Causes of Atrial Fibrillation
Atrial fibrillation is predominantly caused by underlying cardiovascular disease in 70-80% of cases, with hypertension, coronary artery disease, heart failure, and valvular heart disease being the most common culprits. 1
Cardiovascular Causes
The most frequent cardiac conditions that cause atrial fibrillation include:
- Hypertension is the leading cause, particularly when left ventricular hypertrophy develops, creating an arrhythmogenic substrate through elevated atrial pressure and diastolic dysfunction 1, 2
- Coronary artery disease promotes atrial fibrillation through atrial ischemia and structural remodeling; when atrial fibrillation develops during acute myocardial infarction, it signals particularly poor prognosis 1, 2
- Heart failure with either systolic or diastolic dysfunction causes elevated atrial pressure and is strongly associated with atrial fibrillation development 1, 2
- Valvular heart disease, especially mitral valve disease (stenosis or regurgitation), is common regardless of severity but correlates with left atrial enlargement 1, 2
- Cardiomyopathies including hypertrophic cardiomyopathy and dilated cardiomyopathy create structural abnormalities that predispose to atrial fibrillation 2
Acute and Reversible Causes
Certain conditions trigger atrial fibrillation that may resolve with treatment of the underlying cause:
- Alcohol intake ("holiday heart syndrome") is a well-recognized acute precipitant 1, 2
- Hyperthyroidism and metabolic disorders can trigger atrial fibrillation that resolves with treatment 1, 2
- Acute cardiac conditions including myocardial infarction, pericarditis, myocarditis, and cardiac surgery 2, 1
- Pulmonary conditions such as pulmonary embolism and other acute pulmonary diseases 2
- Electrocution can acutely trigger atrial fibrillation 2
Additional Medical Conditions
Several other conditions increase atrial fibrillation risk:
- Obesity promotes atrial fibrillation through progressive left atrial dilation that correlates with increasing body mass index 1
- Sleep apnea syndrome is commonly associated with atrial fibrillation, likely through hypoxia-mediated autonomic dysregulation and altered atrial tissue properties 1, 3
- Diabetes increases risk, particularly in women 4, 5
- Chronic kidney disease contributes through volume overload and uremic toxins 3
- Congenital heart disease, especially atrial septal defect in adults 2, 4
Lone/Idiopathic Atrial Fibrillation
A substantial minority of cases occur without identifiable structural heart disease:
- 30-45% of paroxysmal atrial fibrillation and 20-25% of persistent atrial fibrillation occur in younger patients without demonstrable underlying disease 1, 2
- Familial atrial fibrillation suggests genetic susceptibility, with increased likelihood among offspring of parents with atrial fibrillation 1
- The term "lone atrial fibrillation" applies when hyperthyroidism, chronic obstructive lung disease, sinus node dysfunction, and Wolff-Parkinson-White syndrome have been excluded 4, 5
Age-Related Risk
Age is a powerful independent risk factor:
- Prevalence increases dramatically in the seventh and eighth decades of life, affecting 3-5% of the population over 60 years 5, 6
- Aging is associated with left atrial enlargement, reduced left atrial appendage flow velocity, age-related atrial fibrosis, and prothrombotic changes 2, 3
Critical Clinical Pitfall
Search for predisposing conditions in every patient presenting with atrial fibrillation, as successful treatment of underlying causes often eliminates the arrhythmia. 1 This is particularly important for reversible causes like hyperthyroidism, acute alcohol intake, and acute cardiac conditions that may not require long-term rhythm management if the underlying trigger is addressed.