Differences in pulmonary function and exercise capacity in patients with idiopathic dilated cardiomyopathy and idiopathic pulmonary arterial hypertension

Objectives

We observed the pulmonary function and exercise capacity of idiopathic dilated cardiomyopathy (IDCM) and idiopathic pulmonary arterial hypertension (IPAH) patients using cardiopulmonary exercise testing (CPX). We evaluated and compared the two groups.

Background

Pulmonary abnormalities and decreased exercise capacity are common in IDCM and IPAH. Little is known about the differences in these two syndromes.

Methods

Sixty-three patients were involved the study, 23 with IDCM and 40 with IPAH. All patients underwent pulmonary function testing at rest and CPX.

Results

Patients with IPAH had a higher peak respiratory frequency (32.40 ± 7.88 vs 29.60 ± 6.50 b/min), peak dead space volume/tidal volume (29.33 ± 4.55 vs 26.30  ± 3.31%), peak end-tidal partial pressure of O₂ (125.18 ± 5.88 vs 115.17 ± 6.06 mm Hg), peak minute ventilation/CO₂ production (50.14 ± 13.26 vs 33.50 ± 6.80 L/min/L/min), and a lower peak oxygen uptake (1262.70 ± 333.34 vs 742.76 ± 194.72 ml/min), peak minute ventilation (38.20 ± 13.07 vs 45.33 ± 12.31 L), peak oxygen uptake/heart rate (5.11 ± 1.47 vs 9.43 ± 2.79 ml/b) and peak end-tidal partial pressure of CO₂ (23.73 ± 5.39 vs 35.30 ± 5.45 mm Hg) during exercise.

Conclusions

Compared to IDCM, patients with IPAH had worse pulmonary function and exercise capacity resulting from severe ventilation/perfusion mismatching and gas exchange abnormalities.