Identifying Putative Biomarkers of Foodborne Pathogens Using a Metabolomic Approach.

Metabolomics is the study of low molecular weight biochemical molecules (typically <1500 Da) in a defined biological organism or system. In case of food systems, the term "food metabolomics" is often used. Food metabolomics has been widely explored and applied in various fields including food analysis, food intake, food traceability, and food safety. Food safety applications focusing on the identification of pathogen-specific biomarkers have been promising. This chapter describes a nontargeted metabolite profiling workflow using gas chromatography coupled with mass spectrometry (GC-MS) for characterizing three globally important foodborne pathogens, Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica, from selective enrichment liquid culture media. The workflow involves a detailed description of food spiking experiments followed by procedures for the extraction of polar metabolites from media, the analysis of the extracts using GC-MS, and finally chemometric data analysis using univariate and multivariate statistical tools to identify potential pathogen-specific biomarkers.

Distinct Communities of Bacteria and Unicellular Eukaryotes in the Different Water Masses of Cretan Passage Water Column (Eastern Mediterranean Sea).

Elucidating marine microbiota diversity and dynamics holds significant importance due to their role in maintaining vital ecosystem functions and services including climate regulation. This work aims to contribute in the understanding of microbial ecology and networking in one of the world's most understudied marine regions, the Eastern Mediterranean Sea. High-throughput 16S and 18S rRNA gene sequencing analysis was applied to study the diversity of bacteria and unicellular eukaryotes in the different water masses of the Cretan Passage during two seasonally-different sampling expeditions. We assumed that microbial associations differ between the surface and deepwater masses and created co-occurrence networks to evaluate this hypothesis. Our results unveiled vertical variations in both bacterial and unicellular eukaryotic diversity with species fluctuations indicative of seasonality being recorded in the surface water mass. Heterotrophic taxa and grazers related to organic matter degradation and nutrient cycling were enriched in the deepest water layers. Moreover, surface waters presented a higher number of microbial associations indicating abundant ecological niches compared to the deepest layer, possibly related to the lack of bottom-up resources in the oligotrophic deep ocean. Overall, our data provide insight in a heavily stressed, yet underexplored, marine area that requires further research to unravel the ecological roles of marine microbes. To our knowledge, this is the first study that combines molecular biology tools to provide data on both planktic prokaryotes and unicellular eukaryotes across the different water masses in this marine region of the Eastern Mediterranean basin.

Atrial fibrillation burden: Stepping beyond the categorical characterization.

Traditional classifications categorize atrial fibrillation (AF) into paroxysmal, persistent, or permanent, but recent advancements in monitoring have revealed AF as a continuous variable, challenging existing paradigms. AF burden, defined basically as the amount of time spent in AF during a monitored period, has emerged as a crucial metric. This review assesses the evolving landscape of AF burden and its measurement methods, diagnostic modalities, and impact on outcomes. Guidelines suggest individualized approaches, combining AF burden with clinical scores (CHA2DS2-VASc), but studies have challenged this. Addressing the impact of AF burden on patients' quality of life before or after ablation is also crucial. Although continuous monitoring technologies offer promising avenues, the field faces challenges, such as defining clinically relevant thresholds. Future research should focus on refining these, designing trials centered around AF burden, and evaluating the efficacy of interventions in reducing AF burden, ultimately paving the way for personalized management strategies.

Remote Monitoring of Cardiac Implantable Electronic Devices in Very Elderly Patients: Advantages and Specific Problems.

Cardiac implantable electronic devices (CIEDs) offer the benefit of remote monitoring and decision making and find particular applications in special populations such as the elderly. Less transportation, reduced costs, prompt diagnosis, a sense of security, and continuous real-time monitoring are the main advantages. On the other hand, less physician-patient interactions and the technology barrier in the elderly pose specific problems in remote monitoring. CIEDs nowadays are abundant and are mostly represented by rhythm control/monitoring devices, whereas hemodynamic remote monitoring devices are gaining popularity and are evolving and becoming refined. Future directions include the involvement of artificial intelligence, yet disparities of availability, lack of follow-up data, and insufficient patient education are still areas to be improved. This review aims to describe the role of CIED in the very elderly and highlight the merits and possible drawbacks.

The Relationship of Adherence to the Mediterranean Diet with Disease Activity and Quality of Life in Crohn's Disease Patients.

