Assessing QT Interval Prolongation and its Associated Risks with Antipsychotics
ABSTRACT Several antipsychotics are associated with the ventricular tachycardia torsade de pointes (TdP), which may lead to sudden cardiac death (SCD), because of their inhibition of the cardiac delayed potassium rectifier channel. This inhibition extends the repolarization process of the ventricles of the heart, illustrated as a prolongation of the QT interval on a surface ECG. SCD in individuals receiving antipsychotics has an incidence of approximately 15 cases per 10,000 years of drug exposure but the exact association with TdP remains unknown because the diagnosis of TdP is uncertain. Most patients manifesting antipsychotic-associated TdP and subsequently SCD have well established risk factors for SCD, i.e. older age, female gender, hypokalaemia and cardiovascular disease. QT interval prolongation is the most widely used surrogate marker for assessing the risk of TdP but it is considered somewhat imprecise, partly because QT interval changes are subject to measurement error. In particular, drug-induced T-wave changes (e.g. flattening of the T-wave) may complicate the measurement of the QT interval. Furthermore, the QT interval depends on the heart rate and a corrected QT (QTc) interval is often used to compensate for this. Several correction formulas have been suggested, with Bazett's formula the most widely used. However, Bazett's formula overcorrects at a heart rate above 80 beats per minute and, therefore, Fridericia's formula is considered more appropriate to use in these cases. Several other surrogate markers for TdP have been developed but none of them is clinically implemented yet and QT interval prolongation is still considered the most valid surrogate marker. Although automated QT interval determination may offer some assistance, QT interval determination is best performed by a cardiologist skilled in its measurement. A QT interval >500 ms markedly increases the risk for TdP and SCD, and should lead to discontinuation of the offending drug and, if present, correction of underlying electrolyte disturbances, particularly serum potassium and magnesium derangements. Before prescribing antipsychotics that may increase the QTc interval, the clinician should ask about family and personal history of SCD, presyncope, syncope and cardiac arrhythmias, and recommend cardiology consultation if history is positive.
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ABSTRACT: Abstract Objectives. This article presents an overview of the current literature on biological markers for alcoholism, including markers associated with the pharmacological effects of alcohol and markers related to the clinical course and treatment of alcohol-related problems. Many of these studies are well known, while other studies cited are new and still being evaluated. Methods. In this paper we first describe known biomarkers of alcohol-related disorders, review their features and the problems involved in their use. We then consider future developments on biomarkers and their possible impact on the field. Results. More recent findings cited include the work on type 7 adenylcyclase (AC) polymorphism and its lower expression levels in female alcoholics. Neuroimaging studies involving biomarkers have also reported brain volume reductions of gray and white matter, including amygdala and subcortical regions in alcoholic patients, while a high association between the copy number variations (CNVs) in 6q14.1/5q13.2 and alcohol dependence has more recently been identified in genetic studies. Conclusions. In addition to their possible importance for diagnosis, biomarkers may have utility for predicting prognosis, progression of the disorder, the development of new treatments, and monitoring treatment effects. Although such findings should be verified in independent studies, the search for new biomarkers is continuing. Several potential candidate biomarkers have been found recently in blood, imaging, and genetic studies with encouraging results.The World Journal of Biological Psychiatry 12/2013; 14(8):549-64. DOI:10.3109/15622975.2013.838302 · 4.23 Impact Factor
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ABSTRACT: 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.Therapeutic Advances in Psychopharmacology 03/2015; 5(1):26-31. DOI:10.1177/2045125314560738 · 1.53 Impact Factor
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ABSTRACT: The goals and strategies of treatment in schizophrenia may vary according to the phase and severity of the illness. Antipsychotics remain the cornerstone in the acute phase treatment, in the long-term maintenance therapy and in the prevention of relapse of schizophrenia. This paper is intended to review the current practice in the management of the acute treatment of schizophrenia based on the recently published guidelines from the World Federation of Societies of Biological Psychiatry (WFSBP). Both first generation antipsychotics (FGAs) and second generation antipsychotics (SGAs) are effective in the acute treatment of schizophrenia and in relapse prevention. Clinicians must keep in mind that most patients are likely to require long-term, if not life-long, treatment which determines treatment strategy with an optimal balance between efficacy, side effects and compliance. In this regards, SGAs do have some advantages, but the risk of metabolic syndrome must be taken into account and carefully checked at regular intervals during the follow-up.Psychiatria Danubina 03/2014; 26(1):2-11. · 0.65 Impact Factor