Prevalence of late potentials on signal-averaged ECG in patients with psychiatric disorders

BackgroundSudden cardiac death (SCD) occurs three times more often in psychiatric patients than in the general population. QRS fragmentation (QRSfr) and signal-averaged electrocardiography (SAECG) are simple, inexpensive, readily available tools for detecting the presence of abnormal depolarization and late potentials (LPs) in these patients, a result of either the underlying disease or treatment.MethodsFrequency of LP detection by SAECG and QRSfr was studied in 52 psychiatric patients and compared with 30 healthy (without known structural heart disease or occurrence of ventricular arrhythmia) controls. Patients were then prospectively followed up and incidence of SCD was recorded.ResultsLP prevalence was significantly higher in patients than in controls (16/52-31% vs 2/30-7%, p = 0.012), while QRSfr was similar between these two groups (p = 0.09). Of the LP presence criteria, the root mean square value at terminal 40 msec of the QRS (RMS40) was significantly lower in patients (32 μV, SD = 19 μV, vs 46 μV, SD = 32 μV, p = 0.015). Among patients, no differences were noted between the LP positive and negative groups regarding age, sex, number of medications, class of antipsychotics and defined daily doses. Mean follow-up was 46 months (SD = 11) and during it 3 patients suffered SCD. Although 2 SCD victims had both LPs and QRSfr concurrently present, neither of them, nor their simultaneous presence could definitely account for the events.ConclusionsLP prevalence in psychiatric patients was significantly higher than in controls. SAECG performance was feasible in all cases and constitutes a readily available tool for assessing myocardial electrophysiological alterations in this patient group.