What are the causes of atrial fibrillation? Atrial fibrillation, or atrial fibrillation, is a very common cardiac arrhythmia that is characterized by multiple interlacing waves of electrical activity in the atria, which can cause an atrial fibrillation rhythm of 350 beats/min or more. Atrial fibrillation can occur in the absence of significant heart disease and is called isolated atrial fibrillation, although it is often associated with an underlying cardiovascular problem. Historically, rheumatic heart disease and hyperthyroidism were the major contributors to AF, and this is still the case today in underdeveloped countries. Atrial fibrillation is complicating 9% to 22% of patients with hyperthyroidism, and a significant number of patients with recessive hyperthyroidism also develop atrial fibrillation. Cardiac causes of AF are hypertension, ischemic heart disease, heart valve disease, congestive heart failure, cardiomyopathy, and others (sinus node disease, tumors, pericarditis, etc.). In addition, atrial fibrillation can be caused by acute or temporary causes: alcohol consumption, surgery, electrocution, myocarditis, and successful treatment of the underlying disease may eliminate atrial fibrillation. Non-cardiac causes: chronic obstructive pulmonary disease, pneumonia, pulmonary embolism, electrolyte disorders, diabetes, alcoholism, vagal nerve stimulation (after diet or exercise). Atrial fibrillation can also occur secondary to other arrhythmias, such as atrial tachycardia or atrial flutter, which originate in a region of the atria and can progress gradually to atrial fibrillation. Another important factor causing atrial fibrillation is related to the complex anatomy of the atria. Natural barriers such as the tricuspid annulus or inferior vena cava formation can significantly affect the manner and rate of conduction of electrical currents in the atria. Other causes of atrial fibrillation include plant nerve dysfunction, which can occur due to sympathetic tension caused by intense exercise and mental stimulation, and vagal tension after meals and during sleep, which can also lead to atrial fibrillation. Aging is also a cause of atrial fibrillation, as age increases atrial fibrillation patients are bound to increase, which is inevitably related to aging. Another disease that has been associated with atrial fibrillation in recent years is apnea during sleep, which can lead to changes in atrial function and structure due to low oxygen and changes in negative chest pressure, resulting in atrial fibrillation.