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Preoperative Hypokalemia Associated with Increased Perioperative Arrhythmia

Should cardiac surgery be delayed when preoperative testing reveals hypokalemia? This study analyzed data from 2,402 patients undergoing elective coronary artery bypass graft surgery at 24 U.S. medical centers, of whom 70 (3 percent) had preoperative hypokalemia (defined as potassium levels below 3.5 mmol/l). Hypokalemia was associated with female sex, history of arrhythmias, hypertension, and use of diuretics.

During the perioperative period, 1,290 patients (54 percent) had arrhythmias, 498 (21 percent) of which were serious. Twenty-five of the hypokalemic patients had serious arrhythmias (36 percent; odds ratio, 2.2); hypokalemic patients had similar increases in risk for intraoperative arrhythmia and postoperative atrial fibrillation or flutter. Hypokalemia was also associated with a more than threefold increase in need for CPR, although this association became nonsignificant when other clinical data were considered in multivariate analyses.

Comment: Hypokalemia appears to lower patients' thresholds for developing arrhythmias during cardiac surgery. Even though interventional trials have not been performed to demonstrate the effect of aggressive treatment of hypokalemia before surgery, the safety and low cost of that strategy seem justifiable in patients scheduled for elective procedures.

— TH Lee

Published in Journal Watch General Medicine June 29, 1999

Citation(s):

Wahr JA et al. Preoperative serum potassium levels and perioperative outcomes in cardiac surgery patients. JAMA 1999 Jun 16 281 2203-2210.

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