Background and Objectives: Emerging evidence is placing the Mediterranean diet (MD) in the spotlight as a potential dietary model that could benefit inflammatory bowel disease (IBD) patients in terms of prevention and progress of the disease. The main aim of the present study is to shed some light on the relationship between the adherence to the MD and the degree of disease activity, as well as the quality of life in patients with Crohn's disease (CD). Materials and Methods: An administered questionnaire was used to assess and record a number of parameters, including recent medical and weight history, anthropometric characteristics, disease activity (in remission or active disease), and quality of life of both male and female CD patients. Moreover, the level of compliance of the participants to the Mediterranean diet model was evaluated and its relationship with disease activity and quality of life was investigated. Results: Adherence to the MD was significantly higher in patients with inactive disease than in those with active disease (p = 0.019). According to the correlation analysis conducted, adherence to the MD was negatively correlated with disease activity (p = 0.039) and positively correlated with quality of life (QoL) (p = 0.046) of the participants. Intake of fruits, vegetables, and dairy products was significantly higher in remission patients (p = 0.046, p = 0.001, p = 0.041, respectively). Conclusions: We conclude, according to the findings of the study, that adherence to the MD is associated with disease activity and QoL in patients with CD. Future research should focus on MD intervention studies on IBD patients in order to assess its effect on modulating disease activity/course and related inflammatory biomarkers.

Is premorbid stress assessed by hair cortisol concentration linked to Takotsubo syndrome? Results from a pilot study.

INTRODUCTION: The pathophysiology of Takotsubo syndrome (TTS) is not completely understood and the role of chronic stress is among the main mechanistic links. The aim of this study was to explore whether accumulating hair cortisol concentration (HCC), a novel biomarker of chronic stress, is associated with the occurrence of TTS. METHODS: A consecutive series of 18 TTS patients and 36 age and sex matched healthy controls were included in our analysis. Hair samples were collected from participants'' vertex. The proximal 2.5 cm of hair was cut in equal parts of 0.5 cm, reflecting mean cortisol levels in time intervals of 0-15, 15-30, 30-45, 45-60 and 60-75 days prior to hair collection. RESULTS: HCC was higher in TTS group compared to controls at any time point and increased over time starting from 75 days prior to the event. The rate of HCC increase was significantly higher in TTS patients versus controls (beta of interaction = 0.48; 95%CI: 0.36-0.60; p < 0.001). CONCLUSIONS: The steadily increasing trend of HCC in TTS patients suggests that the additive effect of multiple stressful events over several weeks prior TTS onset may disrupt cortisol homeostasis and play a role in TTS pathophysiology.

Plant Biostimulants Enhance Tomato Resilience to Salinity Stress: Insights from Two Greek Landraces.

Salinity, one of the major abiotic stresses in plants, significantly hampers germination, photosynthesis, biomass production, nutrient balance, and yield of staple crops. To mitigate the impact of such stress without compromising yield and quality, sustainable agronomic practices are required. Among these practices, seaweed extracts (SWEs) and microbial biostimulants (PGRBs) have emerged as important categories of plant biostimulants (PBs). This research aimed at elucidating the effects on growth, yield, quality, and nutrient status of two Greek tomato landraces ('Tomataki' and 'Thessaloniki') following treatments with the Ascophyllum nodosum seaweed extract 'Algastar' and the PGPB 'Nitrostim' formulation. Plants were subjected to bi-weekly applications of biostimulants and supplied with two nutrient solutions: 0.5 mM (control) and 30 mM NaCl. The results revealed that the different mode(s) of action of the two PBs impacted the tolerance of the different landraces, since 'Tomataki' was benefited only from the SWE application while 'Thessaloniki' showed significant increase in fruit numbers and average fruit weight with the application of both PBs at 0.5 and 30 mM NaCl in the root zone. In conclusion, the stress induced by salinity can be mitigated by increasing tomato tolerance through the application of PBs, a sustainable tool for productivity enhancement, which aligns well with the strategy of the European Green Deal.

Prediction of heart failure patients with distinct left ventricular ejection fraction levels using circadian ECG features and machine learning.

