Treatment of QRS Widening Caused by SSRIs
The first-line treatment for QRS widening caused by SSRIs is administration of intravenous sodium bicarbonate (1-2 mEq/kg) until arterial pH reaches >7.45, followed by an infusion to maintain alkalosis. 1
Immediate Management
- Discontinue the SSRI or reduce the dose if QRS widening is detected 1
- Administer 1-2 mEq/kg IV boluses of sodium bicarbonate until arterial pH is >7.45, then provide an infusion of 150 mEq NaHCO3 per liter of D5W to maintain alkalosis 1
- In severe cases, increase pH to 7.50-7.55 1
- Consider hospitalization with continuous cardiac monitoring if the patient is symptomatic or has severe QT prolongation 2
- Check and correct electrolyte abnormalities, particularly hypokalemia and hypomagnesemia, which can worsen QRS widening and QT prolongation 2
Risk Assessment and Monitoring
- Monitor ECG regularly, especially in patients taking citalopram, which has been associated with the most significant QT prolongation among SSRIs (+12.8 ms) 3
- Pay special attention to elderly patients (>60 years) who are at higher risk 2
- Assess for concomitant use of other QT-prolonging medications, which increases risk 2
- Monitor renal function, as renal insufficiency leads to drug accumulation and predisposes to proarrhythmia 1
Alternative Treatment Options
- Consider switching to an SSRI with lower risk of QT prolongation, such as sertraline 4, 2
- Consider an SNRI (serotonin-norepinephrine reuptake inhibitor) as these have not shown significant association with cardiac arrest 2
- If an SSRI is still preferred, fluoxetine may have less effect on CYP450 isoenzymes compared to other SSRIs and potentially lower risk of drug interactions 2
- Avoid tricyclic antidepressants (TCAs) as they have been associated with QT prolongation and increased risk of cardiac arrest 2
Special Considerations
- For severe cases unresponsive to sodium bicarbonate, hypertonic saline solution (7.5% NaCl) has been shown to narrow QRS interval and improve hypotension within minutes 5
- Do not administer Class IA (quinidine, procainamide), Class IC (flecainide, propafenone), or Class III (amiodarone and sotalol) antiarrhythmics, which may exacerbate cardiac toxicity 1
- When transitioning to a new antidepressant, implement a gradual tapering plan to avoid discontinuation syndrome 6
- Start alternative antidepressants at a low dose and increase slowly while monitoring for symptoms 2
Monitoring During Treatment
- Perform serial ECGs to evaluate QRS duration and QT interval 1
- For patients on citalopram, maintain ECG monitoring even at the recommended maximum dose of 20 mg in patients over 60 years, as QT prolongation can still occur at this dose 3
- Monitor plasma potassium and magnesium levels regularly 1
- Consider exercise testing to detect QRS widening that occurs only at rapid heart rates (use-dependent conduction slowing) 1
Common Pitfalls to Avoid
- Do not abruptly discontinue SSRIs without a tapering plan 6
- Avoid combining SSRIs with other QT-prolonging medications, especially Class III antiarrhythmics like sotalol 4
- Do not mistake symptoms of SSRI discontinuation for physical illness or relapse into depression 6
- Remember that newer medications like diphenhydramine and bupropion are increasingly common causes of QRS complex prolongation in overdose settings 7