Serum potassium level is associated with cardiac arrhythmias and in-hospital mortality in patients with acute myocardial infarction

Background: Dyskalemia is a risk factor for poor prognosis in patients with acute myocardial infarction (AMI). There is still controversy regarding the optimal level of serum potassium in these patients. Method: We studied patients who were admitted with a recorded diagnosis of AMI retrospectively. Using multivariable logistic regression models, we assessed the relationship between admission serum potassium concentration (SPC) and the risk of in-hospital mortality and arrhythmias. Potassium levels were divided as follows: K+< 3.5; K+= 3.5-<4.0; K+= 4.0-<4.5; K+=4.5-5.0; k+> 5.0mmol/l; with K+= 4.0-<4.5mmol/l as reference group. Results: Of the 2698 patients included in this study, 38.1% were diagnosed with ST-segment elevation myocardial infarction (STEMI) and 60.3% with non ST-segment elevation myocardial infarction (NSTEMI). Frequency of patients with diabetes, renal failure, atrial fibrillation and 2nd/3rd degree AV block were higher in theK+>5.0mmol/l group and those with Hypertension and ventricular arrhythmia in the K+<3.5mmol/l group. A U-shaped association between admission SPC and in-hospital mortality was observed (OR 1.30; 95% CI: 0.50, 7.35) and (OR 1.21; 95% CI: 0.55, 4.38) in patients with K+>5.0mmol/l and K+<3.5mmol/l respectively. However patients with AMI and diabetes demonstrated a J shaped curve with the highest in-hospital mortality observed in the K+>5.0mmol/l group. The lowest risk for in-hospital mortality was observed in K+=3.5<4.0(OR 0.82; 95% CI: 0.53, 2.19) followed by K+= 4.0-<4.5mmol/l. Conclusion: Potassium levels between 4.0 and 4.5mmol/l was relatively safe but not superior to levels between 3.5 and 4.0mmol/l. It might be beneficial to target SPC between 3.5 and 4.0mmol/l.