What medications can be used to lower heart rate (hr) in patients with tachycardia?

Medications for Lowering Heart Rate in Tachycardia

Beta blockers are the first-line medications for lowering heart rate in patients with tachycardia, with metoprolol being particularly effective for rate control in various tachyarrhythmias. 1

First-Line Medications

Beta Blockers

• Most effective drug class for rate control, achieving heart rate endpoints in 70% of patients compared to 54% with calcium channel blockers 1
• Reduce heart rate by blocking catecholamine effects, reducing AV node conduction 1
• Options include:
  • Metoprolol: 25-100 mg BID (immediate release) or 50-400 mg daily (extended release) 1
  • Atenolol: 25-100 mg daily 1
  • Esmolol: For IV administration in acute settings (500 mcg/kg IV bolus, then 50-300 mcg/kg/min) 1
  • Propranolol: 80-240 mg daily in divided doses 1
• Contraindications: Asthma, obstructive airway disease, decompensated heart failure, pre-excited atrial fibrillation/flutter 1

Non-dihydropyridine Calcium Channel Blockers

• Commonly used for tachycardia treatment with improved quality of life and exercise tolerance 1
• Slow AV node conduction and increase AV node refractoriness 1
• Options include:
  • Diltiazem: Initial dose 15-20 mg IV over 2 minutes; maintenance 120-360 mg daily orally 1
  • Verapamil: Initial dose 2.5-5 mg IV over 2 minutes; maintenance 120-360 mg daily orally 1
• Contraindicated in decompensated heart failure, pre-excited AF/flutter, or rhythms consistent with VT 1

Second-Line Medications

Digoxin

• Useful for rate control in patients with heart failure or LV dysfunction 1
• Dosing: 0.125-0.375 mg daily orally 1
• Limitations:
  • Delayed onset of action (60+ minutes) with peak effect up to 6 hours 1
  • Less effective during high sympathetic tone states 1
  • Not effective for exercise-induced tachycardia 1

Amiodarone

• Consider when other measures are unsuccessful or contraindicated 1
• Multichannel blocker with additional beta-blocking properties 1
• Dosing: 150 mg IV over 10 minutes, followed by 1 mg/min infusion for 6 hours, then 0.5 mg/min 1
• Oral dosing: 800 mg daily for 1 week, 600 mg daily for 1 week, 400 mg daily for 4-6 weeks, then 200 mg daily maintenance 1
• Side effects include bradycardia, hypotension, pulmonary toxicity, thyroid dysfunction 1

Ivabradine

• Novel agent that selectively inhibits the I(f) current in the sinoatrial node 2
• Particularly useful for inappropriate sinus tachycardia 1
• Dosing: 2.5-7.5 mg twice daily 1
• Can be combined with beta blockers for enhanced rate control 1
• Side effects include phosphenes (visual brightness) in about 3% of patients 1

Special Considerations

• For acute rate control in unstable patients, IV medications or electrical cardioversion may be required 1
• In pre-excited atrial fibrillation, avoid digoxin, non-dihydropyridine calcium channel blockers, and amiodarone as they may increase ventricular response 1
• For specific tachyarrhythmias:
  • Atrial fibrillation/flutter: Beta blockers or calcium channel blockers are first-line 1
  • SVT: Adenosine (6 mg IV rapid push, may repeat with 12 mg) for acute termination 1
  • Inappropriate sinus tachycardia: Beta blockers or ivabradine 1

Monitoring and Titration

• Assess heart rate control both at rest and during activity 1
• Beta blockers should be titrated to the highest tolerated dose regardless of baseline heart rate 3
• Target heart rate reduction rather than specific medication dose 4
• Monitor for side effects such as hypotension, bradycardia, and heart failure exacerbation 1

Common Pitfalls

• Underdosing of beta blockers is common in clinical practice - most patients receive less than half the recommended target dose 5
• Limited up-titration occurs in the first 60-90 days after hospital discharge 5
• Combination therapy may be needed for refractory tachycardia, but monitor closely for excessive bradycardia 1
• Avoid non-dihydropyridine calcium channel blockers in patients with decompensated heart failure 1