QTc prolongation and clozapine: fact or artefact?

Antipsychotics in routine treatment are minor contributors to QT prolongation compared to genetics and age

BACKGROUND

Drug-induced prolongation of cardiac repolarization limits the treatment with many psychotropic drugs. Recently, the contribution of polygenic variation to the individual duration of the QT interval was identified.

AIMS

To explore the interaction between antipsychotic drugs and the individual polygenic influence on the QT interval.

METHODS

Retrospective analysis of clinical and genotype data of 804 psychiatric inpatients diagnosed with a psychotic disorder. The individual polygenic influence on the QT interval was calculated according to the method of Arking et al.

RESULTS

Linear regression modelling showed a significant association of the individual polygenic QT interval score (ß_std = 0.176, p < 0.001) and age (ß_std = 0.139, p < 0.001) with the QTc interval corrected according to Fridericia's formula. Sex showed a nominal trend towards significance (ß_std = 0.064, p = 0.064). No association was observed for the number of QT prolonging drugs according to AZCERT taken. Subsample analysis (n = 588) showed a significant association of potassium serum concentrations with the QTc interval (ß_std = -0.104, p = 0.010). Haloperidol serum concentrations were associated with the QTc interval only in single medication analysis (n = 26, ß_std = 0.101, p = 0.004), but not in multivariate regression analysis. No association was observed for aripiprazole, clozapine, quetiapine and perazine, while olanzapine and the sum of risperidone and its metabolite showed a negative association.

CONCLUSIONS

Individual genetic factors and age are main determinants of the QT interval. Antipsychotic drug serum concentrations within the therapeutic range contribute to QTc prolongation on an individual level.

Noncompaction and Dilated Cardiomyopathy in a Patient with Schizophrenia

Objectives. Psychosis and left ventricular hypertrabeculation (or noncompaction) (LVHT) have not been described in the same patient. Here we report a patient with a long-term history of schizophrenia who was later diagnosed with dilated cardiomyopathy (dCMP) and LVHT. Case Report. A 47-year-old Caucasian male developed nondifferentiated schizophrenia at the age of 26 y. Since the age of 33 y he was regularly drinking alcohol. At the age of 47 y he developed heart failure. Transthoracic echocardiography showed an enlarged left ventricle, reduced systolic function, and surprisingly LVHT in the apical segment. Additionally, the left atrium was enlarged, the right ventricular cavities were mildly enlarged, and there were pulmonary hypertension and a small pericardial effusion. Cardiac MRI confirmed the echocardiographic findings. Since coronary angiography was normal, dilated cardiomyopathy was additionally diagnosed. Since he was taking clozapine during years, dilated cardiomyopathy could be due to not only alcohol consumption but also the long-term neuroleptic medication. Conclusions. LVHT may be associated with nondifferentiated psychosis. Management of LVHT is challenging in patients with psychosis due to poor compliance and adherence of these patients. Patients with LVHT and psychosis need particular attention since they usually take cardiotoxic drugs for a long time, which may further deteriorate the prognosis of LVHT.

The cardiac safety of aripiprazole treatment in patients at high risk for torsade: a systematic review with a meta-analytic approach

RATIONALE

Certain antipsychotics increase the risk of heart rate-corrected QT (QTc) prolongation and consequently Torsades de Pointes (TdP) and sudden cardiac death (SCD). Drug-induced Brugada syndrome (BrS) is also associated with SCD. Most SCDs occur in patients with additional cardiac risk factors.

OBJECTIVES

Aripiprazole's cardiac safety has not been assessed in patients at high risk for torsade, where QTc prolongation risk is highly increased.

METHODS

MEDLINE, Embase, and The Cochrane Library were searched for preclinical, clinical, and epidemiological studies. Eligible studies were reviewed and cardiac safety data were extracted. Continuous and dichotomous QTc data were used in the meta-analysis.

RESULTS

Preclinical studies suggested that aripiprazole has limited affinity for the delayed rectifier potassium current. TdP was reported in two case reports and SCD was reported in one case report and one case series. No clinical studies assessing aripiprazole's cardiac safety in patients at high risk for torsade were found. No thorough QT (TQT) study with aripiprazole was found. The meta-analysis revealed that the mean ΔQTc interval was decreased with aripiprazole and QTc prolongation risk was lower compared with placebo and active controls. Epidemiological studies linked aripiprazole to weak/moderate torsadogenicity. No studies were found associating aripiprazole with BrS suggesting low affinity for the fast sodium current.

CONCLUSIONS

Aripiprazole is a low-risk antipsychotic regarding cardiac safety in healthy patients. However, baseline and steady state electrocardiogram is recommended in patients at high risk for torsade due to marked QTc prolongation, absence of a TQT study, and lack of data in this group.

