BACKGROUND: Electroconvulsive therapy (ECT) continues to be the most efficacious treatment for severe depression and other life-threatening acute psychiatric conditions. Treatment efficacy is dependent upon the induced seizure quality, which may be influenced by a range of treatment related factors. Recently, the time interval from anesthesia to the electrical stimulation (ASTI) has been suggested to be an important determinant of seizure quality.

METHODS: We measured ASTI in 73 ECT sessions given to 22 individual patients, and analyzed its influence on five seizure quality parameters (EEG seizure time, power, coherence, postictal suppression, and peak heart rate).

RESULTS: Longer ASTI was significantly associated with higher peak heart rate during the seizure (p = .003). After adjustment for confounders, the association continued to be significant, even after Bonferroni correction for multiple comparisons (p = .005). ASTI was not significantly associated with other seizure parameters.

LIMITATIONS: The relatively low number of sessions may lead to false negative findings. The study did not include clinical outcomes.

CONCLUSIONS: Longer ASTI is associated with higher peak heart rate; a phenomenon which is thought to reflect better seizure propagation to subcortical areas of the brain. The finding indicates that delay of stimulation after anesthesia could be a simple way of improving seizure quality and thereby the clinical effect of ECT.