Can Amlodipine (calcium channel blocker) worsen bradycardia (abnormally slow heart rate)?

From the Guidelines

Amlodipine is unlikely to worsen bradycardia in most individuals, but it can still influence heart rate in patients with pre-existing conduction abnormalities or bradycardia. Amlodipine is a dihydropyridine calcium channel blocker that primarily affects blood vessels, causing vasodilation and lowering blood pressure. While it has less direct effect on the heart compared to non-dihydropyridine calcium channel blockers (like verapamil or diltiazem), it can still influence heart rate, particularly in patients with pre-existing conduction abnormalities or bradycardia.

Key Points to Consider

• The mechanism involves amlodipine's ability to reduce calcium influx into cardiac cells, which can suppress the sinoatrial node's activity and slow atrioventricular conduction 1.
• Patients with existing bradycardia, sick sinus syndrome, or those taking other medications that slow heart rate (such as beta-blockers or digoxin) should be monitored closely when starting or adjusting amlodipine therapy.
• Typical symptoms of worsening bradycardia include dizziness, fatigue, weakness, confusion, or syncope.
• If these symptoms develop while taking amlodipine, patients should contact their healthcare provider promptly for evaluation, as dosage adjustment or medication changes may be necessary.

Evidence-Based Recommendation

According to the 2012 ACCF/AHA focused update incorporated into the ACCF/AHA 2007 guidelines for the management of patients with unstable angina/non-st-elevation myocardial infarction, amlodipine has a long duration of action and its side effects include headache and edema, but it does not typically cause bradycardia 1. However, it is essential to consider the individual patient's condition and monitor them closely for any potential adverse effects.

Clinical Implications

In clinical practice, amlodipine can be a valuable treatment option for patients with hypertension or angina, but it is crucial to weigh the benefits against the potential risks, particularly in patients with pre-existing heart conditions. By carefully evaluating the patient's medical history and monitoring them closely, healthcare providers can minimize the risk of adverse effects and optimize the treatment outcome.

From the FDA Drug Label

Although the acute intravenous administration of amlodipine decreases arterial blood pressure and increases heart rate in hemodynamic studies of patients with chronic stable angina, chronic oral administration of amlodipine in clinical trials did not lead to clinically significant changes in heart rate or blood pressures in normotensive patients with angina Electrophysiologic Effects: Amlodipine does not change sinoatrial nodal function or atrioventricular conduction in intact animals or man.

Amlodipine's effect on heart rate is not significant in most cases, as it does not change sinoatrial nodal function or atrioventricular conduction.

• Key points:
  • Amlodipine does not significantly alter heart rate in clinical trials.
  • It does not change sinoatrial nodal function or atrioventricular conduction. Therefore, Amlodipine is unlikely to worsen bradycardia in most patients, as it does not have a significant negative effect on heart rate 2 2.

From the Research

Amlodipine and Bradycardia

• Amlodipine is a calcium channel blocker that predominantly affects vascular smooth muscle cells, typically causing vasodilatory effects and reflex tachycardia rather than bradycardia 3.
• However, in cases of amlodipine overdose, bradycardia can occur, as seen in a case where an 81-year-old woman presented with refractory bradycardia after ingesting a large amount of amlodipine tablets 3.
• Another case report described a patient who developed severe bradycardia and hypotension after consuming a combination of amlodipine and atenolol, highlighting the potential for worsening cardiovascular depression when these drugs are taken together 4.
• A study on cardiac rhythm disturbances associated with amlodipine acute intoxication found that the drug can cause bradyarrhythmias, such as low atrial rhythm and atrioventricular block, suggesting that amlodipine can depress cardiac automatism and conduction in severe intoxication cases 5.
• In contrast, a long-term study on the haemodynamic effects of amlodipine in patients with essential hypertension found no significant changes in heart rate, suggesting that amlodipine does not typically worsen bradycardia in therapeutic doses 6.

Key Findings

• Amlodipine overdose can cause bradycardia, particularly when combined with other medications like atenolol 3, 4.
• Severe amlodipine intoxication can lead to cardiac rhythm disturbances, including bradyarrhythmias 5.
• Therapeutic doses of amlodipine do not typically cause significant changes in heart rate or worsen bradycardia 6.