A simultaneous electrocardiogram is important when electroencephalography is used in the evaluation of loss of consciousness.
This study examined the use of electroencephalograms (EEGs) in 2 groups of patients with loss of consciousness (LOC), and the importance of a simultaneous electrocardiogram (ECG). Each group consisted of 75 patients referred for EEG. Group 1 patients (LOC without an established cause) had no clear history of convulsive disorder, while group 2 patients (LOC secondary to epilepsy) did. In all patients, it was ascertained if any previous cardiac investigations had been performed. All patients had an EEG performed with a simultaneous ECG. In addition to reporting the EEG, the neurologist reviewed the ECG rhythm and QRS morphology from the strip recording in an attempt to use this as a cardiac screening test. A cardiologist with the availability of all strip recordings and a subsequent 12 lead ECG reviewed his findings. The ECG was classified as significantly abnormal (potentially capable of causing syncope) in 17% of group 1 patients and 5% of group 2. The neurologist, using the simultaneous ECG strip recording only, correctly identified 14 of the 17 significantly abnormal ECGs (84%) and 127 of the 133 normal cases. In most cases, this was the only ECG evaluation as the EEG was performed without any prior cardiac investigation in 53% of group 1 patients and 92% of group 2. In conclusion, the EEG was often used as an initial investigation in these patients with LOC. A simultaneous ECG strip enabled the neurologist to detect most patients with significantly abnormal ECGs or rhythm. This will allow appropriate early cardiac review of these patients.