Prognostic respiratory parameters in heart failure patients with and without exercise oscillatory ventilation — A systematic review and descriptive meta-analysis

Minute Ventilation/Carbon Dioxide Production Slope Could Predict Short- and Long-Term Prognosis of Patients After Acute Decompensated Heart Failure

(1) Background: Heart failure (HF) leads to functional disability and major cardiovascular events (MACEs). Cardiopulmonary exercise testing (CPET) is the gold standard for assessing aerobic capacity and prognostic stratification. This study aimed to evaluate the predischarge CPET variables in patients with acute decompensated HF and identify the submaximal CPET variables with prognostic value. (2) Methods: A retrospective cohort study was conducted at a tertiary center in Taiwan. Patients surviving their first episode of decompensated HF and undergoing predischarge CPET (February 2017 to January 2023) were analyzed. Follow-up was conducted until a MACE or administrative censoring (up to 5 years). Cox regression identified the significant predictors of MACE. (3) Results: The study included 553, 485, and 267 patients at the 3-month, 1-year, and 5-year follow-ups, respectively. MACE rates were 15.0%, 34.2%, and 50.9%. The VE/VCO2 slope was a significant predictor of MACE at all intervals. A VE/VCO2 slope >38.95 increased the risk of MACE by 2.49-fold at 3 months and 1.81-fold at 1 year (both p < 0.001). A slope > 37.35 increased the 5-year MACE risk by 1.75-fold (p = 0.002). (4) Conclusions: The VE/VCO2 slope is a significant submaximal CPET predictor of MACE in patients post-acute decompensated HF for both short- and long-term outcomes.

Utility of focused cardiac ultrasonography training in veterinary students to differentiate stages of subclinical myxomatous mitral valve disease in dogs

BACKGROUND

Differentiation of the subclinical phases of myxomatous mitral valve disease (MMVD) in dogs relies heavily on echocardiography. Focused cardiac ultrasonography (FCU) is a point-of-care technique that can assess heart size.

HYPOTHESIS/OBJECTIVES

Veterinary students trained in FCU can differentiate dogs with subclinical MMVD based on left ventricular (LV) and left atrial (LA) dimensions.

ANIMALS

Forty-eight dogs with subclinical MMVD.

METHODS

Veterinary students were trained to measure LV dimension and LA-to-aortic root dimension ratio (LA : Ao) using FCU. Dogs were categorized into 2 cohorts based on whether or not the LV normalized internal diastolic dimension was ≥1.7 and LA : Ao was ≥1.6. Agreement between FCU and echocardiographic studies performed by cardiologists was evaluated.

RESULTS

One-hundred and forty-six FCU examinations were performed by 58 veterinary students on 48 dogs. Overall agreement between students and cardiologists was moderate (Fleiss' kappa, 0.54; 95% confidence interval [CI], 0.39-0.69; P < .001). Percentage accuracy in observations with heart dimensions less than the cutoffs (86/89, 97%) was significantly higher than in observations in with larger hearts (31/57, 54%; P < .001). Agreement increased from moderate to good as heart sizes became more extreme. Degree of confidence by students in performing FCU was significantly higher at the end vs start of the study.

CONCLUSIONS AND CLINICAL IMPORTANCE

Categorization of dogs with subclinical MMVD by veterinary students using FCU was associated with moderate to good agreement with echocardiography. Focused cardiac ultrasonography is a point-of-care method that can help assess clinical stage in dogs with subclinical MMVD.

Software development to standardize the clinical diagnosis of exercise oscillatory ventilation in heart failure

BACKGROUND

Exercise oscillatory ventilation (EOV) is characterized by periodic oscillations of minute ventilation during cardiopulmonary exercise testing (CPET). Despite its prognostic value in chronic heart failure (HF), its diagnosis is complex due to technical limitations. An easier and more accurate way of EOV identification can contribute to a better approach and clinical diagnosis. This study aims to describe a software development to standardize the EOV diagnosis from CPET's raw data in heart failure patients and test its reliability (intra- and inter-rater).

