Materials and methods:
This was a prospective single center study in the Department of
Cardiology at a tertiary care center in India. A total of 400
consecutive subjects recently recovered (within 30-45 days) from
COVID-19 infection were screened. All these subjects were COVID-19
positive in the past using reverse transcription-polymerase chain
reaction (RT-PCR) swab test. Patients were considered recovered by the
discharge criteria (normal temperature lasting longer than 3 days,
resolved respiratory symptoms and two consecutive negative RT-PCR test
results separated by at least 24 hours) and were isolated for a minimum
of 14 days. Of the 400 subjects, 140 underwent two-dimensional (2D)
speckle tracking echocardiography (STE) for detection of sub-clinical
left ventricular dysfunction. Impaired global longitudinal strain (GLS)
was reported in 39/140 (27.8%) of them. All COVID-19 recovered subjects
with abnormal GLS were further screened for suitability for CMR.
Subjects with: (1) a history of coronary artery disease, myocarditis,
moderate to severe valvular dysfunction, atrial fibrillation or prior
cardiomyopathy; (2) contradictions to gadolinium contrast; (3) severe
renal insufficiency (creatinine clearance rate < 30
mL/min/1.73 m2; (4) pregnancy ; (5) unable to
breath-hold and cooperate during CMR examination, (6) MRI image quality
was not sufficient for analysis and (7) unwillingness to participate or
provide informed consent were excluded. Post exclusion, 30 subjects were
finally enrolled who underwent CMR at baseline and a follow-up scan six
months later in those with abnormal findings in the initial scan.
Additionally, 20 age and sex-matched healthy controls were enrolled who
underwent CMR. All the control subjects had a normal electrocardiogram
(ECG), echocardiography and had no antecedent history or serological
evidence of prior COVID-19 infection. Baseline clinical and biochemical
parameters including hemogram, liver and kidney function tests as well
as inflammatory markers such as C-reactive protein (CRP), serum
ferritin, interleukin (IL)-6, lactate dehydrogenase (LDH) and D-dimer
were obtained at the time of admission during COVID-19 infection for all
subjects. A written informed consent was obtained from all the subjects
prior to a CMR scan. The study protocol was approved by the
institutional ethics committee.