Benzodiazepines and QT Prolongation
Benzodiazepines do not cause QT interval prolongation and are considered safe from a cardiac arrhythmia perspective, even with long-term use at high dosages. 1
Classification and Safety Profile
Benzodiazepines are classified as "Class A" drugs by the European Heart Journal, meaning they are considered to be without any risk of QT prolongation or Torsades de Pointes (TdP). 1
While in vitro studies have shown both inhibition and activation of potassium currents during benzodiazepine exposure, no changes in QT duration have been reported in clinical use. 1
A 2024 study of 251 Italian inpatients with benzodiazepine dependence found no significant relationship between QTc prolongation and benzodiazepine use, even with long-term use at high dosages, concluding that benzodiazepines can be considered safe in terms of cardiovascular complications. 2
Clinical Implications
The European Society of Cardiology recommends lorazepam as a safe option for patients at risk of QT prolongation, as it does not cause QT prolongation and is considered safe from a cardiac arrhythmia perspective. 3
Benzodiazepines are notably absent from comprehensive lists of QT-prolonging medications in major cardiology guidelines from the European Heart Journal and other authoritative sources. 3
A 2010 study of 1,017 patients with schizophrenia confirmed that benzodiazepines did not prolong the QTc interval, in contrast to many first-generation antipsychotics. 4
Monitoring Recommendations
ECG monitoring is not specifically required when administering benzodiazepines alone for QT prolongation concerns. 3
When benzodiazepines are combined with medications known to prolong QT (such as haloperidol, methadone, or certain antidepressants), monitoring should be based on the risk profile of the co-administered QT-prolonging agent, not the benzodiazepine. 1
Contrast with Other Psychotropic Medications
Unlike benzodiazepines, many other psychotropic medications carry significant QT prolongation risk:
Antipsychotics: Thioridazine (25-30ms prolongation), haloperidol (7ms), quetiapine (6ms), and ziprasidone (5-22ms) all prolong QT interval. 3, 5
Antidepressants: Tricyclic antidepressants increase cardiac arrest risk (OR=1.69), and SSRIs like citalopram have prompted FDA warnings about QT prolongation. 1, 3
Methadone: Causes pronounced QT prolongation with documented cases of TdP. 1
Common Pitfalls to Avoid
Do not withhold benzodiazepines due to QT prolongation concerns in patients who require anxiolytic therapy, as they carry no such risk. 1, 3
Do not confuse benzodiazepines with other psychotropic medications that do carry QT prolongation risk when making prescribing decisions for patients with cardiac risk factors. 1
When managing agitation in patients at risk for QT prolongation, benzodiazepines represent a safer alternative to antipsychotics from a cardiac standpoint. 3