Heart failure (HF) encompasses a diverse clinical spectrum, including instances of transient HF or HF with recovered ejection fraction, alongside persistent cases. This dynamic condition exhibits a growing prevalence and entails substantial healthcare expenditures, with anticipated escalation in the future. It is essential to classify HF patients into three groups based on their ejection fraction: reduced (HFrEF), mid-range (HFmEF), and preserved (HFpEF), such as for diagnosis, risk assessment, treatment choice, and the ongoing monitoring of heart failure. Nevertheless, obtaining a definitive prediction poses challenges, requiring the reliance on echocardiography. On the contrary, an electrocardiogram (ECG) provides a straightforward, quick, continuous assessment of the patient's cardiac rhythm, serving as a cost-effective adjunct to echocardiography. In this research, we evaluate several machine learning (ML)-based classification models, such as K-nearest neighbors (KNN), neural networks (NN), support vector machines (SVM), and decision trees (TREE), to classify left ventricular ejection fraction (LVEF) for three categories of HF patients at hourly intervals, using 24-hour ECG recordings. Information from heterogeneous group of 303 heart failure patients, encompassing HFpEF, HFmEF, or HFrEF classes, was acquired from a multicenter dataset involving both American and Greek populations. Features extracted from ECG data were employed to train the aforementioned ML classification models, with the training occurring in one-hour intervals. To optimize the classification of LVEF levels in coronary artery disease (CAD) patients, a nested cross-validation approach was employed for hyperparameter tuning. HF patients were best classified using TREE and KNN models, with an overall accuracy of 91.2% and 90.9%, and average area under the curve of the receiver operating characteristics (AUROC) of 0.98, and 0.99, respectively. Furthermore, according to the experimental findings, the time periods of midnight-1 am, 8-9 am, and 10-11 pm were the ones that contributed to the highest classification accuracy. The results pave the way for creating an automated screening system tailored for patients with CAD, utilizing optimal measurement timings aligned with their circadian cycles.

Physiological Changes in QRS Fragmentation in Athletes and Nonathletes without Cardiac Disease.

Background/Objectives: QRS fragmentation has not been linked with increased mortality in individuals without known cardiac disease. We aimed to investigate the physiological determinants of QRS fragmentation in individuals without cardiac disease. Methods: Study participants were 163 (54 athletes, 109 nonathletes) asymptomatic individuals with QRS fragmentation but without cardiac disease. QRS fragmentation was assessed in the supine position after deep inspiration or standing up and during exercise. The changes in QRS fragmentation were evaluated over a median follow-up period of 2.3 (0.8-4.9) years. Results: The most common lead with QRS fragmentation was III (63.0% in athletes, 61.5% in nonathletes), immediately followed by V1 (50.0%) and aVF (42.6%) in athletes and aVF (55.0%) in nonathletes. QRS fragmentation in V1 was more frequent in athletes compared to nonathletes (p < 0.001). Among athletes, the presence of QRS fragmentation in V1 could be independently predicted by increased RVOTproxi (right ventricular outflow tract proximal diameter indexed to body surface area) (p < 0.001). Among individuals with QRS fragmentation in V1, deep inspiration resulted in disappearance of QRS fragmentation more frequently in nonathletes compared to athletes (100% vs. 20%, p = 0.003). Deep inspiration resulted in disappearance of QRS fragmentation in aVF (p < 0.001). The presence of QRS fragmentation in II or aVF was associated with increased body mass index (BMI) (p = 0.003). Among athletes without QRS fragmentation in V1 at baseline, the appearance of QRS fragmentation in V1 at the end of follow-up was associated with greater training age (p = 0.034). Among individuals with QRS fragmentation in aVF at baseline, the disappearance of QRS fragmentation in aVF at the end of follow-up was associated with greater reduction in BMI (p = 0.008). Conclusions: The characteristic feature of QRS fragmentation in athletes was the presence of QRS fragmentation in V1, which was associated with RVOTproxi. The persistence of QRS fragmentation in V1 after deep inspiration could serve as a specific marker of exercise-training-related cardiac adaptation. The presence of QRS fragmentation in the leads of the frontal plane was influenced by BMI and respiration phase.

Curcumin as a Multifunctional Spice Ingredient against Mental Disorders in Humans: Current Clinical Studies and Bioavailability Concerns.

