Prolonged QT interval in acute psychotic patients.

Some recent clinical studies indicate that hypokalemia is characteristic for acute psychotic patients at the time of emergency admission. As hypokalemia is one of the major causes for prolonged QT interval, it was hypothesized that acute psychotic patients could show prolonged QT interval. Sixty-seven drug-free, acute psychotic patients were evaluated for corrected QT (QTc) interval, as well as demographic and clinical characteristics at the time of emergency admission. The mean QTc interval of psychiatric emergency patients was prolonged, and the mean QTc interval of psychiatric emergency patients was longer than that of psychiatric outpatients (t=5.20, P<0.0001). Age- or gender-related difference, circadian fluctuation of QT interval, medication, concomitant disease, obesity, and serum electrolytes except potassium were not major causes. There was a significant negative correlation as evidenced by a coefficient of correlation of -0.28 (P<0.05). As psychiatric emergency patients often receive parenteral antipsychotics, which may have adverse effects on prolonged QT interval, paying attention to QT interval might have some clinical significance on emergency admission.