Patients hospitalized with COVID-19 and high cardiac troponin levels had more ventricular impairment and myocardial scarring in the early stages of recovery compared with patients without the virus, according to a study published in Circulation. However, the number of cases of myocarditis was low and the cause of the scarring was varied, including a newly identified pattern of microinfarction.

The multicenter observational study conducted by Jessica Artico, MD, et. al., across 25 hospitals in the U.K., enrolled 342 patients with COVID-19 and elevated troponin levels between June 2020 and March 2021. All had an MRI within 28 days of discharge. The investigators recruited two prospective control groups: 64 patients with COVID-19 and normal troponin levels and 113 patients without COVID-19 or elevated troponin level matched by age and cardiovascular comorbidities. Most of the patients were men (69%) and the median age was 61 years.

The results showed a twofold greater frequency of any cardiac abnormality, defined as left or right ventricular impairment, scar or pericardial disease, among patients with COVID-19 vs. controls (61% vs. 36%); the rate was 31% in those without COVID-19 or elevated troponin.

Ventricular impairment was significantly more common in patients with COVID-19 compared with controls (17.2% vs. 3.1% and 7.1%), as was scarring (42% vs. 7% and 23%). Cases had a higher occurrence of infarction (13%) or microinfarction (9%) than controls (2% and 0%, and 1% and 0%, respectively; p<0.01 and p<0.001), but no difference was found in nonischemic scar (13% vs. 5% and 14%; p=0.10). The prevalence of probable recent myocarditis was 6.7% (23/342) in cases compared with 1.7% (2/113) in non-COVID controls (p=0.045).

During follow-up, four patients died and 34 experienced a major adverse cardiovascular event (MACE) (10.2%), which was similar with controls (6.1%; p=0.70). Myocardial scar was an independent predictor of MACE (odds ratio, 2.25; 95% CI, 1.12-4.57; p=0.02), but previous COVID-19 infection and troponin were not.

The authors note that “The working clinical diagnosis for myocardial injury was diverse and difficult to ascertain in many cases,” highlighting the challenge of defining the mechanism of myocardial injury in COVID-19 without MRI. Additionally, they write, “Excess scar was typically that of myocardial infarction or microinfarction, the latter being a newly described imaging pattern, with myocardial inflammation and probable recent myocarditis occurring less frequently.” Future work is needed to determine the prognostic, functional and quality of life effects of these changes in the longer term.

Clinical Topics: COVID-19 Hub, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Magnetic Resonance Imaging

Keywords: Inflammation, Magnetic Resonance Imaging, Heart Diseases, Myocardial Infarction, COVID-19, Follow-Up Studies, Prospective Studies, Quality of Life, Odds Ratio, Prevalence, Patient Discharge, Prognosis, Cicatrix, Myocarditis, Troponin, Female, Middle Aged, Male

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