[Possibilities of Predicting Peak Oxygen Consumption in Patients With Chronic Heart Failure According to the 6‑Minute Walk Test]

AIM

To determine the correlation between the results of the 6-minute walk test (6MWT) and peak oxygen consumption (VO2peak) for populations of patients with chronic heart failure with pronounced clinical and demographic differences; to study a possibility of indirect measurement of VO2peak based on the results of 6MWT using the formulas available from the literature.

MATERIAL AND METHODS

Two databases were analyzed: 50 patients included in the AEROFIT study (group A), and 31 patients from the Almazov National Medical Research Center (group B). The inclusion criteria were the availability of data from the cardiopulmonary stress test and the 6MWT. The possibility of predicting VO2peak was calculated based on the results of 6MWT using the formulas reported in the literature (L. P. Cahalin et al., 1996; R. M. Ross et al., 2010; R. A. Adedoyin et al., 2010). The predictive accuracy of the models was assessed using the coefficient of determination (R2). The relationship between functional and clinical-demographic indicators was assessed using the Pearson or Spearman correlation analysis.

RESULTS

The study groups differed significantly in all parameters, except for the proportion of men and the mean VO2peak. Group B patients were 20 years younger than group A patients, had a lower left ventricular ejection fraction (24.06±7.75 and 41.52±10.48 %, respectively; p<0.001), and covered a 130 m shorter distance in the 6MWT. Despite the absence of a significant difference in VO2peak between groups A and B (13.6 and 13.1 ml / kg / min, respectively; p=0.6581), 61 % of group B patients and 20% of group A belonged to Weber functional class IV. In group A, the 6MWT distance correlated closely with VO2peak (R=0.78; p<0.01) and weakly with age (R=0.4) and body mass index (R=0.3). In group B, the 6MWT distance correlated only with VO2peak (R=0.77; p<0.01). For group A, the R.M. Ross et al. model demonstrated high accuracy in determining the mean VO2peak value with a 0.06% prediction error normalized to measured VO2peak. For group B, none of the models showed satisfactory predictive accuracy. The Ross and Cahalin models showed the best coefficients of determination for groups A and B: Group A, Ross et al. (R2=0.58) and Cahalin et al. (R2=0.59); Group B, Ross et al. (R2=0.59) and Cahalin et al. (R2=0.6).

CONCLUSION

In two groups of patients with a statistically insignificant difference in the mean values of VO2peak, the mean values of 6MWT distance were significantly different, although these indicators correlated closely. The VO2peak prediction models showed satisfactory accuracy for estimation of mean VO2, but poor accuracy for estimation of individual values. A better predictive accuracy is determined by similar clinical and demographic characteristics between the training and testing populations, and likely also by models based on larger, more diversified populations.

Molecular background of impairments in skeletal muscle of heart failure patients

Background

Heart failure (HF) is characterised by systematic inflammation and chronic metabolic dysregulation. HF enhances the release of pro-inflammatory cytokines, induces activation of the complement system, production of autoantibodies, and over-expression of the major histocompatibility (MHC) complex class II molecules. It is known that skeletal muscles are exposed to the immunologic injury in disease; and muscle tissue appeared to be affected by HF leading to the muscle weakness and exercise intolerance development. However, molecular abnormalities occurring in HF patients' muscles and the mechanisms underlying its development are not clarified.

Purpose

To understand the molecular mechanisms underlying skeletal muscle immune and non-immune impairments in HF.

Methods

8 health donors and 5 HF patients with reduced ejection fraction (NYHA Class II and III) were enrolled in this study in accordance with the principles under the Declaration of Helsinki (1989). mRNA of skeletal muscle biopsies of gastrocnemius lateralis were sequenced on Illumina HiSeq. RNA-seq analysis was performed using STAR with reference genome GRCh38 and featureCounts program; differentially expressed genes (DEGs) were assessed using R package DESeq2 with FDR=0.01 and log2 fold change (l2fc) &gt;1.5 filter; pathway analysis was performed using clusterProfiler in R (FDR=0.01).

Results

1404 differentially expressed genes distinguish muscles of HF patients and controls. Among upregulated genes there are different classical MHC molecules and specific one HLA-G (l2fc=2) that has been previously shown appeared in muscles under autoimmune myopathies, and potentially protect them. Unregulated DEGs were responsible for the activation of many molecular immunological pathways: type I interferon signaling pathway (16 DEGs out of total 89), regulation of T cell proliferation (14/153), neutrophil degranulation (31/485), granulocyte differentiation (7/32), negative regulation of viral process (11/53), that indicates about specific inflammatory response in HF muscles. Response to hypoxia (22/314) and gluconeogenesis pathways (12/87) were also activated. Downregulated genes include SLC5A1 (l2fc=−4) sodium glucose cotransporter; NRP3 (l2fc=−4) that plays a role in modulating intravascular volume and vascular tone; MMP1 (l2fc=−13) involved in the breakdown of extracellular matrix; the expression of many genes responsible for DNA-repair (44/534) and cilium assembly (34/366) was also suppressed.

