In-hospital ventricular fibrillation and its relation to serum potassium.

Serum potassium (S-K) has been related to the incidence of ventricular fibrillation (VF) before admission to, and during observation in a coronary care unit (CCU). The series comprises 1315 patients. Acute myocardial infarction (AMI) was diagnosed in 537 patients. VF occurred in 46 patients. Fourteen of these had their VF before admission to the CCU. The incidence of VF within 12 h after CCU admission (early VF) was significantly raised (p less than 0.01) in patients with an initial S-K less than 3.9 mmol . l-1. In this group, the incidence of early VF in all patients and in those with AMI amounted to 3.0 and 5.4%, respectively. Corresponding figures in patients with an initial S-K of 3.9 mmol . l-1 or above were 0.6 and 1.5%. Thus, a near 5-fold increase in the incidence of early VF was observed with a S-K below 3.9 mmol . l-1. Patients with VF occurring later than 12 h after admission had significantly higher S-K values than those with early VF. In AMI, the risk of primary and secondary VF seemed to be equally increased with low initial S-K values. There was a strong correlation between myocardial infarction size and the risk of VF. No relationship, however, was noted between infarction size and initial S-K.