What is atrial fibrillation?
AF is the most common supraventricular arrhythmia, whose frequency increases with age. In fact, 10% of all patients age 80 and above have the condition. Atrial fibrillation is caused by irregular and accelerated electrical heart activity whose source is the upper ventricles of the heart, primarily the left ventricle. This causes the irregular ventricular heartbeat, which impacts the flow of blood from the heart and causes an abnormal pulse.
The most common conditions that occur during AF are rapid heart pounding, shortness of breath, weakness, dizziness and chest pain. AF can also be present without symptoms.
Is AF a dangerous condition?
In and of itself, AF is usually not immediately life threatening. However, it can cause very serious complications such as heart failure and dysfunction of the heart muscle (tachycardia-mediated cardiomyopathy). The most common serious complication of atrial fibrillation is the formation of blood clots in the left atrium, giving rise to the migration of clot fragments through the vascular system (termed cardioembolism). This process can lead to arterial blockage in critical organs such as the brain, causing a stroke.
What causes atrial fibrillation?
While the causes of AF are not always known, the most common causes include:
- Excessive alcohol consumption
- Physical exertion
- Heart surgery
- A wide range of heart diseases, including cardiovascular disease, heart failure, heart valve diseases, myocardial infarction, and myocarditis (inflammation of the heart muscle)
- Pericarditis (inflammation of the membranes enveloping the heart)
People with heart conditions, high blood pressure, or diabetes are at higher risk for AF.
Atrial fibrillation events
AF is classified as follows:
- Paroxysmal atrial fibrillation: manifests as periodic attacks. The heart rate returns to normal sinus rhythm within several seconds to several hours. In some cases, the attacks may last longer—up to a week.
- Persistent atrial fibrillation: AF that does not stop spontaneously, requiring electrical cardioversion therapy or medications for its termination.
- Permanent (chronic) atrial fibrillation: AF that is incessant (and cardioversion is not a viable therapeutic option).
Treatment is selected according to the type of AF, previous therapies used, risk factors for cardioembolism, and symptoms reported by the patient.
There are three primary goals in the treatment of atrial fibrillation. These are not mutually exclusive and at times must be employed simultaneously:
- Rate control: Maintains heart rate within a desirable range using medications that slow the ventricular response to AF. Occasionally, when medications are ineffective in adequately slowing the heart rate, an ablation procedure (of the conduction system) and pacemaker implantation are used.
- Rhythm control: Prevents AF and maintains regular sinus rhythm. This approach utilizes anti-arrhythmia medications of several classes.
- Prevention of cardioembolism: Prevention is mandated in all patients considered to be at increased risk for stroke related to atrial fibrillation due to a host of risk factors. These risks include advanced age, history of a prior stroke, diabetes, vascular disease, hypertension, heart failure and gender. Minimized risk of stroke is achieved by anti-coagulation medications and, especially in patients intolerant of these drugs, by catheterization techniques, using dedicated devices for left atrial appendage closure.