Background: Cardiorespiratory complications are commonly reported among patients with long COVID-19 syndrome. However, their effect on exercise capacity remains inconclusive.

Aim: To investigate the impact of long COVID-19 on exercise tolerance combining cardiopulmonary exercise testing (CPET) and echocardiography data.

Methods:42 patients (mean±SD 54.5±12.5yrs) underwent a CPET and echocardiography 149±92 days from hospital discharge. CPET was performed on a cycle ergometer using an incremental protocol to the limit of tolerance. Echocardiography calculated left ventricular ejection fraction (LVEF) according to Simpson?s method. The ratio (e/e?) of early trans-mitral flow velocity (E) to early mitral annular velocity (Em) was estimated as a surrogate of left ventricular end diastolic filling pressures. Tricuspid annular systolic velocity (SRV) was used to evaluate the right ventricular systolic performance. Through tricuspid regurgitation velocity and inferior vena cava diameter, end-respiratory variation systolic pulmonary artery pressure (PASP) was calculated.

Results: There was a negative association of E/e? with peak work rate (WRpeak) (r=-0.333, p=0.031) and peak oxygen consumption (VO2peak) (r=-0.336, p=0.032), but there was no correlation with oxygen pulse (O2pulse). SRV was associated with WRpeak (r=0.447, p=0.003), VO2peak (r=0.556, p=0.001) and O2pulse (r=0.330, p=0.040). PASP was negatively associated with VO2peak (r=-0.319, p=0.042).

Conclusions: In patients with long COVID-19 syndrome, exercise capacity is inversely associated with left ventricular diastolic performance, left ventricular end-diastolic pressure, PASP and SRV.