The effect of serum potassium level on in-hospital and long-term mortality in ST elevation myocardial infarction

Current studies evaluating the effect of serum potassium levels on mortality in patients with ST elevation myocardial infarction (STEMI) are lacking. We analyzed retrospectively 3760 patients diagnosed with STEMI. Mean serum potassium levels were categorized accordingly: < 3.0, 3.0 to < 3.5, 3.5 to < 4.0, 4.0 to < 4.5, 4.5 to < 5.0, 5.0 to < 5.5, and ≥ 5.5 mEq/L. The lowest mortality was determined in patients with serum potassium level of 4 to < 4.5 mEq/L whereas mortality was higher in patients with serum potassium levels of ≥ 5.0 and < 3.5 mEq/L. In a multivariable Cox-proportional regression analysis, the mortality risk was higher for patients with serum potassium levels of ≥ 5 mEq/L [hazard ratio (HR), 2.11; 95% confidence interval (CI) 1.23-4.74 and HR, 4.20; 95% CI 1.08-8.23, for patients with potassium levels of 5 to < 5.5 mEq/L and ≥ 5.5 mEq/L, respectively]. In-hospital and long-term mortality risks were also higher for patients with serum potassium levels of ≤ 3.5 mEq/L. Conversely, ventricular arrhythmias were higher only for patients with serum potassium level of ≤ 3.5 mEq/L. Furthermore, a significant relationship was found between the patient with serum potassium levels of ≤ 3.5 mEq/L and ventricular arrhythmias.