Exercise ventilatory inefficiency may be a specific feature of patients with acromegaly

Purpose: Reduction in exercise capacity and peak oxygen uptake (V̇O2) are common in acromegaly, but ventilatory alterations during exercise remain unstudied. We evaluated the exercise ventilatory response in terms of efficiency in patients with acromegaly. Methods: We prospectively evaluated 10 patients with acromegaly in a phase of disease control. To minimise confounders related to ventilatory response and anthropometric differences, acromegalic patients were matched with 10 control subjects according to age, body mass index, and body surface area. Chronic diseases, any cardio-respiratory condition likely to alter ventilatory response, and evidence of cardiac dysfunction were excluded. Pulmonary function tests and maximal cardiopulmonary exercise testing were performed. Ventilatory response was assessed via minute ventilation (V̇E)/carbon dioxide(CO2) output slope (V̇E/V̇CO2slope) and end-tidal carbon dioxide pressure (PETCO2). Exercise ventilatory inefficiency (EVin) was defined according to reference values for healthy individuals. Results: No alterations in lung function were observed in either group. Compared with controls, patients with acromegaly showed lower power output and V̇O2 at peak (1.38 ± 0.20 vs. 1.90 ± 0.64 L·min-1; p = 0.033). Breathing patterns were similar to those of controls, but acromegalic patients exhibited higher values of V̇E/V̇CO2slope (31.8 ± 3.7 vs. 28.0 ± 2.7; p = 0.018), lower PETCO2 at peak (31.1 ± 5.3 vs. 36.9 ± 3.0 mmHg; p = 0.008), and a greater prevalence of EVin (60% vs. 10%; p = 0.019). No correlations emerged between ventilatory inefficiency and biochemical or clinical variables. Conclusion: Patients with acromegaly display ventilatory inefficiency during exercise. These findings suggest subclinical alveolar-capillary impairment or altered CO2 chemosensitivity. Exercise testing may help unmask these abnormalities, supporting its role in risk stratification and rehabilitation planning.