All medications have potential side effects and risks. Antiarrhythmic drugs must be taken daily and indefinitely as a treatment for Afib. There are also side effects that can be hard to manage. These side effects may include proarrhythmia. Proarrhythmia means that the drug has caused your arrhythmia to worsen or caused you to develop a new arrhythmia that is as bad or worse than the original problem.1

When medication proves unsuccessful, the American College of Cardiology (ACC), the American Heart Association (AHA) and the Heart Rhythm Society (HRS) suggest catheter (cardiac) ablation or surgical ablation as a safe and effective treatment option for some arrhythmias.2

Rate control heart medications

As mentioned in the treatment overview section, rate control medications are used to slow your heart rate. Two common types of rate control medications are beta blockers and calcium channel blockers.

Beta Blockers:

Beta-blockers slow your heart rate, relax your blood vessels and make it easier for your heart to pump blood. Common side effects of these drugs include dizziness, weakness, fatigue, cold hands and feet, dry mouth, dry eyes, headache, nausea, diarrhea, or constipation.3

Calcium Channel Blockers:

Calcium channel blockers are also called "calcium antagonists." These medicines work by interrupting the movement of calcium into your heart and blood vessel tissues to slow your heart rate.4 Potential side effects of these drugs include lightheadedness, low blood pressure, decreased heart rate, drowsiness, constipation, swelling in the feet, ankles, and legs, increased appetite, and acid reflux.5

Rhythm control heart medications

As the name implies, rhythm control medication may be used to try to restore your heart's normal rhythm. Two notable rhythm control medications are sodium channel blockers and anticoagulants

Sodium Channel Blockers:

Sodium channel blockers slow the electrical conductivity of your heart to improve rhythm problems. These drugs can cause gastrointestinal side effects such as nausea, abdominal pain and diarrhea. Some patients develop allergic reactions with symptoms such as rash, fever, anemia, low blood platelet counts and hepatitis. Central nervous system side effects may include tinnitus, delirium, and impaired hearing and vision. The most dangerous side effect of these antiarrhythmic drugs is that they can cause a form of arrhythmia called ventricular tachycardia, whereby the ventricles contract too rapidly.6


Anticoagulants are often prescribed to help reduce your stroke risk if you have atrial fibrillation. These drugs, also commonly known as blood thinners, are helpful for preventing blood clots from forming inside your heart. However, they also can prevent your blood from clotting at times when you need it to clot. As a result, a minor cut or skin abrasion can become a complicated and inconvenient, taking far longer to clot or requiring extra care. Nosebleeds are also a common occurrence for people who take blood thinners.7 These minor types of bleeding will require you to take extra precautions with your daily activities such as wearing extra protective gear, paying closer attention while doing simple hygiene tasks like brushing your teeth or trimming your nails. You may even find it necessary to give up some of the hobbies or activities you enjoy because they pose an increased risk for injuries.

Blood thinners can also have very serious and life-threatening side effects. These medications can make you more susceptible to internal bleeding, such as if you sustain a serious fall or accident, and to conditions such as stomach ulcers.

AFib Medication Efficacy and Outcomes

Regarding the effectiveness of rate control medications, it is important to keep in mind that these drugs don’t work at all for some patients, for some their effectiveness can diminish with long-term use, and for others the drugs are effective but the side effects they experience outweigh the usefulness of the drug.8 A large-scale study found that beta blockers have the best outcomes in terms of extending lifespan, followed next by calcium channel blockers and then digoxin, which is associated with the highest risk of mortality among all forms of rate control medications.9 However, when medication, as an overall approach, is compared to catheter ablation it has been found that medication is less effective in terms of extending lifespan and preventing emergency hospitalizations. In a study that compared the two treatment methods, catheter ablation was twice as effective as medication at preventing deaths due to cardiovascular causes.10

Learn more about catheter ablation as a treatment option for AFib.

1Heart Rhythm Society. "Treatments." Copyright, 2004.
2January CT, Wann LS, Alpert JS, et al. 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation: Executive Summary, Journal of the American College of Cardiology (2014), doi: 10.1016/j.jacc.2014.03.021.
3Marks L Beta Blockers – Side Effects and Precautions. What are Beta-Blockers? Everyday Health. Beta Blockers, Texas Heart Institute, 2015.
4American Heart Association. "Arrhythmia Medications" Available at: PreventionTreatmentofArrhythmia/Medications-for-Arrhythmia_UCM_301990_Article.jsp Copyright, 2015.
5WebMD 2016 Heart Disease and Calcium Channel Blocker Drugs. Conditions, side effects, food and drug interactions.
6Homoud MK Introduction to Antiarrhythmic Agents. Tufts-New England Medical Center 2008. Living your best life while taking blood thinners. National Blood Clot Alliance.
8UofChicago Medicine. Atrial Fibrillation. © University of Chicago Medicine, 2018.
9Chao TF Liu CJ et al. Rate-Control Treatment and Mortality in Afib. AHA Circulation 2015.
10UofUtah. Catheter Ablation Better Than Traditional Drug Therapies for Treating Afib. 2017.

Caution: US law restricts this device to sale by or on the order of a physician. Important information: Prior to use, refer to the instructions for use supplied with this device for indications, contraindications, side effects, warnings and precautions.

The NAVISTAR® THERMOCOOL®, EZ STEER® THERMOCOOL® NAV, THERMOCOOL® SF NAV, and THERMOCOOL SMARTTOUCH® Catheters are FDA approved for the treatment of drug refractory recurrent symptomatic paroxysmal atrial fibrillation, when used with compatible three-dimensional electroanatomic mapping systems. Catheter ablation for AF may not be an option for you if you have any of the following conditions: certain recent heart surgery; prosthetic valves; active systemic infection; certain cancers; intracardiac thrombus, or an interatrial baffle or patch. Consult your physician to find out if catheter ablation is right for you.

As with any medical treatment, individual results may vary. Only a cardiologist or electrophysiologist can determine whether ablation is an appropriate course of treatment. There are potential risks including bleeding, swelling or bruising at the catheter insertion site, and infection. More serious complications are rare, which can include damage to the heart or blood vessels; blood clots (which may lead to stroke); heart attack, or death. These risks need to be discussed with your doctor and recovery takes time.

THERMOCOOL® Navigation Catheters are indicated for the treatment of recurrent drug/device refractory sustained monomorphic ventricular tachycardia (VT) due to prior myocardial infarction (MI) in adults.