Timing of Right Heart Catheterization in Systemic Sclerosis with Suspected Pulmonary Hypertension
Right heart catheterization should be performed now, before initiating systemic sclerosis therapy, as early diagnosis of pulmonary hypertension is critical for mortality reduction and the presence of interstitial lung disease does not preclude immediate evaluation.
Rationale for Immediate Right Heart Catheterization
The diagnostic workup for pulmonary hypertension should not be delayed by initiation of systemic sclerosis therapy. Pulmonary arterial hypertension is the single most common cause of disease-related death in systemic sclerosis, with dramatic impact on prognosis and survival 1. Early confirmation of PAH diagnosis by right heart catheterization is necessary when echocardiography raises suspicion 1.
Key Supporting Evidence
Echocardiography has high sensitivity (90%) but moderate specificity (75%) for detecting pulmonary hypertension in systemic sclerosis, meaning that while it reliably identifies most cases, confirmation by RHC is essential to avoid unnecessary treatment 2.
The presence of NSIP on chest CT does not contraindicate or delay right heart catheterization. In fact, patients with systemic sclerosis and interstitial lung disease who have suspected PH require hemodynamic confirmation to guide appropriate therapy 3.
Delaying RHC until after starting immunosuppression for systemic sclerosis would postpone critical diagnostic and therapeutic decisions for a potentially fatal complication that requires specific PAH-targeted therapies distinct from systemic sclerosis treatment 1.
Clinical Algorithm for Proceeding with RHC
Step 1: Confirm Echo Findings Are at Steady State
Ensure the echocardiogram was obtained during clinical stability, not during acute illness or exacerbation of systemic sclerosis or interstitial lung disease 4.
Consider repeating the echocardiogram if there is uncertainty about the clinical state at the time of the initial study, as reproducibility of measurements may vary 4.
Step 2: Obtain Additional Risk Stratification
Before proceeding to RHC, obtain:
6-minute walk distance (6MWD): A distance <333 meters in adults with connective tissue disease suggests higher likelihood of confirmed PAH and supports proceeding with RHC 4.
NT-proBNP or BNP levels: Values ≥160 pg/mL increase diagnostic accuracy for PAH and support RHC referral 4.
These additional markers improve diagnostic yield and help justify the invasive procedure, particularly when echocardiographic findings are in the borderline range 4.
Step 3: Multidisciplinary Consultation
Consult with a pulmonary hypertension specialist, cardiologist, or pulmonologist before scheduling RHC to ensure appropriate patient selection and interpretation of results 4.
This consultation should occur now, not after starting systemic sclerosis therapy, as the PH expert can help determine urgency and guide the diagnostic approach 4.
Step 4: Comprehensive Pre-RHC Evaluation
While scheduling RHC, complete the following studies to characterize the type of pulmonary hypertension:
Ventilation-perfusion (V/Q) scan to exclude chronic thromboembolic pulmonary hypertension, which would require entirely different management 5.
High-resolution CT chest (already completed in this case showing NSIP) to assess for pulmonary veno-occlusive disease (PVOD), which is a critical exclusion as PAH-specific vasodilators can cause fatal pulmonary edema in PVOD 5.
Pulmonary function tests including DLCO, as this is one of the most important variables for predicting PAH in systemic sclerosis 6.
Bubble study with echocardiography to evaluate for intracardiac shunts that may contribute to or complicate pulmonary hypertension 7.
Critical Considerations Specific to This Case
The Presence of NSIP Does Not Change the Timing
Patients with systemic sclerosis can have both interstitial lung disease and pulmonary arterial hypertension simultaneously, and these require different therapeutic approaches 3.
A vasoreactivity test using inhaled nitric oxide during RHC may be particularly helpful in patients with both PH and severe interstitial lung disease to determine if they will respond to PH-targeted therapy 3.
Hemodynamic assessment is essential to distinguish PAH (precapillary PH) from pulmonary hypertension due to left heart disease (postcapillary PH), as treatment differs substantially 8.
Defining Pulmonary Hypertension on RHC
When RHC is performed, pulmonary hypertension is defined as:
Mean pulmonary artery pressure >20 mmHg (updated threshold from the previous 25 mmHg) 4.
For pulmonary arterial hypertension specifically: pulmonary artery wedge pressure ≤15 mmHg AND pulmonary vascular resistance ≥3 Wood units 4.
These hemodynamic criteria are essential for determining appropriate therapy and cannot be reliably established without invasive measurement 4.
Why Not Wait Until After Starting Systemic Sclerosis Therapy?
Mortality Implications
PAH in systemic sclerosis has high morbidity and mortality that requires prompt, specific intervention with PAH-targeted therapies 4, 1.
Immunosuppressive therapy for systemic sclerosis does not treat PAH, and delaying PAH diagnosis means delaying life-saving PAH-specific medications 1.
Treatment Strategy Depends on RHC Results
If PAH is confirmed, patients require PAH-specific therapies (prostacyclin analogues, endothelin receptor antagonists, phosphodiesterase-5 inhibitors) in addition to systemic sclerosis treatment 1.
If postcapillary PH is found, management focuses on optimizing left heart function rather than PAH-specific drugs 8.
If PH is ruled out, this avoids unnecessary exposure to PAH medications and their potential side effects 4.
Baseline Hemodynamics Are Important
- Establishing baseline hemodynamics before starting any therapy allows for accurate assessment of treatment response to both systemic sclerosis therapy and any subsequent PAH-specific therapy 4.
Common Pitfalls to Avoid
Do Not Delay RHC Based on Interstitial Lung Disease
The most critical pitfall is assuming that dyspnea and elevated pulmonary pressures are solely due to NSIP without confirming the hemodynamic profile 3.
Patients with systemic sclerosis and ILD can have coexistent PAH that requires specific treatment 3.
Do Not Start PAH Therapy Without RHC Confirmation
Never initiate PAH-specific vasodilators based on echocardiography alone, as the false-positive rate is significant and these medications have substantial side effects and costs 4, 2.
If PVOD is present (suggested by ground glass opacities with septal lines on HRCT), PAH-specific vasodilators are contraindicated due to risk of life-threatening pulmonary edema 5.
Do Not Perform RHC at a Non-Expert Center
- Mortality in severe PAH managed at non-expert centers is significantly higher, so referral to a specialized pulmonary hypertension center is essential 5.
Practical Next Steps
Schedule right heart catheterization at a specialized PH center now 5.
Complete V/Q scan, bubble study, PFTs with DLCO, and autoimmune serologies while awaiting RHC 5, 7, 6.
Obtain 6MWD and NT-proBNP to further support the indication for RHC 4.
Proceed with systemic sclerosis therapy planning in parallel, but do not delay RHC for this purpose 1.
After RHC confirms diagnosis and type of PH, implement appropriate PAH-specific therapy under PH specialist guidance while simultaneously treating the underlying systemic sclerosis 1.