Importance of Cardiopulmonary Exercise Testing amongst Subjects Recovering from COVID-19.

The cardiopulmonary exercise test (CPET) provides an objective assessment of ventilatory limitation, related to the exercise minute ventilation (V) coupled to carbon dioxide output (V) (V/V); high values of V/V define an exercise ventilatory inefficiency (EV). In subjects recovered from hospitalised COVID-19, we explored the methodology of CPET in order to evaluate the presence of cardiopulmonary alterations. Our prospective study (RESPICOVID) has been proposed to evaluate pulmonary damage's clinical impact in post-COVID subjects. In a subgroup of subjects (RESPICOVID2) without baseline confounders, we performed the CPET. According to the V/V, subjects were divided into having EV and exercise ventilatory efficiency (EV). Data concerning general variables, hospitalisation, lung function, and gas-analysis were also collected. The RESPICOVID2 enrolled 28 subjects, of whom 8 (29%) had EV. As compared to subjects with EV, subjects with EV showed a reduction in heart rate (HR) recovery. V/V was inversely correlated with HR recovery; this correlation was confirmed in a subgroup of older, non-smoking male subjects, regardless of the presence of arterial hypertension. More than one-fourth of subjects recovered from hospitalised COVID-19 have EV. The relationship between EV and HR recovery may represent a novel hallmark of post-COVID cardiopulmonary alterations.