Background Iatrogenic long QT syndrome is an adverse effect commonly described in psychiatry.

Purpose To correlate real observations from clinical practice with the predictions.

Materials and methods A prospective study was performed analysing patients admitted to the psychiatric ward over two months. Exclusion criteria were: patients suffering from cardiopathy, hypokalaemia, and/or patients not participating in the treatment. The following data were collected: age, sex, body mass index (BMI), smoking habits, QTC interval in the ECG when admitted, and prescriptions of psychoactive and non-psychoactive drugs. Each drug prescribed was given a score established for the purpose, based on the four groups provided by an updated table (www.qtdrugs.com). QTC segment in the ECG not affected (0 points), conditional risk existed (1 point), with chances of appearance (2 points), with high risk of appearance (3 points). The QT interval was considered short <430 ms, borderline 430–460 ms, or long >460 ms.

Results 64 patients (50% women) with an average age of 51.53 years (SD = 17.7), 31% smokers and with average BMIs of 26.8. The patients had an average of 3.18 prescriptions of psychoactive drugs, 43% of which were described in the literature as possibly causing a change in the QT interval. 78% of patients had a short QT interval and average scores of 2.66 points (SD = 1.68). 15% showed a borderline QT with an average of 1.8 points (SD = 1.47), and 7% of them had a long QT, reaching averages of 1.25 (SD = 1.5).

Conclusions A high percentage of patients were treated with drugs that, theoretically, could increase the QT interval. However, we did not find a correlation between real and predicted values.

No conflict of interest.