Introduction: Unexplained exertional dyspnea (UED) is common in non-severe covid survivors(NSCS) implied as deconditioning in most cases. Subclinical heart damage(SCHD), not detected by routine test, may underlie. Post exercise heart rate recovery time (HRRT) may be a marker. We aimed to compare cardiopulmonary exercise test (CPET) indices in 2 groups(Gp) of NSCS with deconditioning and different HRRT. Methods: In a cross sectional study, NSCS with UED underwent(CPET) 6 months after disease. Cardiopulmonary assays including chest image, pulmonary function test and echocardiography were normal. Patients with CPET diagnosis of deconditioning were selected. Upon HRRT, they were categorized into 2 Gp; normal(>20/min) and abnormal. VO2, AT, VE/VCO2, O2 pulse, were compared between 2 Gp. Results: 25 deconditioned NSCS were enrolled (11 patients in Gp1 with abnormal HHRT?20 ,14 in Gp2 with HRRT >20 ). Mean HRRT was significantly greater than Gp1. Mean Vo2,AT, o2 pulse , ? Vo2/WR were non-significantly greater in Gp2;while, Vd/Vt in rest and max load were greater in Gp1(details in table1).
| index | Gp1 | Gp2 | P |
| Age | 49.45±12.21 | 44.43±9.70 | 0.28 |
| HRRT | 17.36±2.20 | 27.21±4.44 | 0.00 |
| VO2Max | 78.72±9.99 | 81.85±6.11 | 0.37 |
| AT | 56.14±14.64 | 59.45±16.36 | 0.60 |
| O2 pulse | 76.45±8.26 | 82.57±9.71 | 0.10 |
| ?VO2/?WR | 10.13±2.60 | 12.58±3.65 | 0.06 |
| Vd/Vt rest | 0.30±0.04 | 0.26±0.07 | 0.11 |
| Vd/Vt max | 0.23±0.06 | 0.19±0.06 | 0.14 |
| PETCO2AT | 35.60±4.86 | 36.80±5.00 | 0.55 |
Conclusion: On a small group of patients, our study supports the hypothesis that HRRT may indicate SCHD in NSCS; further studies with long term follow up and larger groups are needed.