Does higher cardiovascular response to ECT predict early antidepressant effect?

Background: Effects of diencephalic seizure generalization during ECT, e.g., cardiovascular response, may be relevant in indexing its therapeutic potency. A trend for greater rate pressure product (RPP=heart rate×systolic blood pressure) response to modified ECT in responders than in nonresponders is reported. Atropine used in modified ECT is known to increase RPP. This study examined if cardiovascular response during ECT with or without atropine predicts antidepressant effect. Methods: Twenty nine consenting, major depressive disorder patients received ECTs. Atropine premedication was randomly withheld in the second or third ECT session. RPP was recorded during ECT. Severity of depression was measured at twice weekly intervals. Results: Fifteen patients remitted at the end of 2 weeks. These early remitters had significantly higher poststimulus RPP than the rest in the ECT session without atropine but not so in the session with atropine. Cumulative poststimulus RPP predicted the early antidepressant response. Corresponding motor or EEG seizure durations were not associated with antidepressant effect. Limitations: Most patients continued to receive antidepressants. ECT stimulus laterality was not controlled. The study focussed on only short term antidepressant effects. Conclusions: RPP response to ECT recorded under no-atropine condition may reflect its physiological effects relevant to therapeusis and may have the potential to index seizure adequacy.