AFib Education

Overview: Understanding AFib

Atrial fibrillation (AFib) is the most common rhythm problem of the heart. Currently, over 2.4 million people in the U.S. have been diagnosed with AFib, and since atrial fibrillation becomes more common as people age, those numbers have been projected to increase in the future.

AFib is an irregular heart rhythm in which there is chaotic electrical activity in the atria, the upper chambers of the heart. This activity causes the atria to quiver in a very fast, disorganized way rather than contract in synchrony with the ventricles, the lower chambers of the heart. In normal (sinus) rhythm, the atria help fill the ventricles with blood prior to ventricular contraction. In atrial fibrillation, the atria contribute little to filling the ventricle, and the heart works less efficiently. The irregular heart beat and pulse that occur during AFib result from irregular conduction of the chaotic atrial electrical activity to the ventricles.

Atrial fibrillation is a complex disease that affects each individual differently. The 2007 Expert Consensus Statement on the Catheter and Surgical Ablation of Atrial Fibrillation describes three categories of atrial fibrillation¹.

1. Paroxysmal -- recurrent atrial fibrillation (>2 episodes) that terminates spontaneously within seven days.
2. Persistent -- sustained beyond seven days or lasting less than seven days but necessitating pharmacological or electrical cardioversion.
3. Permanent -- atrial fibrillation that either failed cardioversion or cardioversion was not attempted.

Symptoms

Common symptoms of Afib include unpleasant palpitations, chest discomfort, lightheadedness, shortness of breath, fatigue, or even near-fainting. Some people with atrial fibrillation present without symptoms while others have debilitating symptoms that limit their quality of life. A rapid heart rate may occur in conjunction with AFib and can exacerbate symptoms. Unfortunately, controlling the rapid heart rate may not lead to a resolution of all the symptoms that occur with AFib. This is because during AFib the heart beats without atrial and ventricular synchrony, and thus the ventricles beat irregularly and not as efficiently as when in normal sinus rhythm.

Risk Factors for Stroke

Atrial fibrillation is linked to an increased risk of stroke. The most common mechanism is sluggish blood flow in the atria which then leads to the formation of blood clots. These blood clots form in the atria and can migrate from the heart to the brain to cause a stroke. There are five major predictors of stroke in patients with AFib. These predictors can be easily recalled by referring to the acronym CHADS:

• Congestive heart failure
• Hypertension (high blood pressure)
• Age greater than 75 years old (some consider age >65 an intermediate risk factor)
• Diabetes
• Stroke or transient ischemic attack (TIA) (in the past)

According to the updated (2006) National Clinical Guideline Statement jointly published by the American College of Cardiology, the American Heart Association, and the European Society of Cardiology, if you have at least one of these risk factors, Coumadin (warfarin) may be considered and is clearly beneficial when two or more risk factors are present. Also, if a patient with AFib does have a prior stroke or TIA and no other risk factors, Coumadin is recommended. Without any of the above risk factors, the patient is considered to have “Lone” atrial fibrillation and daily aspirin is sufficient. Other medical conditions like a history of gastrointestinal bleeding or other bleeding risk can affect whether or not Coumadin is recommended for you. The decision to treat with Coumadin is sometimes difficult and requires that your doctor carefully weigh the benefits of preventing a disabling stroke against the risk of bleeding.

Treatment

Besides stroke prevention, the other major treatment goals in patients diagnosed with AFib are controlling symptoms and improving quality of life. Two relevant treatment strategies are available to practitioners depending on the severity and frequency of AFib symptoms:

1. RATE CONTROL: Slowing or regulating a rapid heart rate is most appropriate in those patients with minimal to mild symptoms. Heart rate control is achieved with certain medications (beta blockers, calcium channel blockers, and digoxin).
2. RHYTHM CONTROL: Maintenance of normal sinus rhythm is the goal in those with more significant or disabling symptoms.

Rhythm control medications are available and help some patients. The goal is to decrease the frequency and duration of AFib. It is not unusual to require occasional cardioversions to restore sinus rhythm while on these medications. Rhythm control medications can be associated with side effects and may not be extremely effective over the long-term. A newly established treatment option exists for those with symptomatic AFib: a catheter-based treatment, or “ablation”. Currently, this procedure is reserved for those whose symptoms do not improve with medical management or those who fail to tolerate these medications. The most appropriate patients for this procedure have symptomatic AFib that impairs quality of life or is disabling. Current guidelines recommend a trial of at least one rhythm control medication before proceeding to an ablation. Atrial fibrillation ablation has been refined through clinical studies during the last few years and has improved in its safety and effectiveness. In the most recent clinical studies, AFib ablation has had success rates of up to 80-90% in certain patients. The good news for those with AFib is that doctors have more options today to help patients with this condition.

Having trained at leading academic medical centers that are on the cutting edge of AFib ablation procedures, Dr. VerNooy and Dr. McWilliams have collectively performed over 250 of these complex procedures. Medical literature has shown that experience in AFib ablation improves procedural success and minimizes risks. Drs. VerNooy and McWilliams customize their treatment to each individual since all patients have unique symptoms, mechanisms, and anatomy involved in their atrial fibrillation.