion be considered in patients scheduled for cardiac surgery.