Can citalopram (Selective Serotonin Reuptake Inhibitor (SSRI)) cause bradycardia with pauses?

Citalopram and Bradycardia with Pauses

Yes, citalopram can cause bradycardia with pauses, particularly at higher doses or in susceptible individuals, and should be used with caution in patients with pre-existing cardiac conditions.

Mechanism and Evidence

Citalopram has been associated with cardiac effects through several mechanisms:

• Inhibition of hERG potassium channels leading to delayed cardiac repolarization 1
• Dose-dependent QTc prolongation that can create substrate for arrhythmias 2
• Direct effects on cardiac conduction that can manifest as bradycardia 3, 4

The FDA drug label specifically mentions bradycardia as an infrequent adverse effect (0.1-1%) of citalopram treatment 2. Multiple case reports have documented bradycardia occurring with therapeutic doses of citalopram:

• A 60-year-old woman developed symptomatic bradycardia (39 beats/min) and hypotension after just two weeks on citalopram 20 mg/day 3
• A 47-year-old woman presented with marked sinus bradycardia (34 beats/min) after increasing from 20 mg to 40 mg daily 4
• In overdose situations, severe and prolonged bradycardia with pauses requiring temporary pacemaker insertion has been reported 5

Risk Factors

Several factors increase the risk of citalopram-induced bradycardia:

• Older age (>60 years)
• Pre-existing cardiac conditions
• Concomitant use of other medications that affect heart rate:
  • Beta-blockers
  • Calcium channel blockers
  • Other QT-prolonging medications 6
• Higher doses of citalopram (>40 mg/day, or >20 mg/day in elderly) 2
• Electrolyte abnormalities (hypokalemia, hypomagnesemia)

Monitoring and Management

For patients on citalopram:

1. Baseline assessment:

   • ECG before starting treatment, especially in high-risk patients
   • Electrolyte panel (potassium, magnesium)
   • Review of concurrent medications

2. During treatment:

   • Monitor heart rate and blood pressure in the first week and when doses are modified 3
   • Follow-up ECG monitoring for high-risk patients
   • Consider dose reduction if bradycardia develops
   • Discontinue if significant bradycardia (HR <50) or pauses occur

3. If bradycardia with pauses develops:

   • Discontinue citalopram
   • Monitor cardiac parameters until normalization
   • Consider temporary pacing for severe cases 5

Alternative Antidepressants

For patients with cardiac risk factors or those who develop bradycardia on citalopram:

• Sertraline has a more favorable cardiovascular safety profile 1
• Mirtazapine has been shown to be safe in cardiac patients 1
• Avoid tricyclic antidepressants which have different but significant cardiac effects

Important Considerations

• The European Heart Journal classifies citalopram as a Class B drug with propensity for QT prolongation 6
• The maximum recommended dose is 40 mg/day (20 mg/day in patients >60 years) due to dose-dependent cardiac effects 2
• Bradycardia may occur independently of QT prolongation 3
• Resolution typically occurs within 24-48 hours after discontinuation in therapeutic dose cases 3, 4

Careful patient selection, appropriate dosing, and monitoring are essential when prescribing citalopram to minimize the risk of bradycardia with pauses and other cardiac complications.