Cardiopulmonary exercise testing improves diagnostic specificity in patients with echocardiography-suspected pulmonary hypertension

Background: Doppler echocardiography is usually the first diagnostic investigation for patients suspected with pulmonary hypertension (PH), but it is often inaccurate when used alone, especially in mild PH.

Hypothesis: Cardiopulmonary exercise testing (CPET) may serve as a complementary tool to improve diagnostic accuracy in echocardiography-suspected "PH possible" patients.

Methods: Eighty-eight consecutive patients with suspected PH (referred to as "PH possible" hereafter) based on echocardiography were included in the study. CPET was assessed subsequently and PH was confirmed by right-heart catheterization in all subjects. We analyzed CPET data from patients and derived a CPET prediction rule to hemodynamically differentiate PH.

Results: Eighty-eight patients (27 patients with confirmed PH, and PH ruled out in 61 patients) were included in the study. Compared with non-PH patients, the PH subjects had lower peak oxygen uptake (VO₂ ), aerobic capacity (AT), peak partial pressure of end-tidal CO₂ (P_ET CO₂ ), oxygen uptake efficiency plateau (OUEP), and oxygen uptake efficiency slope (OUES), along with higher minute ventilation (VE)/carbon dioxide output (VCO₂ ) slope and lowest VE/VCO₂ (P < 0.001). VE/VCO₂ slope and AT were independent predictors of PH derived from multivariate logistic regression adjusted for age and body mass index. A score combining VE/VCO₂ slope and AT reached a high area under the curve value of 0.98. A score ≥0.5 had 95% specificity and 92.6% sensitivity for diagnosis of PH.

Conclusions: A score combining VE/VCO₂ slope and AT provides high specificity in screening out PH from a pool of echocardiography-suspected PH patients.