Seizure Duration and ECT Remission: Registry Study from Sweden

 Out on PubMed, from investigators in Sweden, is this study:

Seizure Duration and Electroconvulsive Therapy in Major Depressive Disorder.

Gillving C, Ekman CJ, Hammar Å, Landén M, Lundberg J, Movahed Rad P, Nordanskog P, von Knorring L, Nordenskjöld A.JAMA Netw Open. 2024 Jul 1;7(7):e2422738. doi: 10.1001/jamanetworkopen.2024.22738.PMID: 39052292

The abstract is copied below:

Importance: Electroconvulsive therapy (ECT), wherein a generalized epileptic seizure is induced, is a treatment for major depressive disorder (MDD). Currently, it is unclear whether there is an association between seizure length and treatment outcome.

Objective: To explore the association between seizure duration, potential confounding variables, and ECT treatment outcome.

Design, setting, and participants: This population-based cohort study obtained data from the Swedish National Quality Register for ECT. Patients treated for unipolar MDD with unilateral electrode placement between January 1, 2012, and December 31, 2019, were included. The electroencephalographic (EEG) seizure duration from the first ECT treatment session for each patient was used for analysis. Data analyses were performed between March 2021 and May 2024.

Main outcomes and measures: The primary outcome was remission, defined as a cutoff score of less than 10 points on the self-assessment version of the Montgomery-Åsberg Depression Rating Scale within 1 week after ECT. Multivariate logistic regression analysis was performed to calculate odds ratios (ORs) between different seizure duration groups. Furthermore, the associations between concomitant use of pharmacological treatments, seizure duration, and remission rate were explored.

Results: Among the 6998 patients included, 4229 (60.4%) were female and the mean (SD) age was 55.2 (18.6) years. Overall, 2749 patients (39.3%) achieved remission after ECT. Patients with EEG seizure duration of 60 to 69 seconds had the highest remission rates compared with patients with seizure duration of less than 20 seconds (OR, 2.17; 95% CI, 1.63-2.88; P < .001). Anticonvulsant medications were associated with shorter seizure duration (eg, lamotrigine: β coefficient [SE], -6.02 [1.08]; P < .001) and lower remission rates (eg, lamotrigine: adjusted OR, 0.67; 95% CI, 0.53-0.84; P < .001).

Conclusions and relevance: This study found an association between seizure length and remission from MDD. Use of anticonvulsant medication during ECT was associated with shorter seizure duration and lower remission rates after ECT.

The article is here.
And from the text:








This is a very important dataset and much kudification is due our Swedish colleagues, led by Dr. 
Nordenskjöld.
It stands to reason that if the seizure is the critical part of ECT, "better" seizures lead to better outcomes.
BUT this is a very complicated issue, the relationship is not a tight one at the individual patient level, and these data have many significant limitations: they are from the first ECT session only, this is only RUL ECT, the stimulus dosing method is not fully described, and the endpoint of "remission" one week after ECT is imperfect. 
The first treatment in the ECT series is distinct from the others: its seizure is often the longest, and contributes most to the lowering of depression scale scores. Seizures elicited near seizure threshold (ST) are often very long; the field is only recently coming to the understanding that increasing stimulus dose leads to shorter seizures. So there's the paradox (in these data) of higher stimulus charge being more effective despite the association with shorter seizures. There are other paradoxes, but a complete discussion is beyond the scope of this blog entry. 
This study adds another, but not a final, word to the longstanding, ongoing discussion of the importance of seizure duration in ECT.
Clinically, it is wise to aim for adequately long, robust EEG seizures in ECT, but if the patient is getting well on schedule, it matters little what the seizures look like or how long they are.

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