Kim YM, Park JE, Hwang SY, et al. - Researchers conducted a single-center, retrospective observational study of patients with pulseless electrical activity (PEA) cardiac arrest with the aim to determine the correlation between hyperkalemia and wide QRS complex in these patients. Among 617 assessed patients, a total of 111 episodes were analyzed in the wide QRS group and 506 episodes in the narrow QRS group. Significantly higher potassium level was observed in the wide QRS group than the narrow QRS group. Observations revealed significant correlation of wide QRS PEA as an initial cardiac rhythm with hyperkalemia in cardiac arrest patients.