Relation of exercise intolerance to microvascular dysfunction in COVID-19 recovered patients after six months of recovery

Aims: Our aim was to explore the relation between coronary microvascular function, as assessed with transthoracic echocardiographic Coronary Flow Reserve (CFR) and exercise tolerance in COVID-19 recovered patients after 6 months of recovery. Methods: 79 patients with COVID-19 with a mean age (51±12) were recruited 6 months after recovery. All patients underwent transthoracic echocardiographic evaluation of coronary flow reserve (CFR). Furthermore, they underwent self-limited exercise tolerance test (ETT). Results: Based on the metabolic equivalents (METS), participates were stratified to a group with exercise intolerance with METs ≤8 and another group with good exercise tolerance with METs >8. Patients with exercise intolerance had significantly lower CFR (1.8 ± 0.3 vs. 3.1 ± 0.5; P <0.001), Patients with reduced exercise tolerance (METs ≤8) had higher E/e' ratio and left atrial volume index when, compared to subject with METs ≤8 (p< 0.01). Furthermore, brain natriuretic peptide, troponin-I, hs-C reactive protein, lactic dehydrogenase during the acuteness period were considerably elevated in recovered patients with METs <8. Moreover, CFR had significant inverse correlations with E/e' (r = −0.45; P < 0.001). At multivariate analysis CFR appeared to be a sponge independent predictor of reduced exercise tolerance (METs<8) in COVID-19 recovered patients (p<0.001) Conclusions: The current research revealed a significant association between coronary microvascular dysfunction and reduced exercise tolerance and diastolic dysfunction in patients with COVID-19 six months after recovery. Fore that reason, we suggested that microvascular dysfunction is a possible mechanism of exercise intolerance after COVID-19 recovery.