Monday, February 22, 2016
By: Anil Rajendra, MD, Cardiac Electrophysiologist with Alabama Cardiovascular Group
Atrial fibrillation (afib) is the most common arrhythmia and affects over 2.5 million Americans. It is an irregular, unorganized heart rhythm originating in the top chambers of the heart (atria). When people are in afib, there are electrical signals originating from numerous locations in the atria, causing the atria to fibrillate or “quiver” rather than contracting normally. Many, but not all, the electrical signals in the atria are passed to the lower chambers of the heart (ventricles), often causing the heart rate to be rapid and irregular.
While afib is not a fatal arrhythmia, it does carry an increased risk of other issues, of which the most concerning may be strokes. Patients with afib have a 5 times increased risk of stroke. To minimize this risk, patients are placed on anticoagulation (blood thinners) to prevent blood clots from forming in the heart.
In addition, as mentioned previously, patients tend to have fast heart rates while they are in afib. If the heart continues to beat fast for an extended period of time, then the heart muscle may weaken and lead to heart failure. Patients with heart failure often complain of swelling in their legs or abdomen and difficulty breathing, particularly with activity or when lying flat.
The exact cause of afib is unknown. We don’t know yet why one patient develops afib and another does not. However, there are many risk factors for the development of afib, including high blood pressure, sleep apnea, diabetes, heart failure, among many others. If you have these medical problems, it is important to see your doctor regularly to ensure they are being adequately treated.
Types of atrial fibrillation
Afib is categorized based on the duration of the arrhythmia, i.e. how long patients remain in afib:
Paroxysmal afib -- intermittent episodes of afib. Episodes start and stop spontaneously and can last from seconds to days. Aside from these episodes of afib, the patient is in a normal rhythm.
Persistent afib – long episodes of afib that last over a week. These episodes of afib usually do not stop on their own. Patients will need medications to terminate the episode and restore normal rhythm, or they will need to have a cardioversion, which is an electrical shock to the heart to restore a normal rhythm.
Long-standing persistent afib – extremely long duration of afib that has lasted for over 1 year at least. These patients will almost always require advance therapies to restore a normal rhythm. However, despite these advanced therapies, patients are at high risk for recurrence of afib.
Permanent afib – afib is the permanent rhythm. The patients are always in afib and no attempts are made to restore a normal rhythm.
There is a wide spectrum of symptoms that patients experience when in afib. Some patients are asymptomatic, meaning they cannot tell at all when they are in afib. For patients who do have symptoms, these symptoms can include palpitations (feeling heart racing or irregular), shortness of breath, fatigue, weakness, dizziness, poor activity tolerance, among others.
Treatment of atrial fibrillation
For patients that do not have any symptoms related to their afib, then it is not necessary to try to prevent them from having episodes of afib. Instead, it is ok to let them remain in afib and to control the heart rate. As mentioned previously, it is important to ensure the heart rate is controlled to avoid possibly developing heart failure. For patients who are symptomatic from their afib, then it is important to try to prevent them from having afib to avoid those symptoms. Medications called anti-arrhythmic drugs can be used to try to keep patients in a normal rhythm. There are a number of different anti-arrhythmic drugs and sometimes patients will have to try several different ones before finding one that works well.
For patients that do not tolerate medications well or for whom the medications are not working well, an afib ablation is a very good option. This is a procedure where the origin of the abnormal electrical impulses that start afib are targeted with a catheter. The heart muscle is either “cauterized” (radiofrequency ablation) or frozen (cryoablation).
Prevention of Stroke
As aforementioned, patients with afib are at a much higher risk of stroke. Oral anticoagulation (blood thinners) are used to minimize that risk. There are several blood thinners available on the market, including warfarin (Coumadin), dabigatran (Pradaxa), rivoraxaban (Xarelto), apixaban (Eliquis), and edoxaban (Savaysa). Blood thinners will increase one’s risk of bleeding, so patients on blood thinners need to be monitored by their physician closely.
For some patients, the risk of bleeding is too high, and they cannot take blood thinners for a long period of time. In those patients with high risk of bleeding, there is a device called the Watchman device that is available. The Watchman device is implanted inside the heart in the area where most of the blood clots form and will permanently seal off this area of the heart. Patients with a successfully implanted Watchman device, will be able to stop their blood thinner several weeks after the implant procedure.
Atrial fibrillation is a complex arrhythmia that can cause many different symptoms. If you think that you may have an irregular heart rhythm, it is important see your doctor to investigate whether you have afib. Although afib is a complex arrhythmia, it can be very well treated.