What are the causes and management options for atrial fibrillation?

Causes of Atrial Fibrillation

Atrial fibrillation results from both acute reversible triggers and chronic cardiovascular conditions, with the most common causes being hypertension, structural heart disease, and advancing age, though 20-45% of cases occur without identifiable heart disease. 1

Acute and Reversible Causes

AF may be triggered by temporary conditions that, when treated, can eliminate the arrhythmia 1:

• Alcohol intake ("holiday heart syndrome") 1
• Cardiac surgery (most common early postoperative complication of cardiac and thoracic surgery) 1
• Acute myocardial infarction (portends worse prognosis than preinfarct AF) 1
• Pericarditis and myocarditis 1
• Pulmonary embolism and other pulmonary diseases 1
• Hyperthyroidism and metabolic disorders 1
• Electrocution 1

Important caveat: While these are termed "reversible," long-term follow-up data showing complete cure after treatment are limited, and patients require careful monitoring for AF recurrence 1.

Chronic Cardiovascular Conditions

Most Common Structural Heart Disease Associations

Valvular heart disease (particularly mitral valve disease—the classic association) 1:

• Mitral stenosis and regurgitation
• Mitral valve prolapse (even without significant regurgitation)
• Mitral annular calcification

Hypertension (especially with left ventricular hypertrophy) 1:

• Causes ventricular diastolic dysfunction
• Leads to left atrial enlargement and reduced left atrial appendage flow velocity
• Associated with both cardioembolic and non-cardioembolic strokes 1

Coronary artery disease 1

Heart failure (both with reduced and preserved ejection fraction) 1:

• LV systolic dysfunction predicts ischemic stroke in untreated AF patients 1

Cardiomyopathies

• Hypertrophic cardiomyopathy 1
• Dilated cardiomyopathy 1
• Restrictive cardiomyopathies (amyloidosis, hemochromatosis, endomyocardial fibrosis) 1

Congenital and Other Structural Abnormalities

• Atrial septal defect (especially in adults) 1
• Cardiac tumors 1
• Constrictive pericarditis 1

Arrhythmia-Related Causes

Primary arrhythmias that can trigger AF 1:

• Wolff-Parkinson-White (WPW) syndrome
• AV nodal reentrant tachycardias
• Atrial flutter
• Sinus node disease

Critical point: Treatment of these primary arrhythmias reduces or eliminates recurrent AF 1.

Non-Cardiac Medical Conditions

Obesity (found in 25% of AF patients) 1:

• Graded increase in left atrial size as BMI increases
• Weight reduction linked to regression of LA enlargement 1

Diabetes mellitus (requiring medical treatment in 20% of AF patients) 1

Sleep apnea (especially with concurrent hypertension and diabetes) 1

Chronic obstructive pulmonary disease (10-15% of AF patients) 1

Age-Related Mechanisms

Advancing age is multifactorial 1:

• Associated with LA enlargement and reduced LAA flow velocity
• Increases prothrombin activation (prothrombotic diathesis)
• Risk factor for atherosclerosis independent of AF
• Age combined with hypertension or female gender creates particularly high stroke risk (women >75 years) 1

Lone Atrial Fibrillation (No Identifiable Cause)

30-45% of paroxysmal AF and 20-25% of persistent AF occur in younger patients without demonstrable underlying disease 1:

• Can present as isolated or familial arrhythmia 1
• Underlying disease may appear over time 1
• In elderly patients, age-related cardiac changes (increased myocardial stiffness) may be contributory even without overt disease 1

Pathophysiological Mechanisms

Complex interplay of three factors 1:

1. Left atrial/LAA stasis (reduced flow velocities, spontaneous echo contrast)
2. Endothelial dysfunction
3. Systemic and local hypercoagulability (elevated prothrombin activation fragments)

Renin-angiotensin-aldosterone system activation 1:

• Angiotensin II and aldosterone synthesized locally in atrial myocardium
• Promotes atrial dilation, fibrosis, and increased AF susceptibility
• ACE gene variants can elevate AF risk

Clinical Evaluation Priorities

Essential initial workup to identify underlying causes 1:

• Echocardiogram (detect ventricular, valvular, and atrial disease)
• Thyroid function tests (TSH measurement)
• Complete blood count
• Serum creatinine and proteinuria analysis
• Blood pressure measurement
• Fasting glucose (diabetes screening)
• Stress test (if signs or risk factors for CAD)
• Coronary angiography (if persistent LV dysfunction or myocardial ischemia signs)

Common pitfall: Failing to recognize that "silent AF" may be the underlying cause of cryptogenic strokes—consider implantable loop recorders in stroke patients without diagnosed AF 1, 2.