Atrial Fibrillation also known as AF, A Fib or AFib is the most common sustained arrhythmia in the United States. Currently it affects 2.5-3 million Americans, by 2020 7.5-10 million Americans will be diagnosed with Atrial Fibrillation. It is characterized by a rapid and disorganized (chaotic) heart beat within the two top chambers of the heart or the atria. The atria can beat 300 beats per minute and the bottom chambers can follow along at roughly half as fast.
Atrial Fibrillation can be associated with palpitations, heart awareness, and rapid heartbeat, shortness of breath, chest discomfort, fatigue, and difficulty in performing vigorous exercise. Surprisingly, 50% of patients have minimal or no symptoms and the remaining 50% of patients may have debilitating symptoms.
Atrial fibrillation is associated with a two-fold increase in death when compared to patients without this arrhythmia. The main life threatening issue is related to thromboembolism (clots) from the heart which may migrate to the brain and cause a stroke. These clots can travel to the other distant arterial vasculature such as the arteries of the legs, or the gut arteries.
The precise mechanisms of Atrial Fibrillation remain poorly understood. Atrial Fibrillation is triggered by pulmonary vein firing within the left atrium of the heart. Typically most people of have four pulmonary veins. Caffeine, alcohol, and stress may cause the pulmonary veins to fire rapidly and cause an Atrial Fibrillation episode. Why one patient’s pulmonary veins fire and another’s do not remains uncertain.
Typically Atrial Fibrillation goes through several phases after diagnosis; initially it often comes and goes, from relatively short bursts of Atrial Fibrillation alternating with normal heartbeats. Over time the episodes of Atrial Fibrillation may become longer and require intervention such as medicine or electrical Cardioversion (shock) to restore normal rhythm. Atrial Fibrillation which is permanent is every beat of every day for more than a year in duration. Medications and interventional treatment are most effective in the earlier phases of the disease process.
Anticoagulation is necessary to prevent thromboembolic complications. Some patients can be treated with aspirin; many patients will require higher intensity blood thinning. Currently there are four anticoagulation drugs and each has pros and cons.
Atrial Fibrillation cases begin to increase after the age of 65; approximately one in five patients above the age of 55 will develop Atrial Fibrillation over their lifetime. By the age of 80, one in four patients will have atrial fibrillation. Patients who have associated medical conditions such as obesity, sleep apnea, congestive heart failure, diabetes mellitus, hypertension, and vascular disease are more likely to develop Atrial Fibrillation Some patients have none of these associated medical conditions and have the so-called “lone” Atrial Fibrillation.
For those who do not have symptoms or have minimal symptoms, traditionally an appropriate blood thinner is selected and medications are used to manage Atrial Fibrillation. Some medications that are used are beta blockers to slow down the heart rate, calcium channel blockers, and digoxin. This treatment paradigm is called the rate control strategy.
Again, an appropriate blood thinner is selected to reduce the risk of thromboembolic (clot) complications. Antiarrhythmic drugs are utilized to suppress the regions within the atria (top chambers) which can fire and cause Atrial Fibrillation. Typical antiarrhythmic medications are flecainide, propafenone, dronedarone, sotalol, dofetilide, and amiodarone. Your doctor will chose one of these drugs depending upon your individual medical history. All of these medications are cleared out (metabolized) by the body via either the liver or kidneys. All these medications have side effects.
The main interventional or treatment option for Atrial Fibrillation is catheter ablation. This involves burning inside the heart within the regions believed to cause the episodes of Atrial Fibrillation. Catheter ablation (Atrial Fibrillation ablation) is most effective in restoring normal rhythm in patients with paroxysmal Atrial Fibrillation. The procedure is lengthy, 3-4 hours, and is often performed using general anesthesia. The procedure does have risks, including perforation of the heart, death, and stroke. The success rate for the catheter ablation procedure is 70-80% reduction in the AF burden after one procedure (amount of Atrial Fibrillation). However, there is a 30% risk of needing an additional procedure over time.