Prognostic value of myocardial flow reserve in patients with heart failure with preserved ejection fraction

Aim. To study the prognostic value of myocardial blood flow (MBF) and myocardial flow reserve (MFR) parameters in patients with heart failure with preserved ejection fraction (HFpEF) and non-obstructive coronary artery disease (CAD) in risk stratification of HFpEF progression during a 12-month follow-up. Materials and methods. The study included 58 patients with non-obstructive CAD and HFpEF (LVEF 62 [58; 66]%). Dynamic CZT-SRECT was used to evaluate MFR and MBF at rest (rest-MBF) and stress (stress-MBF). NT-proBNP levels were determined by the enzyme immunoassay. Diastolic dysfunction parameters were measured using 2D transthoracic echocardiography. Left ventricular systolic global longitudinal strain (GLS) was assessed using 2D speckle tracking. Results. After a 12-month follow-up, the patients were retrospectively divided into 2 groups: group 1 (n = 11) included patients with an unfavorable course of HFpEF, group 2 (n = 47) encompassed patients with a favorable course of the disease. In group 1, the level of NT-proBNP was 3.8 times higher than in group 2 (284.5 [183.42; 716.73] and 1,071.4 [272.4; 2,168.1] pg / ml, respectively). MFR values in group 1 were lower by 45.4% (p < 0.001) than in group 2 (1.19 [0.86; 1.55] vs. 2.18 [1.7; 2.55], respectively). In group 1, rest-MBF levels were higher by 23.6% (p = 0.046) and stress-MBF was lower by 28.2% (p = 0.046) than in group 2. The multivariate regression analysis revealed that NT-proBNP levels (odds ratio (OR) 3.23; p = 0.008), GLS (OR 2.27; p = 0.012), and MFR (OR 8.09; p < 0.001) were independent predictors of adverse outcomes in HFpEF. Based on the ROC analysis, MFR levels = 1.62 (AUC = 0.827; p < 0.001), GLS =-18 (AUC = 0.756; p = 0.002), and NT-proBNP = 760.5 pg / ml (AUC = 0.708; p = 0.040) may be considered as markers of adverse outcomes. However, the combined determination of NT-proBNP and MFR had a greater significance (AUC 0.935; p < 0.001) in risk stratification compared with the monomarker model, while the addition of GLS did not increase the significance of the analysis. Conclusion. Levels of NT-proBNP, GLS, and MFR may be used as non-invasive markers of an adverse course of HFpEF in patients with non-obstructive CAD, while the combined determination of NT-proBNP and MBF increases the prognostic value of the analysis.