Atrial Fibrillation Causes and Risk Factors

Cardiac Structural Causes

Valvular heart disease, particularly mitral valve disease, significantly increases atrial fibrillation (AF) risk, with a strong correlation with left atrial enlargement, according to the American College of Cardiology 1, 2.
Hypertension is the most commonly encountered risk factor in patients with incident AF, associated with a 1.8-fold increase in developing new-onset AF, as reported by the American College of Cardiology 1.
Heart failure creates an arrhythmogenic substrate through structural and electrical remodeling of the atria, with extensive atrial fibrosis, representing one of the strongest predictors of AF development, as stated by the European Heart Journal 2 and the American College of Cardiology 1.
Coronary artery disease increases AF risk, particularly in older patients, males, and those with left ventricular dysfunction, according to the American College of Cardiology 1.
Cardiomyopathies, including hypertrophic cardiomyopathy, dilated cardiomyopathy, and restrictive cardiomyopathies, all significantly elevate AF risk, as reported by the European Heart Journal 2 and the American College of Cardiology 1.

Hyperthyroidism must be evaluated in every patient with newly diagnosed AF as a potentially reversible cause, with a Class I recommendation requiring thyroid function testing, as stated by the European Heart Journal 2 and the American College of Cardiology 5.
Acute alcohol intake or chronic excessive alcohol use can trigger AF, representing a modifiable risk factor, according to the American College of Cardiology 1, 5.
Acute medical conditions, such as myocardial infarction, pulmonary embolism, pneumonia, and pericarditis, can precipitate AF, as reported by the American College of Cardiology 1, 5.
Cardiothoracic surgery commonly causes postoperative AF as an early complication, according to the American College of Cardiology 1, 5.

Obesity is found in 25% of AF patients and increases risk through left atrial dilation, with a graded increase in atrial size as body mass index rises, as reported by the European Heart Journal 2 and the American College of Cardiology 5.
Diabetes mellitus requiring medical treatment is present in 20% of AF patients and contributes to atrial damage, according to the European Heart Journal 2.
Sleep apnea, especially with concurrent hypertension, diabetes, and structural heart disease, contributes to AF through apnea-induced increases in atrial pressure, atrial size, and autonomic changes, as stated by the European Heart Journal 2 and the American College of Cardiology 3.
Chronic obstructive pulmonary disease is found in 10-15% of AF patients, though it may be more a marker for general cardiovascular risk than a specific AF trigger, according to the European Heart Journal 2, 6.
Chronic kidney disease is present in 10-15% of AF patients and may increase risk of AF-related cardiovascular complications, as reported by the European Heart Journal 2, 6.

Structural atrial remodeling is the fundamental mechanism, characterized by fibrosis, enhanced connective tissue deposition, local conduction heterogeneities, and atrial dilation, as stated by the European Heart Journal 6 and the American College of Cardiology 3.
Renin-angiotensin-aldosterone system activation promotes AF through stimulation of fibrosis, production of growth-related factors, increased intracellular calcium, hypertrophy, and apoptosis, according to the American College of Cardiology 1, 7.

Advancing age is the strongest predictor, with AF prevalence increasing from <0.5% at ages 40-50 years to 5-15% at age 80 years, as reported by the European Heart Journal 2.
Male sex confers higher risk, with men affected more often than women, according to the European Heart Journal 2.
European ancestry and family history represent genetic risk factors, as stated by the American College of Cardiology 1.

The population-attributable risk analysis shows that 56% of AF cases could be explained by one or more common modifiable risk factors, suggesting prevention through blood pressure control, weight loss, and management of other risk factors may reduce AF incidence, according to the American College of Cardiology 1, 5.