Does Atenolol Prolong QT Interval?
Atenolol does not typically prolong the QT interval and may actually shorten it in some patients. 1
Evidence on Atenolol and QT Interval
Guideline Recommendations and Clinical Evidence
- According to the 2017 AHA/ACC/HRS guideline for management of ventricular arrhythmias, atenolol is specifically mentioned as one of the beta-blockers that has been shown to be effective for risk reduction in Long QT Syndrome (LQTS) 1
- Unlike medications such as sotalol, dofetilide, and amiodarone which are known to prolong QT interval, atenolol is not listed among QT-prolonging medications in clinical guidelines 1
- A comparative study demonstrated that atenolol actually induced a significant and constant reduction in QTc interval, in contrast to other beta-blockers like acebutolol which prolonged QTc 2
Mechanism and Clinical Implications
- Beta-blockers like atenolol work primarily through beta-adrenergic blockade rather than through ion channel effects that typically cause QT prolongation 1
- In a study investigating the effects of autonomic activation on QTc interval, atenolol did not prolong QTc and actually attenuated QTc changes during exercise 3
- A 10-year experience study using atenolol in children with genetically proven LQTS found it to be effective and well-tolerated, with only one patient developing ventricular arrhythmia while on treatment 4
Comparison with Other Beta-Blockers
- Unlike sotalol, which has both beta-blocking and Class III antiarrhythmic properties that prolong QT interval, atenolol does not have significant Class III effects 5
- A direct comparison between sotalol and atenolol showed that sotalol caused significant lengthening of QT interval (average increase of 43 ms or 9%) compared to atenolol 5
Clinical Applications and Monitoring
Use in LQTS Patients
- Atenolol is recommended as one of the beta-blockers for treatment of LQTS, particularly for LQTS type 1 1
- In LQTS patients, atenolol has been shown to reduce the risk of cardiac events, with effectiveness reported at a mean dose of 1.58 ± 0.51 mg/kg/day in pediatric populations 4
Important Considerations
When prescribing any medication to patients at risk for QT prolongation, clinicians should:
- Obtain baseline ECG before starting treatment
- Monitor electrolytes, particularly potassium and magnesium
- Avoid concurrent use of other QT-prolonging medications 6
While atenolol itself doesn't typically prolong QT, caution should be exercised when combining it with medications known to prolong QT interval or cause electrolyte disturbances (e.g., indapamide has been reported to cause QT prolongation in a patient on atenolol) 7
Conclusion
Unlike some other beta-blockers such as sotalol, atenolol does not prolong the QT interval and may actually shorten it. This makes it a suitable choice for patients who require beta-blockade but are at risk for QT prolongation or torsades de pointes. Atenolol is specifically recommended in guidelines for management of patients with Long QT Syndrome, further supporting its cardiac safety profile regarding QT interval effects.