Muller PT; Utida KAM; Augusto TRL; Spreafico MVP; Mustafa RC; Xavier AW; Saraiva EF;

Respiratory Medicine [Respir Med] 2018 Dec; Vol. 145, pp. 101-109. Date of Electronic Publication: 2018 Oct 30.

Background: Left ventricular diastolic dysfunction (LVDD) is highly prevalent in COPD and conflicting results have emerged regarding the consequences on exercise capacity in the 6MWT. We sought to examine the ventilatory efficiency and variability metrics as the primary endpoint and aerobic capacity (V’O2) as the secondary endpoint.
Methods: Forty subjects were included and submitted to comprehensive lung function tests, detailed pulsed-Doppler echocardiography, and cardiopulmonary exercise testing. Four subjects were excluded due to concomitant cardiac disease and two owing to COPD exacerbation.
Results: Seventeen COPD/LVDD+ and seventeen COPD/LVDD-individuals were closely matched for baseline characteristics. Throughout the exercise, there was no difference between-groups for primary (V’E/V’CO2slope and V’E/V’CO2nadir, p > 0.05 for both) or secondary endpoints (V’O2peak%pred, p > 0.05). Ventilatory variability remained unchanged. However, after very well age- and sex-matched subgroup analysis, five-moderate and three-mild COPD/LVDD + subjects with elevated left ventricular filling pressure (E/e’>13, n = 8), presented a downward-shifted V’E/V’CO2slope (25.7 ± 5.1 vs 33.4 ± 7.1, p = 0.031) and V’E/V’CO2nadir reduction (29.7 ± 3.9 vs 36.3 ± 7.2, p = 0.042) besides significantly better V’O2peak%pred (92.1 ± 21.6% vs 75.8 ± 13.1%, p = 0.045) compared to 8 COPD/LVDD-controls. Ventilatory variability remained once again unchanged.
Conclusions: COPD/LVDD overlap is not associated with worse exercise tolerance and/or wasted ventilation in excess compared to controls, even when suspected for elevated left ventricular filling pressure. Further studies are warranted to study specifically if augmented pulmonary blood transit time can allow better gas-exchange, thus preserving exercise capacity under specific conditions in COPD patients without heart failure.