Risk Factors for Atrial Fibrillation
The major risk factors for atrial fibrillation include advancing age, hypertension, heart disease (especially valvular heart disease, heart failure, and coronary artery disease), obesity, and metabolic disorders such as hyperthyroidism and diabetes. 1
Established Risk Factors
Demographic Factors
- Age: Risk doubles with each advancing decade of age, from 0.5% at age 50-59 years to almost 9% at age 80-89 years 2
- Male sex: Men have a 1.5-fold greater risk than women after adjustment for age and predisposing conditions 2
- Female sex over 75 years: Particularly high risk for cardioembolic strokes 1
Cardiovascular Conditions
- Hypertension: Increases risk 1.4-1.5 fold and is responsible for more AF in the population (14%) than any other risk factor 2
- Heart failure: Increases risk 4.5-5.9 fold 2
- Valvular heart disease: Especially mitral valve disease, increases risk 1.8-3.4 fold 2, 1
- Coronary artery disease: Increases risk by 40% in men 2
- Left ventricular hypertrophy: Associated with hypertension 1
- Cardiomyopathies: Including hypertrophic cardiomyopathy and dilated cardiomyopathy 1
- Congenital heart disease: Especially atrial septal defect in adults 1
Metabolic and Other Medical Conditions
- Obesity: Important risk factor mediated through left atrial dilation 1
- Diabetes: Increases risk 1.4-1.6 fold 2
- Hyperthyroidism: Significant metabolic trigger 1
- Sleep apnea syndrome: Common comorbidity with AF 1
Structural Cardiac Changes
- Left atrial enlargement: 39% increase in risk per 5-mm increment 2
- Decreased left ventricular function: 34% risk increase per 5% decrement in fractional shortening 2
- Increased left ventricular wall thickness: 28% risk increase per 4-mm increment 2
Temporary or Acute Causes
- Alcohol consumption: "Holiday heart syndrome" 1
- Surgery: Especially cardiac and thoracic surgery 1
- Acute myocardial infarction: Associated with worse prognosis 1
- Pericarditis/Myocarditis: Inflammatory cardiac conditions 1
- Pulmonary embolism: And other acute pulmonary diseases 1
- Electrocution: Can trigger AF 1
Emerging Risk Factors
- Familial/Genetic factors: AF can present as an isolated or familial arrhythmia 1
- Autonomic influences: Play an important role in AF initiation 1
- Prehypertension and increased pulse pressure 3
- High-level physical training: Endurance exercise 3
- Diastolic dysfunction 3
Lone Atrial Fibrillation
- Approximately 30-45% of paroxysmal AF cases and 20-25% of persistent AF cases occur in younger patients without demonstrable underlying disease ("lone AF") 1
- May be related to undiagnosed conditions that appear over time 1
Risk Factors for Drug-Induced Atrial Fibrillation
Certain medications can induce AF, particularly in patients with:
- Previous history of AF
- Advanced age
- Hypertension
- Coronary artery disease
- Left atrial enlargement 1
Clinical Implications
Understanding these risk factors is crucial because:
- Many risk factors are modifiable (hypertension, obesity, sleep apnea)
- Weight reduction has been linked to regression of left atrial enlargement, potentially decreasing AF risk 1
- Risk factor identification helps determine stroke prevention strategies using risk stratification tools like CHADS2 1
Prevention Strategies
- Blood pressure control: Critical for reducing AF risk
- Weight management: Can reduce left atrial size and AF burden
- Treatment of underlying conditions: Particularly thyroid disorders, sleep apnea
- Moderation of alcohol intake: To prevent acute AF episodes
- Early intervention for heart disease: Especially valvular and coronary artery disease
Recognizing and addressing these risk factors can help prevent the development of AF and its complications, including stroke, heart failure, and increased mortality.