2-1-102. Changes in corrected QT interval during electroconvulsive therapy

Abstract

Corrected QT interval (QTc) prolongation can trigger ventricular arrhythmia, including torsade de pointes (TdP). A QTc greater than 500 ms is considered to provide a high risk of TdP. Herein, we evaluated the risk of TdP during electroconvulsive therapy (ECT) using QTc. Twenty-two patients who underwent ECT were included. QTc were calculated with Hodges formula to avoid overcorrection of heart rate in a total of 201 ECT sessions. Baseline QTc was averaged over 30 s before stimulus onset. A QTc >457 ms was classified as a significant prolongation, and >500 ms as marked prolongation. The number of significant and marked QTc prolongations at baseline and the post-stimulus period were counted. At baseline, significant QTc prolongation was observed in 15 of 201 ECTs, while no patients showed marked prolongation. For post-stimulation, significant QTc prolongation and marked QTc prolongation was observed in 109 and 5 out of 201 ECT sessions, respectively. All the five marked QTc prolongations during post-ECT stimulation followed significant baseline QTc prolongation. These data suggest that a prolonged pre-stimulus QTc may be a risk factor of post-stimulus TdP in ECT.