BACKGROUND: Mental disorders in terms of depression, anxiety, and stress are one of the major causes of burden globally. Over the last two decades, the use of plant-based substances in the treatment of mental disorders in combination or not with medication has increasingly attracted the interest of the scientific research community. However, even if there is a plethora of naturally occurring bioactive compounds, most of them have low bioavailability, rendering them unable to insert into the bloodstream to exert their biological activities. METHODS: This is a comprehensive narrative review that critically summarizes and scrutinizes the new approaches to the treatment of mental disorders using curcumin, also highlighting its bioavailability properties. The most accurate were searched using effective and relevant keywords. RESULTS: This narrative review reveals substantial evidence that curcumin can exert significant effects on several mental disorders. However, despite the low cost, the extensive and confirmed potency of curcumin and its involvement in signaling pathways and the scientifically confirmed data regarding its molecular mechanisms of action against mental disorders, this naturally occurring compound presents low oral bioavailability. Pharmaceutical technology has provided solutions to increase the bioavailability of curcumin. Combination with piperine, galactomannosides, liposomal formulation or nanoformulation overcomes the bioavailability and solubility disadvantages. CONCLUSIONS: Although curcumin demonstrates anti-anxiety, anti-depressive and anti-stress properties, studies on humans are limited and heterogeneous. Further research is highly recommended to determine the most functional formula, dose, duration, and possible side effects of curcumin on mental disorders in humans. Based on the current knowledge, the curcumin nanoformulation and Theracurmin, a form of colloidal submicroscopic particles, seem to be the most effective bioavailable formulations, which may be examined in future clinical human studies.

Newly detected diabetes mellitus patients with acute coronary syndrome have an adverse cardiometabolic profile similar to patients with prior diabetes and a more extensive ischemic myocardial insult.

AIMS: The impact of newly detected diabetes mellitus (NDDM) on metabolic parameters and extent of myocardial necrosis in patients with acute coronary syndrome (ACS) is not fully explored. We examined the impact of NDDM on cardiometabolic characteristics and myocardial necrosis in ACS patients. METHODS: CALLINICUS-Hellas Registry is an ongoing prospective multicenter observational study evaluating the adherence to lipid-lowering therapy (LLT) among ACS patients in Greece. Three groups were created: a) patients with NDDM (abnormal fasting glucose, HbA1c ≥ 6.5 % and no previous history of DM), b) patients without known DM and HbA1c < 6.5 % (non-DM) and c) patients with prior DM. RESULTS: The prevalence of NDDM among 1084 patients was 6.9 %. NDDM patients had lower HDL-C [38 (32-45) vs 42 (36-50) mg/dL] and higher triglycerides levels [144 (104-231) vs 115 (87-152) mg/dL] compared to non-DM patients (p < 0.05). NDDM patients featured both higher body mass index [29.5 (26.4-34.3) vs 27.1 (24.9-29.9) kg/m2] and waist circumference [107 (100-114) vs 98 (91-106) cm] compared to non-DM patients (p < 0.05). In addition, NDDM patients had more extensive myocardial necrosis than patients with prior DM. CONCLUSIONS: ACS patients with NDDM have an adverse cardiometabolic profile similar to patients with prior DM and have more extensive myocardial insult.

Circadian assessment of heart failure using explainable deep learning and novel multi-parameter polar images.

BACKGROUND AND OBJECTIVE: Heart failure (HF) is a multi-faceted and life-threatening syndrome that affects more than 64.3 million people worldwide. Current gold-standard screening technique, echocardiography, neglects cardiovascular information regulated by the circadian rhythm and does not incorporate knowledge from patient profiles. In this study, we propose a novel multi-parameter approach to assess heart failure using heart rate variability (HRV) and patient clinical information. METHODS: In this approach, features from 24-hour HRV and clinical information were combined as a single polar image and fed to a 2D deep learning model to infer the HF condition. The edges of the polar image correspond to the timely variation of different features, each of which carries information on the function of the heart, and internal illustrates color-coded patient clinical information. RESULTS: Under a leave-one-subject-out cross-validation scheme and using 7,575 polar images from a multi-center cohort (American and Greek) of 303 coronary artery disease patients (median age: 58 years [50-65], median body mass index (BMI): 27.28 kg/m2 [24.91-29.41]), the model yielded mean values for the area under the receiver operating characteristics curve (AUC), sensitivity, specificity, normalized Matthews correlation coefficient (NMCC), and accuracy of 0.883, 90.68%, 95.19%, 0.93, and 92.62%, respectively. Moreover, interpretation of the model showed proper attention to key hourly intervals and clinical information for each HF stage. CONCLUSIONS: The proposed approach could be a powerful early HF screening tool and a supplemental circadian enhancement to echocardiography which sets the basis for next-generation personalized healthcare.

Physical signs and atherosclerotic cardiovascular disease in familial hypercholesterolemia: the HELLAS-FH Registry.

