Cardiac injury has been recognized as a severe complication of COVID-19 infection and associated with significantly increased mortality in hospitalized patients (1). Cardiac magnetic resonance (MR) has been recommended by the American College of Cardiology and the European Society of Cardiology for COVID-19 patients with suspected myocardial injury (2-4). A few recently published studies found cardiac structure and function abnormalities in patients recovered from asymptomatic or mild COVID-19, or without cardiac symptoms (5-7). However, most cardiac MR values are associated with multiple factors and have a large reference ranges for healthy individuals (8), implying substantial individual differences will exist. Studies targeting the comparison of cardiac MR results before and after COVID-19 infection have been advised (9). This study aimed to evaluate the prevalence of cardiac involvement in mild, non-hospitalized, recovered COVID-19 patients and investigate the changes of cardiac structure and function by comparing multiparametrical cardiac MR before and after recent COVID-19 breakthrough infections in China.
MethodsAll volunteers have no history of COVID-19 infection demonstrated by polymerase chain reaction (PCR) tests 2-4 times each month from 2021 to 2022. 39 volunteers mentioned above who infected with COVID-19 confirmed by PCR or antigen detection in December 2022 were willing to participate repeated cardiac MR examination. Inclusion criteria were: no history of COVID-19 infection, COVID-19 infection confirmed by PCR or antigen detection before the second cardiac MR examination. Exclusion criteria were: contraindications to cardiac MR, image data loss of the first cardiac MR examination, inadequate image quality of cardiac MR examinations for cardiac MR analysis owing to artifacts.This study was approved by the institutional review board of our hospital and written informed consent was obtained from all the participants.All participants underwent baseline and follow-up cardiac MR examinations on the same 3-Tesla scanner (GE Healthcare) . The cardiac MR scanning protocols consisted of: 1) 2-chamber, 3-chamber, 4-chamber and short-axis cine imaging 2) black blood T2-weight imaging 3) native T1 and T2 mapping 4) post-contrast T1 mapping 5) late gadolinium enhancement (LGE) imaging. LGE imaging was performed 10-15 mins after intravenous administration of gadolinium-based contrast agent (Beilu Pharmaceutical, Beijing, China) using a myocardial delayed enhancement sequence in long-axis and short-axis views. All cardiac MR images were analyzed with CVI 42 software (Canada) by an experienced cardiovascular radiologist with 12 years of experience in cardiac MR was blinded to the participants’ clinical manifestation and laboratory profiles. Myocardial edema was assessed by calculated the ratio between myocardial signal intensity (SI) to skeletal muscle SI. Left ventricle (LV) and right ventricle (RV) functional parameters were automatically calculated after drawing endocardial and epicardial contours. In the end-diastolic frame, automatically tracked throughout the cardiac cycle to obtain biventricular strain parameters, including global radial peak strain (GRS), global circumferential peak strain (GCS), and global longitudinal strain (GLS). Statistical analysis were performed using SPSS version 23.0 (SPSS Inc. USA). Continuous variables were reported as means and standard deviations when they were normally distributed and expressed as medians and interquartile ranges when they were non-normally distributed. Paired group comparisons were performed using the paired samples t-test or the Wilcoxon Signed Rank test for parametric and non-parametric data, respectively. T-test and Mann-Whitney U test were used to compare the means with normal distribution and non-normal distribution, respectively. P<0.05 was regarded as the level for statistical significance.ResultsPatients’ characteristics and blood test results are shown in Table 1. The comparisons of cardiac MR results between before and after COVID-19 infection are presented in Table 2. All the cardiac MR parameters including cardiac structure, function, native T1, native T2 and ECV were not significantly different between before and after COVID-19 infection (Figure 1). LGE was minimally detectable in 4 participants in both pre- and post-COVID-19 infection cardiac MR scans with the same location and pattern. The cardiac MR results after COVID-19 infection between symptomatic group and asymptomatic group (Table 3). DiscussionTo This intra-individual cardiac MR comparison study demonstrated that in non-hospitalized COVID-19 patients with normal myocardial enzyme, the cardiac structure and function after COVID-19 infection are similar to those before COVID-19 infection, no matter with or without mild symptoms, which indicated no measurable myocardial injury in these patients. This can alleviate wide social concern on COVID-19 infection related myocarditis. More importantly, it is relevant to diagnose COVID-19 infection related myocardial injury by combining multiple cardiac MR parameters and clinical measures and compare with historical cardiac MR images, which may reduce misdiagnosis.ConclusionIn conclusion, our intra-individual comparison multipara metric cardiac MR study demonstrated that mild non-hospitalized COVID-19 participants had no measurable cardiac structure and function abnormalities on cardiac MR.

Acknowledgements

No