Cardiac effects of sertindole and quetiapine: analysis of ECGs from a randomized double-blind study in patients with schizophrenia

The QT interval is the most widely used surrogate marker for predicting TdP; however, several alternative surrogate markers, such as Tpeak-Tend (TpTe) and a quantitative T-wave morphology combination score (MCS) have emerged. This study investigated the cardiac effects of sertindole and quetiapine using the QTc interval and newer surrogate markers. Data were derived from a 12 week randomized double-blind study comparing flexible dosage of sertindole 12-20mg and quetiapine 400-600mg in patients with schizophrenia. ECGs were recorded digitally at baseline and after 3, 6 and 12 weeks. Between group effects were compared by using a mixed effect model, whereas assessment within group was compared by using a paired t-test. Treatment with sertindole was associated with QTcF and QTcB interval prolongation and an increase in MCS, T-wave asymmetry, T-wave flatness and TpTe. The mean increase in QTcF from baseline to last observation was 12.1ms for sertindole (p<0.001) and -0.5ms for quetiapine (p=0.8). Quetiapine caused no increase in MCS, T-wave asymmetry, T-wave flatness or TpTe compared to baseline. In the categorical analysis, there were 11 patients (9.6%) receiving quetiapine who experienced more than 20ms QTcF prolongation compared with 36 patients (33.3%) in the sertindole group. Sertindole (12-20mg) was associated with moderate QTc prolongation and worsening of T-wave morphology in a study population of patients with schizophrenia. Although, quetiapine (400-600mg) did not show worsening of repolarization measures some individual patients did experience significant worsening of repolarization. Clinical Trials NCT00654706.

QT dynamics during treatment with sertindole

OBJECTIVES

Sertindole is a nonsedating atypical antipsychotic drug with low propensity to cause extrapyramidal side effects but it has been associated with a 20 ms QTc prolongation and increased risk of cardiac events. It is uncertain whether this drug-induced increase in cardiac risk might also be revealed by dynamic measures of the QT interval such as the ratio of QT variability to heart rate variability (variability ratio [VR]). The aim of this study was to investigate the effect of sertindole on QT dynamics.

METHODS

QTc and the VR were assessed in an observational study using 24-hour Holter monitoring at baseline and after 3 weeks of treatment with sertindole 16 mg. The VR was calculated by dividing the standard deviation of QT intervals with the standard deviation of heart rates. Outcome measures were compared using paired t-test.

RESULTS

A total of 18 patients participated in the study, two were excluded from further analysis due to low amplitude of the T-wave. When patients were shifted to sertindole, the VR increased from 0.192 (SD 0.045) to 0.223 (SD 0.061), p = 0.02. The QTcF interval increased from 388 (SD 16) to 403 ms (SD 14), p = 0.002. There was no difference in heart rate 78 bpm (SD 8) versus 80 bpm (SD 10), p = 0.3 or heart rate variability (SDNN) 127 (SD 40) versus 115 ms (SD 45), p = 0.4.

CONCLUSION

Sertindole was associated with 19 ms QTc prolongation and an increased ratio of QT variability to heart rate variability. Both measures may contribute to the increased cardiovascular mortality found with sertindole.

QTc interval prolongation and torsade de pointes associated with second-generation antipsychotics and antidepressants: a comprehensive review

We comprehensively reviewed published literature to determine whether it supported the link between corrected QT (QTc) interval prolongation and torsade de pointes (TdP) for the 11 second-generation antipsychotics and seven second-generation antidepressants commonly implicated in these complications. Using PubMed and EMBASE, we identified four thorough QT studies (one each for iloperidone, ziprasidone, citalopram, and escitalopram), 40 studies specifically designed to assess QTc interval prolongation or TdP, 58 publications based on data from efficacy and safety trials, 18 toxicology studies, and 102 case reports. Thorough QT studies, QTc prolongation-specific studies, and studies based on efficacy and safety trials did not link drug-associated QTc interval prolongation with TdP. They only showed that the drugs reviewed caused varying degrees of QTc interval prolongation, and even that information was not clear and consistent enough to stratify individual drugs for this risk. The few toxicology studies provided valuable information but their findings are pertinent only to situations of drug overdose. Case reports were most informative about the drug-QTc interval prolongation-TdP link. At least one additional well established risk factor for QTc prolongation was present in 92.2 % of case reports. Of the 28 cases of TdP, six (21.4 %) experienced it with QTc interval <500 ms; 75 % of TdP cases occurred at therapeutic doses. There is little evidence that drug-associated QTc interval prolongation by itself is sufficient to predict TdP. Future research needs to improve its precision and broaden its scope to better understand the factors that facilitate or attenuate progression of drug-associated QTc interval prolongation to TdP.