The role of microvascular dysfunction in the pathogenesis of heart failure with preserved ­efficiency fraction

Background. The results of a growing number of international studies support the assumption that the prevalence of coronary microvascular dysfunction is much higher than previously thought, including in patients with heart failure with preserved ejection fraction. Aim. To study the role of coronary microvascular dysfunction in the pathogenesis of heart failure with preserved ejection fraction in patients with non-obstructive lesions of the coronary arteries. Material and methods. The study included 73 patients with non-obstructive lesions of the coronary arteries. Dynamic single-photon emission computed tomography was used to evaluate the parameters of coronary blood flow reserve. Coronary microvascular dysfunction was defined as the presence of reduced coronary blood flow reserve 2. The distribution of patients was carried out depending on the reserve of coronary blood flow: the first group (n=35) included patients with a reduced reserve 2, the second group with preserved reserve 2 (n=38). Statistical processing of the study results was carried out using nonparametric methods: in the analysis of quantitative indicators, the MannWhitney test was used; in the analysis of qualitative features, the analysis of contingency tables using the Pearson 2 test was performed. To search for relationships between variables, correlation analysis with the calculation of Spearman's correlation coefficients was used. Results. In 82.9% of cases, patients in the first group had heart failure, while in patients in the second group, it was diagnosed only in 44.7% of cases (p=0.014). The values of the coronary blood flow reserve correlated with the size of the left atrium (r=0.527; p=0.001), the E/A (r=0.321, p=0.012) and E/e' ratio (r=0.307; p=0.021). In patients with heart failure, the levels of coronary blood flow reserve correlated with the functional class: in patients with functional class I (n=21), the values of this indicator were 2.87 (2.52; 2.94), with class II (n=8) 1.98 (1.65; 2.16), with functional class III (n=17) 1.51 (1.23; 1.69). Conclusion. The presence of coronary microvascular dysfunction is associated with a higher incidence of heart failure with preserved ejection fraction; values of coronary blood flow reserve correlate with parameters of diastolic dysfunction.