Materials and Methods
Present study is a cross-sectional case-control study performed in a single academic center. Patients aged between 20 and 60 years that were diagnosed with COVID-19 infection and hospitalized with this diagnosis were included. Patients that were past or current smokers, those with known coronary artery disease or diabetes, those with a history of heart failure due to any cause and patients on any kind of vasoactive drugs that might affect CFVR measurements were excluded. In addition, patients with a suboptimal image quality on echocardiography or patients with a condition that precluded administration of adenosine (such as asthma) were excluded. 50 COVID-19 patients were initially screened but 11 patients were excluded after applying these criteria. 40 age and gender matched subjects without a previous history of COVID-19, no active symptoms and had a negative nasopharyngeal swab for COVID-19 were enrolled as controls. Demographic, clinical and laboratory parameters were recorded with direct interviews and with using institutional electronic medical database.
The study was conducted according to the 1975 Helsinki and its subsequent revisions. All patients gave their informed consent, and the study was approved by a local ethics committee.