Aim. To assess the structural and functional myocardial characteristics in patients with unstable angina (UA) and post-COVID-19 syndrome (PACS), stratified by smoking status.

Materials and methods. The study included 147 patients with UA aged 35–76 years. Participants were divided into a PACS cohort (Group I, n = 88) and a non-PACS cohort (Group II, n = 59). Each group was further subdivided into smokers (subgroups IA and IIA) and non-smokers (subgroups IB and IIB). All patients underwent transthoracic echocardiography to evaluate standard structural and functional cardiac parameters. N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels were also quantified. Statistical analysis was performed using parametric and non-parametric tests, correlation analysis, and regression modeling.

Results. Patients with PACS demonstrated more pronounced cardiac remodeling compared to the non-PACS group, indicated by a lower left ventricular ejection fraction (LVEF) (50.48 ± 9.11 % (I) vs 53.15 ± 9.14 % (II), p < 0.05) and larger left atrial (LA) dimensions (4.09 ± 0.42 cm (I) vs 3.93 ± 0.48 cm (II), p < 0.05). The most unfavorable changes were observed in smokers with PACS, who exhibited the lowest LVEF values, higher left ventricular mass index, and elevated NT-proBNP levels. NT-proBNP concentration was significantly higher in the PACS group compared to patients without PACS (621.8 (370.0; 1500.0) ng/mL (I) vs 254.9 (92.0; 394.0) ng/mL (II), p < 0.005). Pathological patterns of left ventricular geometry, particularly eccentric hypertrophy, were more common among PACS patients, especially in smokers. Statistically significant correlations were found between smoking intensity, NT-proBNP levels, myocardial remodeling parameters, and hematological inflammatory markers. Linear regression analysis revealed a significant positive correlation between smoking intensity and elevated NT-proBNP levels.

Conclusions. Post-COVID-19 syndrome in patients with unstable angina is associated with moderate but significant cardiac structural and functional deterioration. Smoking substantially aggravates these changes, as evidenced by markedly elevated NT-proBNP levels and more pronounced echocardiographic signs of pathological myocardial remodeling.