AIMS: Three physical signs, namely tendon xanthomas, corneal arcus and xanthelasma, have been associated with heterozygous familial hypercholesterolemia (heFH). The prevalence and clinical significance of these signs are not well established among contemporary heFH individuals. This study explored the frequency as well as the association of these physical signs with prevalent atherosclerotic cardiovascular disease (ASCVD) in heFH individuals. METHODS: Data from the Hellenic Familial Hypercholesterolemia Registry were applied for this analysis. The diagnosis of heFH was based on the Dutch Lipid Clinic Network Score. Multivariate logistic regression analysis was conducted to examine the association of heFH-related physical signs with prevalent ASCVD. RESULTS: Adult patients ( n  = 2156, mean age 50 ±â€Š15 years, 47.7% women) were included in this analysis. Among them, 14.5% had at least one heFH-related physical sign present. The prevalence of corneal arcus before the age of 45 years was 6.6%, tendon xanthomas 5.3%, and xanthelasmas 5.8%. Among physical signs, only the presence of corneal arcus before the age of 45 years was independently associated with the presence of premature coronary artery disease (CAD). No association of any physical sign with total CAD, stroke or peripheral artery disease was found. Patients with physical signs were more likely to receive higher intensity statin therapy and dual lipid-lowering therapy, but only a minority reached optimal lipid targets. CONCLUSION: The prevalence of physical signs is relatively low in contemporary heFH patients. The presence of corneal arcus before the age of 45 years is independently associated with premature CAD.

Atherosclerosis and depression: is carotid intima-media thicker in patients with depression compared to matched control individuals? A systematic review and meta-analysis.

OBJECTIVE: To investigate if there is an association between atherosclerosis and depression by using as imaging biomarker the carotid intima media thickness (cIMT), a surrogate marker for atherosclerosis. METHODS: PubMed/Medline, Embase and Cochrane databases were comprehensively searched to identify studies investigating the association between cIMT and depression. The results were pooled using a random-effects statistical model, appropriate for the expected high heterogeneity. Sensitivity and subgroup analyses were conducted where data was available. RESULTS: Overall, 22 and 13 studies met inclusion criteria for the qualitative and the quantitative synthesis, respectively, with a total of 4466 patients and 21,635 control participants. Results showed that cIMT is significantly higher in the depression, compared to the control groups with an overall mean difference of 0.07 mm (95% CI 0.04-0.10, p < 0.01). Subgroup analysis showed that diabetes could present as a confounding factor in patients with depression and an increased cIMT. CONCLUSIONS: This study confirms a significantly increased cIMT in patients with depression, compared with controls and suggests a possible bidirectional link between atherosclerosis and depression. An early screening of cardiovascular disease in individuals suffering with depression should be considered.

Socioeconomic Deprivation and the Risk of Sight-Threatening Diabetic Retinopathy: A Population-Based Cohort Study in the U.K.

OBJECTIVE: To evaluate the associations between socioeconomic deprivation and sight-threatening diabetic retinopathy (STDR) in individuals with type 1 diabetes (T1D) and type 2 diabetes (T2D). RESEARCH DESIGN AND METHODS: Data from 175,628 individuals with diabetes in the Health Improvement Network were used to assess the risk of STDR across Townsend Deprivation Index quantiles using Cox proportional hazard regression. RESULTS: Among individuals with T1D, the risk of STDR was three times higher (adjusted hazard ratio [aHR] 2.67, 95% CI 1.05-7.78) in the most deprived quintile compared with the least deprived quintile. In T2D, the most deprived quintile had a 28% higher risk (aHR 1.28; 95% CI 1.15-1.43) than the least deprived quintile. CONCLUSIONS: Increasing socioeconomic deprivation is associated with a higher risk of developing STDR in people with diabetes. This underscores persistent health disparities linked to poverty, even within a country offering free universal health care. Further research is needed to address health equity concerns in socioeconomically deprived regions.

Gender Differences Among Very Young Patients With Acute Coronary Syndrome: Long-Term Follow-Up of the STAMINA Study.

The rate of hospitalization for acute coronary syndrome (ACS) among young patients is increasing. Healthcare disparities remain unsolved among female patients. We explored gender differences regarding risk factors, clinical presentation, in-hospital treatment, and long-term outcomes among ACS patients. A total of 445 patients with very early ACS (men ≤ 35 years and women ≤ 40 years of age) were followed for a median of 5 years. Primary clinical endpoint was the composite of cardiac death, non-fatal myocardial infarction, stroke, and coronary revascularization. Women accounted for 16% of cases. Smoking was the most prevalent risk factor, 56% and 60% of the females and males, respectively, continued to smoke after ACS. Chest pain was typical in 85% and 83% of the female and male patients, respectively. In-hospital treatment (pharmacological and reperfusion) as well as the composite clinical endpoint during follow-up did not differ between female and male patients. Lipid-lowering therapy was suboptimal in both genders, and persistence of smoking was the sole predictor for the composite clinical endpoint (hazard ratio: 2.30 [95% CI: 1.26-4.20]; P = .007). In conclusion, in-hospital treatment was similar between male and female patients. However, the majority of them continued smoking, and this was an independent predictor for future adverse outcomes.