Conclusion

Transcriptome analysis shows immunological and non-immunological alterations in HF skeletal muscles and provides the information about molecular mechanisms of its development.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Russian Science Foundation grant

[Physical training in patients with chronic heart failure: level of involvement, as well as psychosocial, anamnestic and iatrogenic factors that determine the motivation to practice]

Introduction Physical exercise (PE) is a necessary part in the treatment of patients with chronic heart failure (CHF), which is stated in the European Society of Cardiology guidelines and the Russian Heart Failure Society guidelines. However, this type of non-drug treatment is still not sufficiently used in HF patients in Russia.Aim To study the current involvement of HF patients in PT and to describe psychosocial factors that influence the patients' willingness to exercise and potential barriers and motivations for PE.Methods This study was designed as an in-moment survey. Patients with CHF who visited clinics in 7 cities of the Russian Federation in 2018 as a part of European Heart Failure Awareness Days were provided with a self-administered questionnaire containing questions about their social and educational status, attitude to PT as a method of treatment, and factors motivating and demotivating them to participation in training sessions. The survey participants were also asked a question about their source of information about exercise in HF. Physicians filled in the items describing HF clinical manifestations (left ventricular ejection fraction (EF) and HF functional class (FC)). Code numbers were used for further identification of the participants and to protect their confidentiality. Statistical analysis was performed with the StatXcat-8 program. Limits of exact confidence intervals (CIs) were provided both for fractions and parameters of polynomial distribution. CI limits for differences and fractions were calculated using MOVER. Age was analyzed using the PAST program.Results The study included 560 patients with HF; 52 % of them were women (mean age, 64; 95 % CI: 63-65 years). Women were 3 years older than men (95 % CI: 1.3-4.9 years). 501 (89.5 %) patients had FC II-III; 265 (49 %) patients had HF with low EF. 350 (62 %) patients had comorbidities: 41.4 % of patients had diabetes mellitus and 25.4 % of patients had arthritis. Only 91 (17 %) patients reported exercising. Patients younger than 65 exercised significantly more frequently than older ones (odds ratio (OR), 1.7, 95 % CI: 1.0-2.7, р&lt;0.001). Patients with higher education had better chances to be involved in PT or were more anxious to start training (OR, 2.7; 95 % CI: 1.6-4.7, р&lt;0.001). The capability for influencing the disease was the major motivation for PT for both sexes. Probability of this answer was 48 % (95 % CI: 33-61) for men and 46 % (95 % CI: 29-63) for women. 62 % of patients indicated poor health as the major barrier for participation in PT. Only 55 % of patients knew that PT could be a method for HF treatment, and only 50 % were informed about that by their physician.Conclusion The factors that positively influence the willingness to exercise include male sex, higher level of education, younger age, and better perception of the own health condition. 62 % of patients indicated poor health as the major barrier for participation in training. On the whole, the awareness of patients about PT benefits for health in HF was low. To our opinion, this was a serious factor of the extremely low involvement of patients in PT. Only 55 % of patients knew that PT could be a method for HF treatment, and, furthermore, only 50 % of patients received this information from their physicians.

[Position Paper. The role of iron deficiency in patients with chronic heart failure and current corrective approaches]

.

[Response predictors for physical training HFrEF patients]

PURPOSE

To identify different types and possible predictors of physical rehabilitation (PR) response in reduced ejection fraction heart failure (HFrEF) patients, selected on the basis of achievement the lactate threshold during cardiopulmonary exercising test (CPET).

METHODS

64 patients, chronic heart failure (CHF) NYHA II-III functional class were included in our study. Mean age 54±12,5 years, body mass index (BMI) 26,5±6,4 kg/m2, ejection fraction (EF) 26,4±1,4 %, NYHA II: III (67 %: 33 % patients). The original estimated results of physical examination, laboratory parameters, CPET, quality of life (QOL), exercise tolerance (ET) and echocardiography (EchoCG). Physical rehabilitation (PR) efficiency was estimated on the basis of peak oxygen uptake (VO2peak), QOL and ET dynamics after 1,3 and 6 months; EF dynamics was estimated after 6 months. Data were statistically processed using software package "Statistika, 9.0".

RESULTS

After 6 months PR EF increased by 7,5±0,5 %, QOL - 17.5±8 points, ET - 9.5±1 points and VO2 peak - 4.4 ml/min/kg, end-diastolic volume decreased by 6±2.0 ml from baseline (p1,2,3,4, respectively). Echocardiography, CPET, QOL and ET improvement revealed a significant number of patients (EF - 48 %, VO2 peak - 64 %, QOL - 64 %, ET - 67 % of patients, respectively). Revealed a strong positive correlation between the initial values of VO2 peak and EF (rEF=0,4, p), and between baseline levels of sodium, haemoglobin and the of PR efficiency (rNa= 0,41, p,0,05; rHb = 0,45, p.