Biatrial Enlargement Etiologies
Biatrial enlargement most commonly reflects chronic elevation of left-sided filling pressures with secondary right-sided pressure/volume effects, or chronic atrial volume overload from systemic and pulmonary causes.
Left-Sided Causes
- Mitral valve disease (mitral stenosis and mitral regurgitation), which increases left atrial pressure and promotes left atrial enlargement that can extend to right atrial enlargement over time [No citation].
- Heart failure with preserved or reduced ejection fraction, which increases left atrial pressure and duration of atrial stretch [No citation].
- Systemic hypertension, which can cause chronic diastolic dysfunction and left atrial enlargement [No citation].
Right-Sided and Pulmonary Vascular Causes
- Pulmonary hypertension (any cause), which increases right atrial pressure and promotes right atrial enlargement; combined with concomitant left-sided disease can produce biatrial enlargement [No citation].
- Chronic lung disease with hypoxic pulmonary vasoconstriction (eg, COPD, interstitial lung disease), which can lead to pulmonary hypertension and right atrial enlargement [No citation].
- Chronic thromboembolic pulmonary hypertension, which increases pulmonary vascular resistance and right atrial size [No citation].
Atrial Pressure/Volume Overload and Secondary Mechanisms
- Chronic atrial fibrillation, which is associated with atrial remodeling and can coexist with or worsen atrial enlargement of both chambers [No citation].
- Congenital and valvular lesions causing chronic volume overload (eg, long-standing left-to-right shunts), which can enlarge both atria through sustained chamber loading [No citation].
Practical Clinical Associations to Prioritize
- Combined valvular disease (mitral and tricuspid), which commonly produces both left and right atrial enlargement through paired left and right filling pressure increases [No citation].
- Hypertrophic or infiltrative cardiomyopathies (eg, cardiac amyloidosis), which can produce restrictive physiology and marked atrial enlargement of both chambers [No citation].
Differential Considerations
- False-positive biatrial enlargement on electrocardiography can occur due to electrode placement issues or baseline abnormalities; echocardiography is required to confirm true atrial enlargement [No citation].