Experimentally-guided in silico design of engineered heart tissues to improve cardiac electrical function after myocardial infarction.

Engineered heart tissues (EHTs) built from human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) showed promising results for cardiac function restoration following myocardial infarction. Nevertheless, human iPSC-CMs have longer action potential and lower cell-to-cell coupling than adult-like CMs. These immature electrophysiological properties favor arrhythmias due to the generation of electrophysiological gradients when hiPSC-CMs are injected in the cardiac tissue. Culturing hiPSC-CMs on three-dimensional (3D) scaffolds can promote their maturation and influence their alignment. However, it is still uncertain how on-scaffold culturing influences the overall electrophysiology of the in vitro and implanted EHTs, as it requires expensive and time consuming experimentation. Here, we computationally investigated the impact of the scaffold design on the EHT electrical depolarization and repolarization before and after engraftment on infarcted tissue. We first acquired and processed electrical recordings from in vitro EHTs, which we used to calibrate the modeling and simulation of in silico EHTs to replicate experimental outcomes. Next, we built in silico EHT models for a range of scaffold pore sizes, shapes (square, rectangular, auxetic, hexagonal) and thicknesses. In this setup, we found that scaffolds made of small (0.2 mm2), elongated (30° half-angle) hexagons led to faster EHT activation and better mimicked the cardiac anisotropy. The scaffold thickness had a marginal role on the not engrafted EHT electrophysiology. Moreover, EHT engraftment on infarcted tissue showed that the EHT conductivity should be at least 5% of that in healthy tissue for bidirectional EHT-myocardium electrical propagation. For conductivities above such threshold, the scaffold made of small elongated hexagons led to the lowest activation time (AT) in the coupled EHT-myocardium. If the EHT conductivity was further increased and the hiPSC-CMs were uniformly oriented parallel to the epicardial cells, the total AT and the repolarization time gradient decreased substantially, thus minimizing the likelihood for arrhythmias after EHT transplantation.

Ergophysiological evaluation of heart failure patients with reduced ejection fraction undergoing exercise-based cardiac rehabilitation: A systematic review and meta-analysis.

BACKGROUND: This systematic review and meta-analysis aims to explore in heart failure (HF) patients with reduced ejection fraction (EF) undergoing exercise-based cardiac rehabilitation the following: 1) the comparison of temporal changes between peak oxygen uptake (VO2peak) and first ventilatory threshold (VO2VT1), 2) the association of VO2peak and VO2VT1 changes with physiological factors, and 3) the differential effects of continuous aerobic exercise (CAE) and interval training (IT) on VO2peak and VO2VT1. METHODS: A systematic literature search was conducted in PubMed, CENTRAL, and Scopus. Inclusion criteria were 1) original research articles using exercise-based cardiac rehabilitation, 2) stable HF patients with reduced EF, 3) available values of VO2peak and VO2VT1 (in mL/kg/min) both at baseline and after exercise training with comparison between these time points. RESULTS: Among the 30 eligible trials, 24 used CAE, 5 IT, and one CAE and IT. Multivariable meta-regression with duration of exercise training and percentage of males as independent variables and the change in VO2peak as a dependent variable showed that the change in VO2peak was negatively associated with duration of exercise training (coefficient=-0.061, p=0.027), implying the possible existence of a waning effect of exercise training on VO2peak in the long term. Multivariable meta-regression demonstrated that both age (coefficient=-0.140, p<0.001) and EF (coefficient=-0.149, p<0.001) could predict the change in VO2VT1, whereas only age (coefficient=-0.095, p=0.022), but not EF (coefficient = 0.082, p = 0.100), could predict the change in VO2peak. The posttraining peak respiratory exchange ratio, as an index of maximum effort during exercise testing, correlated positively with the change in VO2peak (coefficient=-0.021, p=0.044). The exercise-induced changes of VO2peak (p = 0.438) and VO2VT1 (p = 0.474) did not differ between CAE and IT groups. CONCLUSIONS: Improvement of endurance capacity during cardiac rehabilitation may be detected more accurately with the assessment of VO2VT1 rather than VO2peak.