What are the common causes of atrial fibrillation in the elderly?

Causes of Atrial Fibrillation in the Elderly

In elderly patients, atrial fibrillation results primarily from age-related cardiac structural changes combined with accumulated cardiovascular disease burden, most commonly hypertension with left ventricular hypertrophy, coronary artery disease, heart failure, and valvular disease—particularly mitral valve pathology. 1

Age-Related Structural Changes

The aging heart undergoes fundamental changes that create an arrhythmogenic substrate independent of overt disease:

• Atrial fibrosis develops progressively, with the aging heart losing approximately 0.5-1.0% of cardiomyocytes per year, replaced by fibrous tissue that disrupts electrical coupling and creates heterogeneous conduction 1
• Increased myocardial stiffness accompanies aging and directly contributes to AF development, even in elderly patients without demonstrable heart disease 1
• Left atrial dilation occurs as a consequence of aging-related structural remodeling, creating the substrate for sustained AF 1

Cardiovascular Diseases Associated with AF in the Elderly

Hypertension and Left Ventricular Hypertrophy

• Hypertension, particularly when left ventricular hypertrophy is present, represents one of the most common causes of AF in elderly patients 1
• The risk increases substantially when hypertension is longstanding, allowing time for structural atrial changes to develop 2, 3

Coronary Artery Disease

• CAD is explicitly listed as a major cardiovascular condition associated with AF, promoting arrhythmia through atrial ischemia, structural remodeling, and increased left atrial pressure 4
• When AF develops during acute myocardial infarction, it portends particularly poor prognosis compared to patients maintaining sinus rhythm 1, 4

Heart Failure

• Heart failure both promotes AF and is worsened by AF, with the 3-year incidence of AF approaching 10% in patients treated for heart failure 1
• Left ventricular systolic dysfunction predicts AF development and creates a bidirectional relationship where each condition aggravates the other 1

Valvular Heart Disease

• Mitral valve disease represents the most common valvular etiology, with AF occurrence more common in patients with enlarged left atrium and congestive heart failure rather than correlating with stenosis severity 1, 2
• Other valvular pathologies including mitral valve prolapse, calcification of the mitral annulus, and aortic stenosis are associated with increased AF incidence 5, 2

Other Cardiac Conditions

• Cardiomyopathies including hypertrophic cardiomyopathy, dilated cardiomyopathy, and restrictive cardiomyopathies (amyloidosis, hemochromatosis, endomyocardial fibrosis) predispose to AF 1
• Congenital heart disease, especially atrial septal defect in adults, carries high AF incidence 1
• Sleep apnea syndrome is commonly encountered, though whether provoked by hypoxia, biochemical abnormalities, pulmonary dynamics changes, or autonomic tone alterations remains undetermined 1

Reversible and Acute Causes

Always screen for reversible causes as successful treatment often eliminates AF:

• Hyperthyroidism and other metabolic disorders should be ruled out in every instance of newly discovered AF 1, 2
• Acute conditions including alcohol intake ("holiday heart syndrome"), pulmonary embolism, pericarditis, myocarditis, and acute myocardial infarction 1
• Postoperative AF commonly occurs after cardiac and thoracic surgery 1
• Drug-induced AF from cardiovascular, non-cardiovascular, and particularly anticancer drugs represents an increasingly recognized cause, especially in elderly patients on polypharmacy 1

Medical Comorbidities

• Obesity is an important risk factor, with excess AF risk mediated by left atrial dilation that increases progressively from normal to overweight to obese categories 1
• Diabetes mellitus serves as an important predictive factor for AF development 2, 3
• Chronic kidney disease contributes through maladaptive mechanisms 1

Lone Atrial Fibrillation in the Elderly

• Approximately 20-25% of persistent AF cases occur without demonstrable underlying disease ("lone AF"), though this percentage is lower in elderly compared to younger patients 1
• A causal underlying disease may appear over time in patients initially classified as having lone AF, making the distinction less clear in elderly populations 1

Critical Clinical Pitfalls

The longer time period during which risk factors operate in elderly patients allows cumulative structural changes that ultimately manifest as AF, partially explaining the strong age-AF association 6. Do not dismiss new-onset AF as merely coincidental to underlying conditions—it represents active disease interaction requiring aggressive management of both AF and its underlying causes 4. Women over age 75 with AF face particularly high stroke risk, making recognition and anticoagulation decisions especially critical 1.