Signal-averaged ECG in patients with antidepressant therapy

Late Potentials and Early Repolarisation Are Associated With Serious Mental Illness and May Portend Increased Arrhythmic Risk

BACKGROUND

Patients with serious mental illness (SMI) have an increased risk of sudden death. Higher rates of signal-averaged electrocardiogram (SAECG) abnormal late potentials (LP), which may be a predictor of sudden death risk, have been shown in patients with schizophrenia. We aimed to assess the prevalence and predictors of electrocardiograph (ECG) and SAECG abnormalities in a mixed SMI population.

METHODS

Consecutive consenting inpatients with SMI had 12-lead ECG and SAECG recorded in addition to demographics, diagnoses and medications. Standard criteria for abnormal SAECG were applied. Multivariate regression analysis was performed to determine predictors of SAECG abnormalities including diagnoses, body mass index, ECG parameters, psychotropic medication use, and medications associated with Long QT or Brugada syndromes.

RESULTS

Eighty (80) patients, 49% male, mean age 39±17 years were included. SAECG criteria abnormality for 1, 2 or 3 criteria were seen in 19, 3 and 5 cases (34% in total) respectively. Early repolarisation pattern was seen in 19% of patients. SAECG abnormality was associated with male gender (OR 7.3; 95% CI 2.3-23.4), and schizophrenia/schizoaffective disorder diagnosis (OR 7.4; 95% CI 1.9-29.0), but not with medication type or dose.

CONCLUSIONS

In the mixed SMI population studied, there was a high rate of SAECG-detected late potentials (34%) and early repolarisation pattern (19%). Schizophrenia/schizoaffective disorder diagnosis was the strongest multivariate predictor identified. Further studies are needed to define the mechanism and significance of these cardiac abnormalities in SMI patients.

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

BACKGROUND

Sudden 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.

METHODS

Frequency 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.

RESULTS

LP 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 40msec of the QRS (RMS40) was significantly lower in patients (32μV, SD=19μV, vs 46μV, SD=32μV, 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 46months (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.

CONCLUSIONS

LP 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.

Sudden death of cardiac origin and psychotropic drugs

Mortality rate is high in psychiatric patients versus general population. An important cause of this increased mortality is sudden cardiac death (SCD) as a major side-effect of psychotropic drugs. These SCDs generally result from arrhythmias occurring when the posology is high and may attain a toxic threshold but also at dosages within therapeutic range, in the presence of risk factors. There are three kinds of risk factors: physiological (e.g., low cardiac rate of sportsmen), physiopathological (e.g., hepatic insufficiency, hypothyroidism) and "therapeutic" (due to interactions between psychotropic drugs and other medicines). Association of pharmacological agents may increase the likelihood of SCDs either by (i) a pharmacokinetic mechanism (e.g., increased torsadogenic potential of a psychotropic drug when its destruction and/or elimination are compromised) or (ii) a pharmacodynamical mechanism (e.g., mutual potentiation of proarrhythmic properties of two drugs). In addition, some psychotropic drugs may induce sudden death in cases of pre-existing congenital cardiopathies such as (i) congenital long QT syndrome, predisposing to torsade de pointes that eventually cause syncope and sudden death. (ii) A Brugada syndrome, that may directly cause ventricular fibrillation due to reduced sodium current through Nav1.5 channels. Moreover, psychotropic drugs may be a direct cause of cardiac lesions also leading to SCD. This is the case, for example, of phenothiazines responsible for ischemic coronaropathies and of clozapine that is involved in the occurrence of myocarditis. The aims of this work are to delineate: (i) the risk of SCD related to the use of psychotropic drugs; (ii) mechanisms involved in the occurrence of such SCD; (iii) preventive actions of psychotropic drugs side effects, on the basis of the knowledge of patient-specific risk factors, documented from clinical history, ionic balance, and ECG investigation by the psychiatrist.

Late potentials in the signal-averaged electrocardiogram in pre-pubertal children with ADHD, before and after methylphenidate treatment

Reports on sudden cardiac death (SCD) of children and adolescents treated with stimulant agents have raised concerns regarding the need for cardiovascular monitoring and risk stratification schedules. Cardiac ventricular late potentials (LPs) represent delayed ventricular activation that might predispose to fatal ventricular arrhythmias and SCD in cardiac patients. LPs have not previously been measured in children with attention deficit/hyperactivity disorder (ADHD). LPs were measured in 18 physically healthy ADHD children (5 girls and 13 boys, age 11.9 ± 2.5 years, treatment duration 2.6 ± 1.9 years) before and 2 h after oral methylphenidate administration. No significant changes were detected and LPs were found to be within normal ranges. In conclusion, this preliminary small-scale study suggests that methylphenidate in physically healthy children with ADHD was not associated with cardiac ventricular LPs, suggesting the safety of the agent in this age group.

Late potentials in the signal-averaged electrocardiogram in schizophrenia patients maintained on antipsychotic agents: a preliminary naturalistic study

In the present, preliminary, naturalistic study, cardiac ventricular late potentials (LPs), were measured in 33 physically healthy schizophrenia patients (13 - females and 26 - males, age - 45.5+/-8.8years) maintained on typical and atypical antipsychotic agents. These LPs represent delayed ventricular activation that might predispose to fatal ventricular arrhythmias and sudden cardiac death (SCD) in cardiac patients. Sixteen of the 33 patients ( approximately 48%) were found to be positive for LPs (compared to 3.7-6% in the general population). No association was found with any of the following: drug type, anti-cholinergic burden, daily dose of antipsychotic agents, age, gender, disease duration, QT(c) interval and QT dispersion. Further large-scale longitudinal prospective studies are warranted to substantiate our findings and to clarify their impact on the excess cardiac morbidity and mortality in schizophrenia patients.