Can escitalopram (selective serotonin reuptake inhibitor) cause bradycardia (abnormally slow heart rate)?

Can Escitalopram Cause Bradycardia?

Yes, escitalopram can cause bradycardia, though this is an uncommon adverse effect that occurs in approximately 0.5% of patients at therapeutic doses. 1

Evidence from FDA Drug Labeling

The FDA-approved prescribing information for escitalopram documents bradycardia as a measurable adverse effect:

• In controlled trials, 0.5% of escitalopram-treated patients developed bradycardic outliers (heart rate <50 bpm with ≥25% decrease from baseline), compared to 0.2% with placebo 1
• ECG monitoring in 625 escitalopram patients versus 527 placebo patients revealed this small but statistically significant difference 1

Clinical Evidence from Case Reports and Research

Bradycardia with escitalopram is well-documented in both therapeutic dosing and overdose scenarios:

Therapeutic Dose Bradycardia

• A case report documented severe sinus bradycardia (93.7% of heart rate readings <60 bpm) in an 82-year-old woman taking escitalopram at standard doses, which resolved within 2 weeks of discontinuation and recurred upon rechallenge 2
• Another case described symptomatic bradycardia (heart rate 39 bpm) with presyncope in a patient taking citalopram 20 mg daily, which resolved within 48 hours of drug cessation 3
• The Naranjo Algorithm score indicated escitalopram as a highly probable cause in documented cases 2

Overdose-Related Bradycardia

• In a study of 79 escitalopram overdoses, bradycardia (pulse <60 bpm) occurred in 14% of cases, often associated with QT prolongation 4
• Bradycardia in overdose was frequently accompanied by normal or slow pulse rates and abnormal QT-HR pairs 4
• One overdose case showed persistent sinus bradycardia for over 71 hours post-ingestion 5

Mechanism and Risk Context

The primary cardiac concern with escitalopram is QT prolongation rather than bradycardia, but both can occur:

• European Heart Journal guidelines classify escitalopram as having propensity for QT prolongation, with FDA and EMA imposing maximum dose restrictions (particularly for patients >60 years) 6
• SSRIs as a class increased risk of cardiac arrest (OR 1.21) in a Danish nationwide registry study 6
• Important medications that can interact with escitalopram to prolong QT include domperidone, ondansetron, palosetron, granisetron, prochlorperazine, olanzapine, venlafaxine, sertraline, and mirtazapine 6

Clinical Management Algorithm

When Bradycardia Occurs on Escitalopram:

1. Immediate assessment: Obtain 12-lead ECG to evaluate for conduction abnormalities and measure QTc interval 7

2. Check for contributing factors:

   • Concomitant medications causing bradycardia (beta-blockers, nondihydropyridine calcium channel blockers, digoxin, amiodarone) 8
   • Electrolyte abnormalities (hypokalemia, hypomagnesemia) 6
   • Baseline cardiac disease 9

3. Symptomatic bradycardia management:

   • Discontinue escitalopram immediately if iatrogenic cause cannot be ruled out 2
   • For acute symptomatic bradycardia with hemodynamic compromise, administer atropine 0.5 mg IV every 3-5 minutes up to 3 mg total 6, 7
   • Monitor continuously for 24-48 hours after medication adjustment 7

4. ECG monitoring duration:

   • In overdose cases, ECG monitoring should continue for at least 2 days (48-71 hours) to prevent life-threatening arrhythmias 5
   • Serial ECGs should assess both heart rate and QTc interval 5

Critical Pitfalls to Avoid

• Never combine escitalopram with other QT-prolonging medications without careful monitoring, as this creates additive cardiac risk 9
• Do not use escitalopram in patients with congenital long QT syndrome, pre-existing bradycardia, or significant electrolyte abnormalities 9
• Avoid assuming bradycardia is benign—it may herald more serious conduction abnormalities, particularly in elderly patients or those with cardiac comorbidities 2, 3
• In patients with cardiovascular disease using sinoatrial node inhibitors (digoxin, beta-blockers), escitalopram requires heightened vigilance 2

Comparison with Other SSRIs

Among SSRIs, citalopram and escitalopram carry the highest cardiac risk:

• Paroxetine has the lowest risk of QTc prolongation and should be preferred in high-risk cardiac patients 9
• Sertraline and fluoxetine represent intermediate-risk alternatives 9
• The European Heart Journal recommends avoiding citalopram/escitalopram in patients with moderate to high cardiac risk 9

Large-Scale Safety Data

A comprehensive analysis of 3,298 escitalopram-treated patients in controlled trials showed:

• Small but statistically significant 2 beats per minute decrease in heart rate compared to placebo 10
• Cardiac-associated adverse events occurred in 1.9% of escitalopram patients versus 2.2% of placebo patients in short-term studies 10
• The effect on heart rate was consistent across acute (8-12 weeks) and long-term (24 weeks) treatment 10