Brown JT; Saigal A; Karia N; Patel RK; Razvi Y; Constantinou N; Steeden
JA; Mandal S; Kotecha T; Fontana M; Goldring J; Muthurangu V; Knight DS

Journal of the American Heart Association. 11(9):e024207, 2022 May 03.

Background Ongoing exercise intolerance of unclear cause following
COVID-19 infection is well recognized but poorly understood. We
investigated exercise capacity in patients previously hospitalized with
COVID-19 with and without self-reported exercise intolerance using
magnetic resonance-augmented cardiopulmonary exercise testing.
Methods and Results Sixty subjects were enrolled in this single-center prospective
observational case-control study, split into 3 equally sized groups: 2
groups of age-, sex-, and comorbidity-matched previously hospitalized
patients following COVID-19 without clearly identifiable postviral
complications and with either self-reported reduced (COVIDreduced) or
fully recovered (COVIDnormal) exercise capacity; a group of age- and
sex-matched healthy controls. The COVID reduced group had the lowest peak
workload (79W [Interquartile range (IQR), 65-100] versus controls 104W
[IQR, 86-148]; P=0.01) and shortest exercise duration (13.3+/-2.8 minutes
versus controls 16.6+/-3.5 minutes; P=0.008), with no differences in these
parameters between COVIDnormal patients and controls. The COVIDreduced
group had: (1) the lowest peak indexed oxygen uptake (14.9 mL/minper kg
[IQR, 13.1-16.2]) versus controls (22.3 mL/min per kg [IQR, 16.9-27.6];
P=0.003) and COVIDnormal patients (19.1 mL/min per kg [IQR, 15.4-23.7];
P=0.04); (2) the lowest peak indexed cardiac output (4.7+/-1.2 L/min per
m2) versus controls (6.0+/-1.2 L/min per m2; P=0.004) and COVIDnormal
patients (5.7+/-1.5 L/min per m2; P=0.02), associated with lower indexed
stroke volume (SVi:COVIDreduced 39+/-10 mL/min per m2 versus COVIDnormal
43+/-7 mL/min per m2 versus controls 48+/-10 mL/min per m2; P=0.02). There
were no differences in peak tissue oxygen extraction or biventricular
ejection fractions between groups. There were no associations between
COVID-19 illness severity and peak magnetic resonance-augmented
cardiopulmonary exercise testing metrics. Peak indexed oxygen uptake,
indexed cardiac output, and indexed stroke volume all correlated with
duration from discharge to magnetic resonance-augmented cardiopulmonary
exercise testing (P<0.05).
Conclusions Magnetic resonance-augmented
cardiopulmonary exercise testing suggests failure to augment stroke volume
as a potential mechanism of exercise intolerance in previously
hospitalized patients with COVID-19. This is unrelated to disease severity
and, reassuringly, improves with time from acute illness.