Left Atrial Enlargement

Gregory Kicska, MD, PhD

DIFFERENTIAL DIAGNOSIS

Common

Left Heart Failure
Mitral Valve Disease
Chronic Atrial Fibrillation

Less Common

Left to Right Shunts

Rare but Important

Constrictive Pericarditis/Restrictive Cardiomyopathy

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Radiograph: Double density sign, splaying of carina, superior displacement of left main bronchus, posterior esophageal displacement, enlarged LA appendage
Aortic root diameter: LA short axis ratio should be near 1:1
Rightward displacement of interatrial septum suggests LA enlargement
Normal volume = 22 ± 5 mL/m²

Helpful Clues for Common Diagnoses

Left Heart Failure
- Chronic ischemia, diabetes, and chronic hypertension most common etiologies
- Diastolic heart failure can exist with normal LV end diastolic volume and ejection fraction
Mitral Valve Disease
- Stenosis
  - Coexistent edema suggests valve area is less than 1 cm² (normal 4-6 cm²)
  - Calcified leaflets not to be confused with mitral annular calcification
- Regurgitation
  - Often coexists with stenosis and calcified valve
  - Absence of calcifications suggests prolapse or ruptured papillary muscle
Chronic Atrial Fibrillation
- Exclude LA appendage thrombus on contrast exams
- Senescent dilation may lead to A-fib

Helpful Clues for Less Common Diagnoses

Left to Right Shunts
- Qp:Qs ratio does not equal 1
- VSD does not cause LA dilation unless large
- ASD only with Eisenmenger physiology in advanced age
- PDA will also have LV enlargement

Helpful Clues for Rare Diagnoses

Constrictive Pericarditis/Restrictive Cardiomyopathy
- Tubular-shaped ventricles are disproportionally smaller than atria
- Constrictive pericarditis suggested by focal or diffuse pericardial thickening > 4 mm or calcification in presence of heart failure
- Restrictive cardiomyopathy suspected in absence of pericardial thickening

Image Gallery

Frontal radiograph shows cardiomegaly with left atrial and ventricular enlargement in a patient with heart failure. Note splaying of the carinal angle (normal < 90°)