What is the next step in management for a patient with low normal global function, grade I diastolic dysfunction, and desaturation to 87% with exertion, suggesting pulmonary hypertension, following a stress echocardiogram with Doppler echocardiography?

Next Step in Management: Right Heart Catheterization

Based on the stress echocardiogram findings of exercise-induced pulmonary hypertension (RVSP 50 mmHg with exertion) and significant oxygen desaturation (87%), this patient requires right heart catheterization (RHC) to definitively establish the diagnosis and hemodynamic profile before initiating any pulmonary hypertension-specific therapy. 1

Rationale for Right Heart Catheterization

• Echocardiography alone is insufficient to confirm pulmonary arterial hypertension and initiate treatment, as emphasized by the American College of Cardiology guidelines. 1
• RHC is mandatory to document mean pulmonary artery pressure (mPAP) ≥25 mmHg at rest, pulmonary capillary wedge pressure (PCWP) ≤15 mmHg, and pulmonary vascular resistance (PVR) >3 Wood units to definitively establish PAH. 1
• The PVR measurement is crucial because it distinguishes passive pulmonary hypertension from intrinsic pulmonary vascular disease, which fundamentally changes management. 1

Key Echocardiographic Findings Supporting This Decision

• Exercise-induced RVSP of 50 mmHg meets criteria for exercise-induced pulmonary hypertension (EIPH), defined as PASP >50 mmHg or peak tricuspid regurgitation velocity >3.2 m/s. 2, 3
• The European guidelines specify that SPAP ≥50 mmHg with exercise is a marker of adverse outcomes and warrants further investigation. 2
• Oxygen desaturation to 87% with exertion is abnormal and suggests either pulmonary vascular disease or underlying parenchymal lung disease requiring evaluation. 2

Critical Diagnostic Distinctions to Establish

The RHC must differentiate between three possibilities:

• Group 2 PH (left heart disease): The patient has grade I diastolic dysfunction at rest, which could worsen with exercise and cause elevated pulmonary pressures through passive venous congestion. PCWP >15 mmHg would confirm this. 4, 5
• Group 1 PAH (pulmonary arterial hypertension): Elevated mPAP with normal PCWP (≤15 mmHg) and elevated PVR (>3 Wood units) would indicate intrinsic pulmonary vascular disease. 1
• Group 3 PH (lung disease): The oxygen desaturation raises concern for underlying parenchymal lung disease contributing to PH. 2

Additional Testing Required Before or Concurrent with RHC

• Ventilation-perfusion (V/Q) scan must be completed to exclude chronic thromboembolic pulmonary hypertension (CTEPH), which has sensitivity >90% and specificity >94%. 1
• Pulmonary function tests with DLCO should be obtained to evaluate for obstructive or restrictive lung disease that could explain the desaturation and contribute to PH. 1
• High-resolution chest CT may be indicated if pulmonary function tests suggest interstitial lung disease or if V/Q scan is abnormal. 2

Clinical Context and Prevalence

• The prevalence of exercise-induced pulmonary hypertension in patients undergoing clinically indicated stress echocardiography is 11.7%. 3
• Of patients with EIPH who undergo RHC, approximately 65% have abnormal hemodynamics confirmed. 3
• Age >55 years or dilated left atrium are independently associated with abnormal right heart hemodynamics (odds ratios 5.1 and 4.4, respectively). 3

Important Caveats About Exercise Echocardiography

• Exercise Doppler echocardiography is NOT recommended for screening of pulmonary hypertension in asymptomatic patients (Class III recommendation). 2
• However, in symptomatic patients with dyspnea on exertion, exercise echocardiography is valuable for identifying exercise-induced elevation in left ventricular filling pressures and pulmonary pressures. 2
• The upper normal SPAP is <35 mmHg at rest and <43 mmHg with exercise, so this patient's RVSP of 50 mmHg clearly exceeds normal limits. 2

Diastolic Dysfunction Considerations

• Grade I diastolic dysfunction at rest can progress to restrictive physiology with exercise, dramatically elevating E/e' ratio and left ventricular filling pressures. 2
• Exercise E/septal e' >13 is a marker of adverse outcomes and should be assessed if not already done. 2
• In patients with left ventricular systolic dysfunction (this patient has low-normal EF of 55%), parameters of diastolic dysfunction (E/e' ratio ≥15, DT ≤150 ms) independently predict pulmonary hypertension even after adjusting for other factors. 5

Management Algorithm After RHC

If RHC confirms Group 2 PH (elevated PCWP):

• Optimize management of diastolic heart failure with diuretics and afterload reduction. 4
• PH-specific drugs are NOT recommended for Group 2 PH outside clinical trials, as there is no clear evidence of benefit. 4

If RHC confirms Group 1 PAH (normal PCWP, elevated PVR):

• Perform acute vasoreactivity testing during RHC to determine eligibility for calcium channel blocker therapy. 1
• Initiate PAH-specific therapy based on WHO functional class and hemodynamic severity. 2

If RHC confirms Group 3 PH (lung disease):

• Treat underlying lung disease and provide supplemental oxygen as needed. 2
• PH-specific therapy is generally not indicated unless severe PAH component is present. 2

Critical Pitfall to Avoid

Do not initiate pulmonary arterial hypertension-specific therapy (endothelin receptor antagonists, phosphodiesterase-5 inhibitors, or prostacyclins) based on echocardiography alone. These medications can be harmful in patients with Group 2 PH (left heart disease) and are only indicated after hemodynamic confirmation of PAH by RHC. 1, 4