Post COVID-19 syndrome with impairment of flow-mediated epicardial vasodilation and flow reserve

Aims: The aim of this study is to evaluate whether post-acute sequelae of COVID-19 cardiovascular syndrome (PASC-CVS) is associated with alterations in coronary circulatory function. Materials and Methods: In individuals with PASC-CVS but without known cardiovascular risk factors (n = 23) and in healthy controls (CON, n = 23), myocardial blood flow (MBF) was assessed with ¹³N-ammonia and PET/CT in mL/g/min during regadenoson-stimulated hyperemia, at rest, and the global myocardial flow reserve (MFR) was calculated. MBF was also measured in the mid and mid-distal myocardium of the left ventricle (LV). The Δ longitudinal MBF gradient (hyperemia minus rest) as a reflection of an impairment of flow-mediated epicardial vasodilation, was calculated. Results: Resting MBF was significantly higher in PASC-CVS than in CON (1.29 ± 0.27 vs. 1.08 ± 0.20 ml/g/min, p ≤.024), while hyperemic MBFs did not differ significantly among groups (2.46 ± 0.53 and 2.40 ± 0.34 ml/g/min, p =.621). The MFR was significantly less in PASC-CVS than in CON (1.97 ± 0.54 vs. 2.27 ± 0.43, p ≤.031). In addition, there was a Δ longitudinal MBF gradient in PASC-CVS, not observed in CON (−0.17 ± 0.18 vs. 0.04 ± 0.11 ml/g/min, p <.0001). Conclusions: Post-acute sequelae of COVID-19 cardiovascular syndrome may be associated with an impairment of flow-mediated epicardial vasodilation, while reductions in coronary vasodilator capacity appear predominantly related to increases in resting flow in women deserving further investigations.