The study included 190 patients presenting with unstable angina (UA) and confirmed normal coronary arteries via invasive angiography. Participants were divided into two age- and sex-matched groups: 95 patients with a history of COVID-19 [COVID (+) UA-NCA] and 95 patients without a prior history of the infection [COVID (–) UA-NCA]. In the study group, COVID-19 was confirmed via RT-PCR and computed tomography. All participants underwent coronary angiography to perform Thrombolysis in Myocardial Infarction (TIMI) frame count (TFC) measurements. CSF was diagnosed in patients with a corrected TFC (CTFC) ≥ 27.

Results: 

CSF prevalence was significantly higher in the COVID (+) UA-NCA group than in the COVID (–) UA-NCA group (18.9% vs. 5.3%, p = 0.003). Individual CTFC values for the LAD, 

Conclusions: 

CSF prevalence is significantly higher in patients with a history of COVID-19, suggesting persistent microvascular impairment.