[Initial serum potassium level in relation to cardiac arrhythmias in acute myocardial infarction (author's transl)].

In 565 patients with acute myocardial infarction admitted to a coronary care unit within 12 hours of the onset of symptoms, serum potassium level was determined on admission. The incidence of dysrhythmias occurring during the first 12 hours was referred to the initial serum potassium level. Hypopotassemia (less than or equal to 3.5 mmol/l) was seen in 9.2% and associated with a significantly higher incidence of ventricular arrhythmias in 33% as compared to 18% in the control group. Especially ventricular fibrillation was significantly more frequent in the hypokalaemic (14%) than in the normokalaemic (3%) patients (P less than 0.01). Hyperpotassemia (less than or equal to 5.1 mmol/l) was found in 6% with a higher incidence of second and third degree AV block and left-bundle branch block. This group was much more prone to severe haemodynamic complications and therefore had a bad prognosis with a high clinic mortality of 53%. There was no relation between supraventricular arrhythmias, sinuatrial bradyarrhythmias and intraventricular block other than left bundle branch block to serum potassium level.