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. 2023 May 19. Online ahead of print. doi: 10.1016/j.pcad.2023.05.005

Table 3.

Comparison abnormal exercise test responses in long COVID and dyspnea control subjects.

Long COVID
Control
N = 77 N = 766 P
Cardiac Responses
Resting HR ≥ 100 4 (5.2) 45 (5.9) 0.41a, b
Chronotropic incompetence 34 (44) 261 (34) 0.05a, b, c
Abnormal HR recovery 16 (21) 157 (20) 0.81a, b, c
Low Peak SBP 16 (21) 100 (13) 0.046a, b, c
Exercise ST-T abnormalities 4 (5.2) 33 (4.3) 0.78a, b, c
PVC Frequency 0.38
 None 47 (61) 410 (54)
 < 5/min 19 (25) 263 (34)
 ≥ 5/min or pairs 9 (12) 80 (10)
 VT 2 (2.6) 13 (1.7)
Symptoms of chest pain 11 (14) 108 (14) 0.51
Pulmonary Responses
Submaximal effort 14 (18) 134 (18) 0.88
Low breathing reserve <15% 2 (2.6) 17 (2.2) 0.49a, b, c
Low O2 saturation < 93% 3 (3.9) 29 (3.8) 0.84a, b, c
E/V̇CO2 nadir 28 ± 5 29 ± 4 0.32a, b, c
High V̇E/V̇CO2 11 (14) 107 (14) 0.80a, b, c
Symptoms of dyspnea 44 (57) 501 (66) 0.09

Values are mean ± SD or n (%).

Abbreviations: HR = heart rate; SBP = systolic blood pressure.

Chronotropic incompetence = HR reserve <80% predicted for age and sex; Abnormal HR recovery = HR Recovery <13 bpm if active recovery or < 18 bpm if no active recovery; Low peak SBP = peak SBP < 10th percentile for age and sex; Submaximal effort = peak respiratory exchange ratio < 1.0; Low O2 saturation = minimum O2 saturation < 93%; V̇E/V̇CO2 nadir = lowest ratio of V̇E to V̇CO2 during exercise; High V̇E/V̇CO2 = V̇E/V̇CO2 nadir >2 standard deviations from mean for age and sex.

a

Adjusted for age and sex.

b

Adjusted for beta blocker use.

c

Adjusted for effort based on RER.