Endpoint of ECT-induced elevation in heart rate

Changes in the heart rate during electroconvulsive therapy (ECT) reflect seizure activity at a deeper bl ain site than shown by electroencephalography and motoric activity. Accordingly, such changes may provide additional information that is helpful in the evaluation of treatment quality. One basic measurement of heart rate change is the duration of ECT-induced tachycardia. In a prospective study, the electrocardiographic ECT records of 24 patients were rated for the abruptness of the endpoint of the seizure-induced elevation in heart rate; 19 showed abrupt endpoints and 5 showed gradual endpoints. The baseline heart rate of patients with abrupt endpoints (88 SD [standard deviation] 10 beats/min) was significantly lower (p = 0.00001) than those with gradual endpoints (118 SD 12 beats/min). A threshold occurred at a baseline heart rate of 100 beats/min, with abrupt endpoints below and gradual endpoints above. The data suggest that patients with low baseline heart rates might be likely to show bradyarrhythmia during the treatment, and corresponding precautions might be considered.