Baseline characteristics of the included patients
| Demographic and clinical variables at admission | ||
| Age, years | 54 (43–55) | |
| Women, % | 62.5 | |
| Length of stay, days | 12 (6–16) | |
| Abnormal X-rays or CT, n (%) | 8 (100) | |
| Received steroids, n (%) | 8 (100) | |
| Received antibiotics, n (%) | 8 (100) | |
| Received oxygen therapy, n (%) | 8 (100) | |
| Received remdesivir, n (%) | 6 (75) | |
| Received tocilizumab, n (%) | 4 (50) | |
| Required intubation, n (%) | 1 (12.5) | |
| Clinical, echocardiographic, laboratory and pulmonary parameters | ||
| Time to tests after discharge, days | 336 (315–394) | |
| BMI, kg/m2 | 29 (26.5–30.5) | |
| FEV1, % | 61.2±4 | |
| Structural heart disease, n (%) | 0 (0) | |
| Valvular heart disease, n (%) | 0 (0) | |
| DLCO, % | 65.5 (62.5–68.5) | |
| Haemoglobin,g/L | 138 (138–150) | |
| NT-pro-BNP, pg/mL | 25.5 (15–35) | |
| CRP, mg/L | 3.2 (1.1–6.5) | |
| CPET Variables | Rest | Peak exercise |
| Workload, W | 95.5 (83–124) | |
| Exercise time, min | 9 (8.4–12) | |
| HR, bpm | 76±12.9 | 146±16.7 |
| Chronotropic index* | 0,76±0.17 | |
| SBP, mm Hg | 118.1±9.2 | 155.8±20.2 |
| RR, breaths/min | 16±3.3 | 28±5.5 |
| Breathing reserve >30%, n (%) | 8 (100) | |
| VE, L/min | 11.5 (10–13) | 45.5 (42–73) |
| O2 desaturation during CPET, n (%) | 8 (100) | |
| RER | 1.13±0.34 | |
| Reached VT, n (%) | 8 (100) | |
| PeakVO2, mL/kg/min | 17.2±3.8 | |
| PeakVO2%, % | 74.2±12.2 | |
| VO2AT, mL/kg/min | 10.6±2.4 | |
| PetCO2, mmHg | 33.5 (30.5–35.5) | 38.6 (36.5–40.5) |
| VO2 pulse, mL/beat | 10.1 (8.4–10.4) | |
| VE/VCO2 slope | 31.2±5.3 | |
| OUES, mL/min | 1670 (1290–1995) | |
| Predicted OUES | 2219 (1920–2637) | |
| Mild reduction of peakVO2% (80%–90%), n (%) | 3 (37.5) | |
| Moderate reduction of peakVO2% (60-<80%), n (%) | 5 (62.5) | |
| Abnormal flow-volume curve at spirometry, n (%) | 0 (0) | |
| CPET Limiting symptoms | ||
| Muscular fatigue | 5 | |
| Dyspnoea | 2 | |
| Muscular fatigue and dyspnoea | 1 | |
| Chest pain | 0 | |
| Dizziness | 0 | |
| Arrhythmias | 0 | |
Continuous variables are expressed as means (±1 SD) or medians (IQR), and discrete variables as frequencies and percentages.
*Chronotropic index= [HRpeak exercise – HRrest)] / [(220 – age – HRrest)]).
BMI, body mass index; CPET, cardiopulmonary exercise testing; CRP, C reactive protein; DLCO, diffusing capacity of lungs for carbon monoxide; FEV1, forced expiratory volume 1 s; HR, heart rate; NT-pro-BNP, N-terminal pro-B-type natriuretic peptide; OUES, oxygen uptake efficiency slope; PeakVO2, peak oxygen uptake; PeakVO2%, percent of predicted peak oxygen uptake; PetCO2, end-tidal CO2; RER, respiratory exchange ratio; RR, respiratory rate; SBP, systolic blood pressure; VE, minute ventilation; VE/VCO2 slope, ventilatory efficiency; VO2AT, oxygen consumption at anaerobic threshold; VT, ventilatory threshold.