What group of pulmonary hypertension is caused by severe tricuspid (TR) regurgitation?

Pulmonary Hypertension Classification in Severe Tricuspid Regurgitation

Severe tricuspid regurgitation (TR) causes post-capillary pulmonary hypertension, which is classified as Group 2 pulmonary hypertension according to the ESC/ERS guidelines. 1

Understanding the Classification

The ESC/ERS guidelines classify pulmonary hypertension into 5 distinct groups based on etiology:

1. Group 1: Pulmonary arterial hypertension
2. Group 2: PH due to left heart disease
3. Group 3: PH due to lung diseases and/or hypoxia
4. Group 4: Chronic thromboembolic PH and other pulmonary artery obstructions
5. Group 5: PH with unclear and/or multifactorial mechanisms

Hemodynamic Classification

Severe TR leads to post-capillary pulmonary hypertension, characterized by:

• Mean pulmonary arterial pressure (mPAP) ≥25 mmHg
• Pulmonary arterial wedge pressure (PAWP) >15 mmHg 1

Pathophysiological Mechanism

The development of pulmonary hypertension in severe TR follows this sequence:

1. Severe TR causes right atrial enlargement and increased right atrial pressure
2. This elevated pressure is transmitted backward into the pulmonary venous system
3. The increased pulmonary venous pressure leads to pulmonary congestion
4. Over time, this causes pulmonary vascular remodeling and pulmonary hypertension

Clinical Implications

Severe TR with pulmonary hypertension significantly impacts prognosis:

• Patients with severe TR and concomitant pulmonary hypertension have higher mortality rates (58.2% vs. 43.6% 5-year mortality) 2
• Severe TR is strongly predictive of greater 5-year mortality risk (adjusted hazard ratio, 1.83) 3
• The combination of severe TR and pulmonary hypertension leads to more pronounced right ventricular dysfunction 4

Diagnostic Approach

When evaluating pulmonary hypertension in severe TR:

1. Echocardiography: First-line diagnostic tool

   • Assess TR severity
   • Estimate pulmonary artery pressure using TR velocity
   • Evaluate right ventricular size and function

2. Right heart catheterization: Gold standard for confirmation

   • Measures mean pulmonary artery pressure (mPAP ≥25 mmHg)
   • Determines pulmonary arterial wedge pressure (PAWP >15 mmHg in post-capillary PH)
   • Calculates pulmonary vascular resistance (PVR)

Important Considerations

• The accuracy of echocardiographic diagnosis of pulmonary hypertension in severe TR may be limited (only 55% accuracy) 4
• Discordance between invasive and echocardiographic measurements of pulmonary hypertension in severe TR carries the highest risk for poor outcomes 4
• Severe TR may be reversible in some cases if the underlying cause (such as right ventricular ischemia or tachycardia) is addressed 5, 6

Management Implications

Understanding that severe TR causes Group 2 pulmonary hypertension guides management:

• Treatment should focus on addressing the tricuspid valve pathology
• Tricuspid valve repair or replacement should be considered for severe TR, especially when associated with symptoms or progressive right ventricular dilation/dysfunction 1
• In patients undergoing left-sided valve surgery, concomitant tricuspid valve repair should be performed if severe TR is present 1

Remember that severe TR with pulmonary hypertension represents advanced disease with poor prognosis, warranting careful evaluation and timely intervention.