Assessment of functional capacity with cardiopulmonary exercise testing in non-severe COVID-19 patients at three months follow-up

Introduction

Long-term effects of Coronavirus Disease of 2019 (COVID-19) and their sustainability in a large number of patients are of the utmost relevance. We aimed to determine: 1)functional capacity of non-severe COVID-19 survivors by cardiopulmonary exercise testing (CPET); 2)those characteristics associated with worse CPET performance.

Methods

We prospectively enrolled the first 150 consecutive subjects with laboratory-confirmed COVID-19 infection discharged alive from March to April 2020 at Azienda Sanitaria Locale (ASL)3, Genoa, Italy. At 3-month from hospital discharge, complete clinical evaluation, trans-thoracic echocardiography, cardiopulmonary exercise testing (CPET), pulmonary function test (PFT), and dominant leg extension (DLE) maximal strength evaluation were performed.

Results

Excluding severe and incomplete/missing cases, 110 patients were analyzed. Median percent predicted peak oxygen uptake (%pVO2) was 90.9(79.2-109.0)%. Thirty-eight(34.5%) patients had %pVO2 below, whereas 72(65.5%) above the 85% predicted value (indicating normality). Median PFT parameters were within normal limits.

Eight(21.1%) patients had a mainly respiratory, 9(23.7%) a mainly cardiac, 3(7.9%) a mixed-cardiopulmonary, and 18(47.4%) a non-cardiopulmonary limitation of exercise. Eighty-one(73.6%) patients experimented at least one symptom, without relationship with %pVO2 (p>0.05).

Multivariate linear regression analysis showed age (β=0.46, p=0.020), percent weight loss (β=-0.77, p=0.029), active smoke status (β=-7.07, p=0.019), length of hospital stay (β=-0.20, p=0.042), and DLE maximal strength (β=1.65, p=0.039) independently associated with %pVO2.

Conclusions

Half of non-severe COVID-19 survivors show functional capacity limitation mainly explained by muscular impairment, albeit cardiopulmonary causes are possible. These findings call for future research to identify patients at higher risk of long-term effects, that may benefit from careful surveillance and targeted rehabilitation.

Take-home messages

at 3-month cardiopulmonary exercise testing 38/110(34.5%) non-severe COVID-19 survivors had percent predicted peak oxygen uptake (%pVO2) < 85% (indicating normality). Half of them had functional capacity limitation mainly explained by muscular impairment.