Detection of exercise-induced pulmonary arterial hypertension by cardiopulmonary exercise testing

BACKGROUND: The pulmonary arterial pressure (PAP) response to exercise may provide a tool for the early detection of pulmonary arterial hypertension (PAH). Therefore, an accurate noninvasive method for evaluating exercise-induced PAH (EIPAH) is desirable.

HYPOTHESIS: We sought to examine if cardiopulmonary exercise testing (CPET) is able to indicate EIPAH.

METHODS: Fifty-three patients aged 67.1 ± 1.7 years (37 female, 16 male) with borderline PAH (resting mean PAP 21-24 mm Hg) performed CPET and right heart catheterization at rest and during handgrip testing.

RESULTS: When comparing patients with an exercise-induced mean PAP ≥ mm Hg (group A, n = 24) and subjects with an exercise-induced mean PAP <35 mm Hg (group B, n = 29), group A had a significantly lower mean aerobic capacity (15.2 ± 1.2 vs 19.7 ± 1.2 mL/min/kg; P = 0.02), higher ventilatory equivalents for oxygen at the anaerobic threshold (34.3 ± 1.5 vs 29.9 ± 1.1; P = 0.02), a widening of the mean alveolar-arterial oxygen difference (37.8 ± 3.0 vs 26.8 ± 2.4 mm Hg; P = 0.007), an elevated mean functional dead space ventilation (29.5 ± 2.7 vs 21.2 ± 1.7%; P = 0.008), and a higher mean arterial to end-tidal carbon dioxide gradient at peak exercise (3.7 ± 0.9 vs 0.4 ± 0.8 mm Hg; P = 0.007).

CONCLUSIONS: EIPAH is characterized by a decreased ventilatory efficiency due to ventilation to perfusion inequalities. CPET may be useful for the identification of EIPAH and serve to diagnose PAH at an early stage.