Atrial Fibrillation

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Out of Synch? Atrial Fibrillation: Making Sense of Chaos

Are you troubled by the irregular and fast heart rate that goes along with atrial fibrillation? You are not alone. Atrial fibrillation (afib) is one of the most common problems we see in cardiology today. A recent study showed that about one in four Americans develops atrial fibrillation at sometime during his or her lifetime.

The heart rhythm originates in the atria - the two chambers that are located atop the pumping chambers (the ventricles). The atria act as holding chambers and booster pumps, contracting about one-fifth of a second before the ventricles do.

Atrial fibrillation occurs when the normally synchronized regular rhythm in the atria becomes chaotic, rapid, and irregular, causing the walls of the atria to essentially stand still or quiver, rather than contract effectively. This does not substantially interfere with the function of the main pumps of the heart, though it does predispose the person to other problems.

Afib and Stroke Risk

The heart rate in afib usually becomes irregular and often quite rapid. Even more problematic is a tendency to form blood clots in the 'nooks and crannies' of the atria during afib. This accounts for a five-fold increased risk of stroke for people who have atrial fibrillation, and at least one other risk factor such as being over age 60, or cardiovascular conditions including high blood pressure, valvular heart problems, congestive heart failure, diabetes or coronary disease. Younger people with perfectly normal hearts and normal blood pressure do not have an increased risk for stroke with atrial fibrillation.

This risk of stroke in afib can be largely eliminated with the use of warfarin (Coumadin). If you are on warfarin, it is important to keep a close eye on the INR (protime). We like to see the INR between 2.0 and 3.0 to prevent clots without predisposing to excessive bleeding. The response to warfarin varies from one person to the next, so finding the dose right for you is a matter of monitoring the INR and adjusting the dose accordingly. Additionally, the type of diet you are eating, whether you have recently been taking antibiotics, and many other factors can affect your sensitivity to this drug.

Thus, it is very important for you to be closely monitored while you are on Coumadin. We generally have people check their INR/protime every two or three weeks to make sure they are within the desired range. If you are interested, we do have a Protime Clinic at Cardiovascular Consultants that offers this service.

No Racing!

It is also important to keep your heart from racing when in atrial fibrillation. Drugs, including beta blockers (Metoprolol, Coreg, Toprol) and calcium blockers (diltiazem, verapamil) and digoxin are helpful for preventing rapid rates in atrial fibrillation. For many afib patients we suggest electrocardioversion - a procedure that uses a controlled electric current passed through the chest during brief anesthesia to restore normal sinus rhythm. There are many drugs as well to help keep you in sinus rhythm, such as amiodarone, flecainide, proprofenone, and sotalol. These medications can have side effects and need to be monitored closely.

Several large, randomized, controlled trials have been performed in the past few years addressing the question of whether or not we should try hard to maintain a sinus rhythm (get you back in synch) or simply settle for anticoagulation and rate control without resorting to the more problematic medications and recurrent shocks to the heart. These studies show that either strategy results in similar long-term outcomes. The rhythm control strategy (employing the more dangerous medications and repeated shocks) is more expensive and has a higher risk of adverse medication effects, as well as a trend towards lower survival than rate control alone. The two largest and best studies on this issue, the AFFIRM and the RACE trials, both found that maintaining effective anticoagulation with warfarin and rate control were the most important issues for preventing problems in atrial fibrillation over the long term. Atrial fibrillation is a common and bothersome problem, but generally is not life threatening.

Options for Treatment

Because we do not have one simple and reliable solution for atrial fibrillation, there are many different options for treating this problem. Our treatment strategy focuses on the safest and most effective approach in each particular individual for minimizing the symptoms of afib and reducing risk of stroke.

One of the hot areas of research in atrial fibrillation currently involves radiofrequency ablation. This technique is being performed here at Cardiovascular Consultants by Drs. David Steinhaus and Brian Ramza. This procedure involves using advanced electrophysiologic techniques that typically take four or five hours to localize regions in the atria where the afib rhythm disturbance arises. Small controlled burns are then placed in these sites to eliminate the sources of irritability.

Recent studies show that this is a promising technique, although much work needs to be done in perfecting it before it becomes widely available. The latest studies indicate that about 75 percent of people who have afib ablation have the rhythm problem cured. We are considering afib ablation as an option for some people in whom medications have failed. However, most patients are not candidates for this procedure yet.

Preventing Afib

If you have atrial fibrillation, there are steps you can take to reduce the likelihood that this problem will occur. Make sure your blood pressure is well controlled. Recent studies suggest that some blood pressure drugs, including ACE inhibitors and angiotensin receptor blockers, may be helpful in preventing recurrent atrial fibrillation.

Studies show that Omega-3 fats (fish oil) can be helpful for preventing or reducing recurrence of atrial fibrillation. The best study on this topic was just published in the Journal of the American College of Cardiology in March 2005. In this trial, the people who were randomized to 1,700 mg. of Omega-3 per day prior to bypass surgery had a 54 percent lower risk of afib developing after surgery.

Regular exercise, keeping your weight down, avoiding excess caffeine and alcohol, making sure you get a good night's sleep, and trying to eliminate excess stress can all help to make your heart less irritable. Recent studies suggest that sleep apnea is commonly associated with atrial fibrillation. If you snore loudly, this may be predisposing you to low oxygen levels at night and triggering episodes of atrial fibrillation. Sleep apnea can also cause other problems like high blood pressure, ventricular rhythm abnormalities, and congestive heart failure, so it is important to treat this problem, if you have it.

To summarize, atrial fibrillation is an increasingly common cardiovascular problem. If you have this disorder, you need to talk to your cardiologist about options. The most important issues are to be sure that you are on anticoagulation medication, if you are a candidate for this, and to make sure that your heart rate is not more than 100 beats per minute when you are in afib.

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