Quetiapine-Induced Bradycardia Without QT Interval Prolongation in an Elderly Woman

Electrocardiographic monitoring for new prescriptions of quetiapine co-prescribed with acetylcholinesterase inhibitors or memantine from 2005 to 2009. A population study on community-dwelling older people in Italy

PURPOSE

The aims of this study are to analyse, in community-dwelling people aged 65+ living in Italy's Lombardy Region, electrocardiographic (ECG) monitoring for new users of the atypical antipsychotic quetiapine co-prescribed with acetylcholinesterase inhibitors (AChEIs) or memantine and to find independent predictors of ECG monitoring before and after the starting of this prescription.

METHODS

The Lombardy Region's administrative health database was used to retrieve prescriptions of ECG exams as well as prevalence rates of subjects aged 65+ who were prescribed such psychotropic drugs from 2005 to 2009. Multivariable analyses were adjusted for age, sex, number of drugs, treatment with beta-blockers, digoxin, verapamil or diltiazem, any antiarrhythmic drug and antidepressants.

RESULTS

Overall 2,623 community-dwelling older people started therapy with quetiapine, co-prescribed with AChEIs or memantine, during these 5 years. At least one ECG was performed in 714 cases (27.2 %) in the 6 months before-and in 398 cases (15.2 %) within 3 months after-the starting of this prescription. ECG monitoring was performed both before and after starting quetiapine in only 160 cases (6.1 %). At multivariable analyses, number of drugs taken, beta-blocker and antiarrhythmic drug use were found to be independent correlates of ECG monitoring whereas female sex was associated with a lower probability of receiving an ECG within 3 months after the initiation of quetiapine (odds ratio 0.78, 95 % CI 0.62-0.98).

CONCLUSIONS

ECG monitoring for new prescriptions of quetiapine in older people suffering from behavioural and psychological symptoms in dementia was actually performed infrequently, independently of the age of drug users, especially in women. Our results support the need for greater awareness within the medical community of the importance of such ECG monitoring.

Probable quetiapine-mediated prolongation of the QT interval

PURPOSE

QT prolongation can occur with both first- (FGA) and second-generation antipsychotics (SGA). QT prolongation was identified in an adult patient who presented to the emergency room with schizophrenia, fluid and electrolyte imbalances, and pneumonia. Quetiapine, an SGA, was a component of the pharmacotherapy regimen. Based on the Naranjo adverse drug reaction probability scale rating criteria, a probable causal association was made.

METHODS

PubMed and Ovid were searched using the terms antipsychotic, psychotropic, QT interval, corrected QT interval (QTc) prolongation, and quetiapine. References were examined for additional articles related to antipsychotic drugs and the QT interval.

DISCUSSION

In this patient, the use of quetiapine was identified as a contributing factor in QT prolongation. Prior QT prolongation was experienced with ziprasidone, another SGA. The antidepressant and dose remained consistent throughout the inpatient course of treatment. Other risk factors in this patient included hypokalemia, dehydration, pneumonia, age, gender, and concurrent usage of an antidepressant. Dual psychiatric diagnoses, preexisting cardiovascular disease, and electrolyte disturbances may increase this risk potential.

CONCLUSION

Psychiatric patients may be more at risk of cardiovascular complications, such as QT interval prolongation. The pharmacist can help evaluate risk factors and provide input into the care of all patients, particularly those identified as at risk.