Cardiopulmonary Test As A Component in the Diagnostic Algorithm for Heart Failure with Preserved Left Ventricular Ejection Fraction in Patients with Atrial Fibrillation

Background: Patients with heart failure with preserved ejection fraction account for more than half of all hospitalizations because of heart failure. On the other hand, atrial fibrillation and heart failure are quite often diagnosed together and one disease influences the development of the other. Timely and accurate diagnosis of heart failure with preserved ejection fraction is the basis for effective treatment of this category of patients. In 2019, the HFA-PEFF algorithm of diagnosis heart failure with preserved ejection fraction (including patients with atrial fibrillation) was proposed. However, the algorithm implies cardiac catheterization in patients at intermediate risk, which involves certain difficulties and cannot be used in routine practice. As an alternative to cardiac catheterization in the diagnosis of heart failure with preserved ejection fraction, we proposed a noninvasive diagnostic method — cardiopulmonary test. However, the value of cardiopulmonary test technique has not been conclusively studied, especially in patients with a combination of chronic heart failure and atrial fibrillation. Aim: The aim of the study was to evaluate the role of the cardiopulmonary test in the diagnosis of heart failure with preserved ejection fraction in patients with atrial fibrillation. Methods: 138 patients with atrial fibrillation were included in our study. Using HFA-PEFF algorithm (algorithm for diagnosis of heart failure with preserved left ventricular ejection fraction) all patients were initially divided into 3 groups: low probability of heart failure — 23 patients, intermediate probability — 96 and high probability — 19 patients. The stress-test allowed to precisely assess of patients at intermediate risk and finally form the groups: Group 1 without heart failure, 85 patients (61.6%); Group 2 patients with heart failure and preserved ejection fraction, 53 patients (38.4%). The next diagnostic stage was cardiopulmonary test. Results: During cardiopulmonary test, the anaerobic exercise threshold was 6.8 and 4.85 METs for the first and second groups, respectively (p <0.001), reflecting lower exercise tolerance in the second group of patients. Analysis of variance (ANOVA) demonstrated a statistically significant increase in pro-BNP levels with a decrease in peak VO₂ (p <0.001). Also, analysis of variance demonstrated a significant statistical difference with respect to systolic pulmonary artery pressure in the subgroups with severely, moderately reduced oxygen consumption and in the group with normal peak VO₂ (p=0.01). ROC analysis determined a peak VO₂ of 20 ml/kg/min, above which the HFA-PEFF algorithm was unlikely to detect heart failure (AUC 0.73; confidence interval 0.65–0.82; p=0.043; sensitivity 85%; specificity 51%). Conclusion: The cardiopulmonary test is a reliable instrumental non-invasive method in the diagnosis of heart failure with preserved ejection fraction.