Atrial Fibrillation Causes and Risk Factors

Cardiac Causes

The European Society of Cardiology notes that valvular heart disease, especially involving the mitral valve, significantly increases atrial fibrillation risk regardless of severity but correlates with left atrial enlargement 1, 2
The American Heart Association states that coronary artery disease represents a significant risk factor, with atrial fibrillation being more common in older patients, males, and those with left ventricular dysfunction 2
Heart failure creates an arrhythmogenic substrate through structural and electrical remodeling of the atria 2, 3
The American College of Cardiology recommends considering cardiomyopathies, including hypertrophic cardiomyopathy and dilated cardiomyopathy, as associated with increased atrial fibrillation risk 2, 3

Hyperthyroidism is a significant non-cardiac cause that should always be evaluated in newly diagnosed atrial fibrillation 3
Pulmonary conditions, including pulmonary embolism, chronic obstructive pulmonary disease, and sleep apnea syndrome, can trigger atrial fibrillation 1, 2, 3
Alcohol consumption can cause atrial fibrillation through acute intake or chronic excessive use 1, 3

Structural remodeling of the atria occurs due to inflammation, fibrosis, hypertrophy, altered wall stress, and atrial dilation 4, 3, 5
Renin-angiotensin-aldosterone system activation contributes to atrial fibrillation through promotion of fibrosis, increased synthesis of TGF-beta1, release of inflammatory mediators, and oxidative stress 5

The European Heart Journal recommends always evaluating for potentially reversible causes of atrial fibrillation, particularly thyroid dysfunction, acute alcohol intake, and pulmonary conditions 1, 3
Atrial fibrillation that develops in the setting of acute myocardial infarction portends a worse prognosis compared to pre-infarct atrial fibrillation or sinus rhythm 1, 6

Acute infections, including viral and bacterial infections, are recognized as temporary causes of atrial fibrillation, alongside other conditions like excessive alcohol intake, surgery, pericarditis, myocarditis, hyperthyroidism, and pulmonary embolism 7, 8

Infections can trigger AF through inflammatory processes that create an arrhythmogenic substrate in the atria 9
Inflammation leads to structural changes in the atria including fibrosis, hypertrophy, and altered wall stress that promote AF 9
Myocarditis (inflammation of the heart muscle) caused by viral, bacterial, or other infectious agents can lead to inflammatory cardiomyopathy and increase the risk of arrhythmias including AF 10

More than 70% of AF patients are older and present with structural heart diseases including left atrial enlargement, coronary artery disease, heart failure, valvular heart diseases, and cardiomyopathies 11

Diabetes mellitus requiring medical treatment is found in 20% of AF patients and contributes to atrial damage through metabolic effects 12
Obesity (present in 25% of AF patients) promotes AF through left atrial dilation, with progressive enlargement correlating with increasing body mass index 12
Chronic obstructive pulmonary disease is found in 10-15% of AF patients 12

Acute temporary causes include excessive alcohol intake, surgery, myocardial infarction, pericarditis, myocarditis, and pulmonary embolism—successful treatment of these underlying conditions often eliminates AF 11, 13
Postoperative AF is common, occurring in 4.4% after elective colectomy, 9.2-20% after esophagectomy, and 12.6-32% after pulmonary resection 14, 15

AF prevalence increases dramatically with age: <0.5% at age 40-50 years, 4-5% at 65 years, and 12-15% at 80 years or older 11, 12
The lifetime risk of developing AF is 25% in those who reach age 40 12

The American College of Cardiology notes that AF developing during acute myocardial infarction portends worse prognosis compared to pre-infarct AF or sinus rhythm 13
The European Society of Cardiology recognizes that multiple risk factors often coexist and have additive effects on AF perpetuation—hypertension combined with age, diabetes, or obesity creates particularly high risk 11, 12