Abstract
Background and aims: Myocardial injury is frequent in patients hospitalized with Sars-COV-2 infection and portents a worse prognosis, but the cause of myocardial injury is uncertain. Coronary microvascular dysfunction (CMD) has been hypothesized as a possible explanation, but direct evidence demonstrating CMD in COVID-19 patients is missing. In the present study, we aimed to investigate whether CMD is present in hospitalized COVID-19 patients, and to understand whether there is a relationship between biomarkers of myocardial injury, myocardial strain and inflammation and CMD in COVID-19 patients. Methods: 39 patients that were hospitalized with COVID-19 and 40 control subjects were included to the present study. Biomarkers for myocardial injury, myocardial strain, inflammation and fibrin turnover were obtained at admission. A comprehensive echocardiographic examination, including measurement of coronary flow velocity reserve (CFVR), were done after the patient was stabilized. Results: Patients with COVID-19 infection had a lower hyperemic coronary flow velocity, resulting in a significantly lower CFVR (2.0±0.3 vs. 2.4±0.5, p<0.001). Patients with severe COVID-19 also had a lower CFVR compared to those with moderate COVID-19 (1.8±0.2 vs. 2.2±0.2, p<0.001) due to an increase in basal flow velocity (30.0±6.2 vs. 26.0±4.8, p=0.04). CFVR correlated with troponin (p=0.003,r:-0.470), B-type natriuretic peptide (p<0.001,r:-0.580), C-reactive protein (p<0.001,r:-0.369), interleukin-6 (p<0.001,r:-0.597) and d-dimer (p<0.001,r:-0.561), with the three latter biomarkers having the highest area-under-curve for predicting CMD. Conclusions: CMD is common in patients with COVID-19, and is related with the severity of the infection. CMD may also explain the “cryptic” myocardial injury seen in patients with severe COVID-19 infection.