Can Ativan (lorazepam) cause QT prolongation?

Ativan (Lorazepam) and QT Prolongation

Ativan (lorazepam) does not cause QT prolongation and is considered safe from a cardiac arrhythmia perspective. 1

Evidence Summary

• Benzodiazepines, including lorazepam, have not been associated with QT interval prolongation in clinical use 1
• Lorazepam is notably absent from comprehensive lists of QT-prolonging medications in major cardiology guidelines 1
• Unlike many psychotropic medications that carry arrhythmia risks, benzodiazepines are classified as "Class A" drugs - considered to be without any risk of QT prolongation or Torsades de Pointes 1

Comparison with Other Psychotropic Medications

Lorazepam's cardiac safety profile contrasts with many other psychotropic medications:

• Antipsychotics frequently cause QT prolongation, with varying degrees of risk:

  • High risk: Thioridazine (25-30ms prolongation) 1
  • Moderate risk: Haloperidol (7ms prolongation) 1
  • Low risk: Aripiprazole (0ms prolongation) 1

• Antidepressants can also affect cardiac conduction:

  • Tricyclic antidepressants (TCAs) prolong QT and increase risk of cardiac arrest (OR=1.69) 1
  • SSRIs like citalopram have prompted FDA warnings about QT prolongation 1

Clinical Implications

When sedation is needed in patients with risk factors for QT prolongation:

• Lorazepam is a preferred option over QT-prolonging alternatives like haloperidol 2
• In patients with cannabinoid hyperemesis syndrome at risk for QT prolongation, lorazepam is recommended as a safer alternative to haloperidol 2
• When combination therapy is needed, lorazepam can be safely co-administered with other medications 1

Risk Factors to Consider

While lorazepam itself doesn't prolong QT, be aware of other risk factors for QT prolongation when treating patients:

• Female gender 1
• Electrolyte abnormalities (especially hypokalemia, hypomagnesemia) 1
• Bradycardia or recent conversion from atrial fibrillation 1
• Heart failure or structural heart disease 1
• Concomitant use of QT-prolonging medications 1

Monitoring Recommendations

• ECG monitoring is not specifically required when administering lorazepam alone 1
• However, when lorazepam is combined with medications known to prolong QT (e.g., haloperidol), ECG monitoring may be warranted 3

Clinical Pearl

In patients requiring sedation who have risk factors for QT prolongation or a history of cardiac arrhythmias, lorazepam represents a safer choice compared to many alternatives, particularly antipsychotics 1, 2.