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Atrial Fibrillation Health Center

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Calcium Channel Blockers for Atrial Fibrillation


Generic Name Brand Name
diltiazem Cardizem, Taztia
verapamil Calan, Verelan

How It Works

These calcium channel blockers help slow the heart rate by blocking the number of electrical impulses that pass through the AV node into the lower heart chambers (ventricles).

Why It Is Used

Calcium channel blockers are rate-control medicines used for atrial fibrillation. They are used if your heart rate is too fast, which may cause symptoms.

How Well It Works

Rate-control medicines such as calcium channel blockers usually do not return your heart to a normal rhythm-in other words, your heartbeat will still be irregular. But these medicines can keep your heart from beating at a dangerously fast rate. This may also relieve symptoms caused by a fast heart rate.1

Your heart rate may not need to be very low. A heart rate of 110 beats per minute may be enough to help you.2

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Call 911 or other emergency services right away if you have:

Call your doctor if you have:

  • Hives.
  • Very slow heart rate (less than 50 beats per minute).
  • Skin rash.

Common side effects of this medicine include:

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Check your pulse. Your doctor may ask you to take your pulse regularly to make sure your heart rate is not too slow. To learn how to take your pulse, see the topic Taking a Pulse (Heart Rate) slideshow.gif. Your doctor might have you use a device to record your heart rate at home for a couple of days. This device is referred to by several names, including ambulatory electrocardiogram and Holter monitor.

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

If you are pregnant, breast-feeding, or trying to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments. And call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.


  1. Morady F, Zipes DP (2012). Atrial fibrillation: Clinical features, mechanisms, and management. In RO Bonow et al., eds., Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 9th ed., vol. 1, pp. 825-844. Philadelphia: Saunders.

  2. January CT, et al. (2014). 2014 AHA/ACC/HRS Guideline for the management of patients with atrial fibrillation: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. Circulation, published online March 28, 2014. DOI: 10.1161/CIR.0000000000000041. Accessed April 18, 2014.

ByHealthwise Staff
Primary Medical ReviewerRakesh K. Pai, MD, FACC - Cardiology, Electrophysiology
Specialist Medical ReviewerJohn M. Miller, MD, FACC - Cardiology, Electrophysiology

Current as ofAugust 5, 2014

WebMD Medical Reference from Healthwise

Last Updated: August 05, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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