Ventilatory inefficiency in major depressive disorder: a potential adjunct for cardiac risk stratification in depressive disorders?

BACKGROUND: Cardiopulmonary exercise testing (CPET) provides insights into ventilatory, cardiac and metabolic dysfunction in heart and lung diseases and might play a role in cardiac risk stratification in major depressive disorder (MDD).

OBJECTIVE: The VE/VCO(2)-slope indicates ventilatory efficiency and has been applied to stratify the cardiac risk in heart failure (HF). Therefore, the current study was conducted to evaluate and classify ventilatory efficiency and its relationship to physical fitness and disease severity in MDD.

METHODS: Exhaustive incremental exercise testing was completed by 15 female MDD patients and pair matched controls. The ventilatory threshold (VT) and the VE/VCO(2)-slope were assessed. Statistical analyses were conducted by means of MANOVAs and follow-up univariate ANOVAs.

RESULTS: In patients with MDD, significant different relative work rates and oxygen uptakes at the VT in comparison to healthy controls were observed. Furthermore, we found an increased VE/VCO(2)-slope in depressed patients. We additionally report an inverse relationship between the VE/VCO(2)-slope and peak power output as well as peak oxygen uptake solely in patients. We did not observe any association of assessed parameters with disease severity.

CONCLUSION: CPET measures indicate ventilatory inefficiency in patients with MDD. The elevated VE/VCO(2)-slope indicates that patients with MDD need to ventilate significantly more to a given amount of developing CO(2). Further investigations are needed to verify the application of the ventilatory classification system to stratify cardiovascular risk in depressive disorder.