Does Coreg (carvedilol) slow the heart rate?

Carvedilol Does Slow Heart Rate

Yes, carvedilol (Coreg) does slow the heart rate through its beta-blocking properties. 1 Carvedilol is a non-selective beta-blocker that blocks both beta-1 and beta-2 adrenergic receptors, with beta-1 blockade being primarily responsible for reducing heart rate.

Mechanism of Action

Carvedilol has a unique pharmacological profile that contributes to its heart rate-lowering effects:

• It is a racemic mixture where the S(-) enantiomer provides non-selective beta-adrenoreceptor blocking activity 1
• It blocks beta-1 receptors in the heart, which decreases heart rate, contractility, and cardiac output 2
• It has no intrinsic sympathomimetic activity, meaning it doesn't partially activate receptors 1
• It also has alpha-1 blocking properties, providing vasodilatory effects 1

Evidence for Heart Rate Reduction

Multiple guidelines and studies confirm carvedilol's heart rate-lowering effects:

• The 2011 ACCF/AHA/HRS guidelines note that carvedilol lowers ventricular rate both at rest and during exercise in patients with atrial fibrillation 3
• In a study of patients with chronic atrial fibrillation, carvedilol reduced mean heart rate from 101.9 ± 13.9 to 85.2 ± 15.2 bpm (13.9% reduction) 4
• The same study showed total heart beats were significantly decreased from 128 to 115 × 1,000/day (10.7% reduction) 4

Clinical Applications

Carvedilol's heart rate-lowering effect is utilized in several clinical scenarios:

1. Atrial Fibrillation: Guidelines recommend beta-blockers including carvedilol for rate control in atrial fibrillation 3

2. Multifocal Atrial Tachycardia (MAT): Beta-blockers can be used with caution to treat MAT in the absence of respiratory decompensation, sinus node dysfunction, or AV block 3

3. Heart Failure: Carvedilol is one of three beta-blockers (along with bisoprolol and metoprolol succinate) shown to reduce mortality in heart failure patients 3

Comparative Effects

When compared to other medications:

• Beta-blockers (including carvedilol) were the most effective drug class for rate control in the AFFIRM study, achieving heart rate endpoints in 70% of patients compared with 54% with calcium channel blockers 3
• Carvedilol provides better control of exercise-induced tachycardia than digoxin 3

Precautions and Monitoring

When using carvedilol for its heart rate-lowering effects, be aware of:

• Risk of bradycardia, especially when combined with other drugs that slow heart rate (like digoxin or amiodarone) 1
• Potential for heart block, particularly in patients with pre-existing conduction abnormalities 3
• Need to monitor heart rate and blood pressure after each dose titration 2
• Contraindications in patients with severe bradycardia, second or third-degree AV block without a pacemaker, cardiogenic shock, or decompensated heart failure 1

Dosing Considerations

• Start with low doses (e.g., 3.125 mg twice daily) and titrate gradually to avoid symptomatic bradycardia 2
• Target dose is typically 12.5-25 mg twice daily, depending on the indication 2
• When converting from metoprolol succinate 50 mg daily to carvedilol, the equivalent dose is 12.5 mg twice daily 2

In summary, carvedilol effectively reduces heart rate through its beta-blocking properties, making it useful in various cardiovascular conditions where heart rate control is desired.