Does a patient with right atrial enlargement (RAE) need an evaluation by a pulmonologist to assess for possible pulmonary involvement?

Does Right Atrial Enlargement Require Pulmonary Evaluation?

Yes, right atrial enlargement (RAE) warrants systematic evaluation for pulmonary hypertension (PH), which should include pulmonary assessment, though the initial workup is typically coordinated by cardiology rather than requiring immediate pulmonary referral.

Initial Diagnostic Pathway

RAE is a significant echocardiographic finding that suggests elevated right heart pressures and requires structured evaluation to identify the underlying cause 1. The presence of RAE is one of the key echocardiographic signs used to assign probability of pulmonary hypertension, specifically when end-systolic RA area exceeds 18 cm² 1.

The appropriate next steps depend on the complete echocardiographic assessment:

Transthoracic Echocardiography Should Evaluate:

• Tricuspid regurgitation velocity to estimate right ventricular systolic pressure 1
• Additional signs of PH including RV enlargement, RV/LV basal diameter ratio >1, interventricular septal flattening, pulmonary artery diameter >25 mm, and IVC diameter >21 mm with reduced inspiratory collapse 1
• Left heart function including systolic/diastolic dysfunction and valvular disease to exclude PH due to left heart disease (Group 2 PH) 1
• Intracardiac shunts using agitated saline contrast study 1

Risk Stratification Based on Echocardiographic Probability

The 2022 ACR guidelines provide clear criteria for PH probability that guide further evaluation 1:

High Probability PH (requires right heart catheterization):

• Peak TR velocity >3.4 m/s regardless of other findings, OR
• Peak TR velocity 2.9-3.4 m/s WITH two categories of PH signs (including RAE) 1

Intermediate Probability PH (requires right heart catheterization):

• Peak TR velocity 2.9-3.4 m/s without additional signs, OR
• Peak TR velocity ≤2.8 m/s WITH two categories of PH signs 1

Low Probability PH:

• Peak TR velocity ≤2.8 m/s without additional echocardiographic signs 1

When Pulmonologist Referral Is Indicated

Direct pulmonology involvement becomes essential when:

• Chest X-ray or CT demonstrates parenchymal lung disease (interstitial lung disease, emphysema) suggesting Group 3 PH from lung disease and/or hypoxia 1
• Pulmonary function tests show obstructive or restrictive patterns requiring assessment of contribution to PH 1
• Clinical history suggests chronic hypoxemia or sleep-disordered breathing 1
• Ventilation-perfusion scan is abnormal but chronic thromboembolic disease has been excluded, suggesting other pulmonary vascular pathology 1

Essential Complementary Testing

Beyond echocardiography, the diagnostic algorithm requires 1:

• Chest radiography: Evaluates for central pulmonary artery enlargement (>35 mm), right descending PA >15 mm in women or >16 mm in men, and parenchymal lung disease 1
• ECG: Assesses for right axis deviation, right atrial enlargement (P wave ≥2 mm in lead II), and right ventricular hypertrophy 1, 2
• Ventilation-perfusion scan: Essential to exclude chronic thromboembolic PH (Group 4), which has specific surgical treatment implications 1
• Pulmonary function tests with DLCO: Identifies obstructive/restrictive lung disease and gas exchange abnormalities 1
• Right heart catheterization: Required for definitive diagnosis before initiating PH-specific therapy in intermediate or high probability cases 1

Critical Diagnostic Considerations

Right heart catheterization is mandatory before treatment initiation to confirm mean pulmonary artery pressure ≥25 mm Hg, pulmonary vascular resistance >3 Wood units, and pulmonary capillary wedge pressure ≤15 mm Hg, which definitively establishes pulmonary arterial hypertension 1.

The transpulmonary gradient (mean PAP minus wedge pressure) distinguishes true pulmonary vascular disease from passive elevation due to left heart disease 1. This distinction is crucial because treatment approaches differ fundamentally between Group 1 (pulmonary arterial hypertension) and Group 2 (left heart disease) PH 1.

Common Pitfalls to Avoid

• Do not dismiss RAE as benign without systematic evaluation, as it has significant association with cardiac pathology and adverse outcomes 2, 3
• Do not rely solely on echocardiographic pressure estimates for treatment decisions; invasive hemodynamic confirmation is required 1
• Do not overlook left heart disease as the most common cause of elevated pulmonary pressures in general cardiology populations 1
• Do not skip ventilation-perfusion scanning even in patients with known risk factors for other forms of PAH, as chronic thromboembolic disease is potentially surgically curable 1

Coordination of Subspecialty Care

The initial evaluation is typically cardiology-driven, with pulmonology consultation integrated based on findings suggesting primary lung disease contribution 1. In patients with established Group 3 PH (lung disease-associated), co-management between cardiology and pulmonology optimizes treatment of both the underlying lung disease and its cardiovascular consequences 1.

For patients ultimately diagnosed with pulmonary arterial hypertension (Group 1), ongoing care often involves PH specialists who may be either cardiologists or pulmonologists with expertise in pulmonary vascular disease 1.