Electrocardiographic and cardiovascular effects of subconvulsive stimulation during titrated right unilateral ECT

The American Psychiatric Association Task Force on ECT has recommended that electroconvulsive therapy (ECT) stimuli be dosed at "moderately suprathreshold" intensities. Empiric estimation of the convulsive threshold by stimulus dose titration may expose the patient to subconvulsive stimuli, and subconvulsive stimuli have been reported by some to carry serious cardiovascular risk. This study examines the electrocardiographic (ECG) and cardiovascular effects of subconvulsive stimuli. Forty consecutive inpatients (29 women, 11 men; mean age 68 years) with major depression received subconvulsive stimuli during titrated, right unilateral (RUL) ECT. Successively larger stimuli were administered until a convulsion began. The effects of subconvulsive stimuli on the ECG, heart rate (HR), and blood pressure (BP) were assessed with multivariate repeated measures analysis. Subconvulsive stimuli prolonged the R-R interval and decreased HR compared with baseline values immediately before the subconvulsive stimulus, but the changes were of questionable clinical significance. BP was not changed. In conclusion, subconvulsive stimuli are well tolerated in the context of titrated RUL ECT. If stimulus dose titration proves to be useful in optimizing efficacy with fewer cognitive side effects, then cardiovascular considerations should not be an obstacle in the application of stimulus dose titration in most patients.