What precautions should I take when starting Lexapro (escitalopram) with a history of bradycardia and a heart rate as low as 50 beats per minute?

Starting Lexapro with Pre-existing Bradycardia (Heart Rate 50 bpm)

You can start Lexapro with baseline bradycardia of 50 bpm, but you must obtain a baseline ECG before initiation and monitor your heart rate closely during the first 1-2 weeks of therapy, as escitalopram can cause further bradycardia in 0.5% of patients. 1

Key Safety Considerations

Baseline Assessment Required

• Obtain a 12-lead ECG before starting Lexapro to document your baseline heart rate, rhythm, and QTc interval 1, 2
• A heart rate of 50 bpm is considered minimally symptomatic bradycardia if you are not experiencing dizziness, syncope, chest pain, dyspnea, or fatigue 3, 4
• Asymptomatic bradycardia at 50 bpm does not require treatment or preclude starting Lexapro, but symptomatic bradycardia would require evaluation first 3, 2

Escitalopram-Specific Cardiac Effects

FDA labeling data shows escitalopram causes bradycardia in 0.5% of patients (compared to 0.2% with placebo), making it a documented but uncommon adverse effect 1. The mechanism appears distinct from QTc prolongation and involves sinus node effects 5, 6.

• Case reports document escitalopram-induced bradycardia occurring at therapeutic doses (20 mg), with heart rates dropping to as low as 39 bpm and causing presyncope 5
• One case showed 93.7% of heart beats below 60 bpm after 3 months of escitalopram therapy, which normalized after discontinuation 6
• The bradycardia typically develops within the first 3 months of therapy and resolves within 48 hours to 2 weeks after stopping the medication 5, 6

Monitoring Protocol

First Week of Therapy

• Check heart rate and blood pressure daily for the first 7 days, particularly if you are elderly or have any cardiac history 5
• Watch for symptoms of poor perfusion: altered mental status, dizziness, syncope, chest discomfort, or fatigue 7, 8
• If heart rate drops more than 30% from baseline, this signals high risk for severe bradycardia 9

Ongoing Monitoring

• Continue monitoring heart rate weekly for the first month 6
• Repeat ECG at 2-4 weeks after starting therapy to assess for any conduction changes 6, 2
• Any heart rate consistently below 40 bpm or symptomatic bradycardia requires immediate discontinuation 3, 5

Critical Drug Interactions to Avoid

Do not combine Lexapro with other medications that slow heart rate, as this dramatically increases bradycardia risk 6:

• Beta-blockers (atenolol, metoprolol, propranolol) - cause additive bradycardia 3, 8
• Calcium channel blockers (diltiazem, verapamil) - slow AV node conduction 3, 8
• Digoxin - one case showed severe bradycardia when combined with escitalopram 6
• Antipsychotics (quetiapine) - documented to worsen escitalopram-induced bradycardia 6

When to Stop Lexapro Immediately

Discontinue escitalopram and contact your physician if you develop 5, 6:

• Heart rate below 40 bpm at rest
• Dizziness, lightheadedness, or near-syncope episodes
• Chest pain or shortness of breath
• Documented heart rate drop of more than 30% from your baseline

The bradycardia will typically resolve within 48 hours of stopping the medication 5.

Starting Dose Recommendation

• Begin with 5 mg daily rather than the standard 10 mg dose to minimize cardiac effects 1
• The FDA data shows the 10 mg dose has similar adverse event rates to placebo (66% vs 61%), while 20 mg has significantly higher rates (86%) 1
• Only increase to 10 mg after 2 weeks if heart rate remains stable above 50 bpm 1, 2

Special Precautions

Your baseline heart rate of 50 bpm is not an absolute contraindication to Lexapro, as this rate can be physiologic and asymptomatic 3, 2. However, you are at higher risk for developing symptomatic bradycardia compared to patients with normal baseline heart rates 5, 6. The key is distinguishing whether your current bradycardia causes any symptoms - if you have no dizziness, fatigue, or exercise intolerance at 50 bpm, you can proceed with close monitoring 3, 4.