Medications That Can Induce Bradycardia
Beta-blockers, calcium channel blockers (particularly verapamil and diltiazem), and digoxin are the primary medications that can induce bradycardia, often through their negative chronotropic effects on the heart. 1, 2
Common Medications That Cause Bradycardia
Cardiovascular Medications
- Beta-blockers (propranolol, metoprolol, carvedilol) - These medications block beta-adrenergic receptors, reducing heart rate and are a major cause of drug-induced bradycardia 3, 4
- Non-dihydropyridine calcium channel blockers (verapamil, diltiazem) - These agents slow AV nodal conduction and decrease heart rate 5
- Digoxin - Can cause bradyarrhythmias at therapeutic doses in sensitive individuals or in overdose 2
- Antiarrhythmic drugs (amiodarone, sotalol, propafenone) - Many have negative chronotropic properties 1, 2
- Ivabradine - Concurrent use with other negative chronotropic agents like diltiazem can exacerbate bradycardia 5
- Clonidine - Can cause marked sinus bradycardia 1
Chemotherapeutic Agents
- Cisplatin, 5-fluorouracil, paclitaxel/docetaxel - These agents have been associated with bradycardia 1, 2
- Thalidomide and arsenic trioxide - Can induce bradycardia through various mechanisms 2
Other Medications
- Opioids - Can induce bradycardia through parasympathetic stimulation 6
- Cholinergic agents - Increase vagal tone, slowing heart rate 2
- Lithium - Can cause bradyarrhythmias, especially at toxic levels 1
- Methyldopa - Listed as a cause of bradycardia 1
- Risperidone - Can induce bradycardia in some patients 1
- Interferon - Associated with bradycardia 1
Risk Factors for Drug-Induced Bradycardia
- Advanced age - Elderly patients are more susceptible to drug-induced bradycardia 7, 8
- Renal or hepatic impairment - Affects drug metabolism and clearance 3, 8
- Polypharmacy - Especially combinations of negative chronotropic agents 8
- Pre-existing cardiac disease - Increases susceptibility to bradycardia 6
- Electrolyte abnormalities - Hypokalemia or hypocalcemia can potentiate bradycardia 2
Dangerous Drug Combinations
- Beta-blockers + calcium channel blockers - This combination can have synergistic effects on heart rate, causing profound bradycardia 3, 5, 8
- Beta-blockers + digoxin - Both slow AV conduction and decrease heart rate, increasing risk of bradycardia 3, 4
- Sodium channel blockers + beta-blockers - Can cause severe bradycardia, even months after starting therapy 7
- Multiple negative chronotropic agents - The risk increases with each additional agent 8
Clinical Significance and Management
- Symptoms of clinically significant bradycardia include syncope, dizziness, fatigue, chest pain, and dyspnea 9, 10
- Acute management of symptomatic bradycardia may include atropine, especially for vagally-mediated bradycardia 1, 9
- For medication-induced bradycardia, discontinuation of the offending agent is the primary intervention 9, 11
- In severe cases, temporary pacing may be required until the medication effect resolves 9
- Prevention strategies include careful medication selection, dose adjustment, and monitoring in high-risk patients 11
Important Caveats
- Some patients may develop bradycardia even months after starting a medication, particularly with combinations of negative chronotropic agents 7
- Bradycardia can occur at therapeutic doses in sensitive individuals 2, 8
- Athletes and young, healthy individuals often have physiologic bradycardia that is not pathological 9, 10
- Always consider drug-induced causes when evaluating a patient with new-onset bradycardia 11