METHODS

The software was developed in the "drag-and-drop" G-language using LabVIEW®. Five EOV definitions (Ben-Dov, Corrà, Kremser, Leite, and Sun definitions), two alternative approaches, one smoothing technique, and some basic statistics were incorporated into the interface to visualize four charts of the ventilatory response. EOV identification was based on a set of criteria verified from the interaction between amplitude, cycle length, and oscillation time. Two raters analyzed the datasets. In addition, repeated measurements were verified after six months using about 25% of the initial data. Cohen's kappa coefficient (κ) was used to investigate the reliability.

RESULTS

Overall, 391 tests were analyzed in duplicate (inter-rater reliability) and 100 tests were randomized for new analysis (intra-rater reliability). High inter-rater (κ > 0.80) and intra-rater (κ > 0.80) reliability of the five EOV diagnoses were observed.

CONCLUSION

The present study proposes novel semi-automated software to detect EOV in HF, with high inter and intra-rater agreements. The software project and its tutorial are freely available for download.

Exercise oscillatory ventilation in patients with coexisting chronic obstructive pulmonary disease and heart failure: Clinical implications

BACKGROUND

Exercise oscillatory ventilation (EOV) is considered an important variable for predicting poor prognosis in patients with heart failure (HF) with reduced left ventricular ejection fraction (HFrEF). However, there are no studies evaluating EOV presence in the coexistence chronic obstructive pulmonary disease (COPD) and HFrEF.

AIMS

I) To compare the clinical characteristics of participants with coexisting HFrEF-COPD with and without EOV during cardiopulmonary exercise testing (CPET); and II) to identify the impact of EOV on mortality during follow-up for 35 months.

METHODS

50 stable HFrEF-COPD (EF<50%) participants underwent CPET and were followed for 35 months. The parametric Student's t-test, chi-square tests, linear regression model and Kaplan-Meier analysis were applied.

RESULTS

We identified 13 (26%) participants with EOV and 37 (74%) without EOV (N-EOV) during exercise. The EOV group had worse cardiac function (LVEF: 30 ± 6% vs. N-EOV 40 ± 9%, p = 0.007), worse pulmonary function (FEV1: 1.04 ± 0.7 L vs. N-EOV 1.88 ± 0.7 L, p = 0.007), a higher mortality rate [7 (54%) vs. N-EOV 8 (27%), p = 0.02], higher minute ventilation/carbon dioxide production (V̇˙E/ V̇˙ CO2) slope (42 ± 7 vs. N-EOV 36 ± 8, p = 0.04), reduced peak ventilation (L/min) (26.2 ± 16.7 vs. N-EOV 40.3 ± 16.4, p = 0.01) and peak oxygen uptake (mlO2 kg-1 min-1) (11.0 ± 4.0 vs. N-EOV 13.5 ± 3.4 ml●kg-1●min-1, p = 0.04) when compared with N-EOV group. We found that EOV group had a higher risk of mortality during follow-up (long-rank p = 0.001) than patients with N-EOV group.

CONCLUSION

The presence of EOV is associated with greater severity of coexisting HFrEF and COPD and a reduced prognosis. Assessment of EOV in participants with coexisting HFrEF-COPD, as a biomarker for both clinical status and prognosis may therefore be warranted.

Prognostic Role of Metabolic Exercise Testing in Heart Failure

Heart failure is a clinical syndrome with significant heterogeneity in presentation and severity. Serial risk-stratification and prognostication can guide management decisions, particularly in advanced heart failure, when progression toward advanced therapies or end-of-life care is warranted. Each currently utilized prognostic marker carries its own set of challenges in acquisition, reproducibility, accuracy, and significance. Left ventricular ejection fraction is foundational for heart failure syndrome classification after clinical diagnosis and remains the primary parameter for inclusion in most clinical trials; however, it does not consistently correlate with symptoms and functional capacity, which are also independently prognostic in this patient population. Utilizing the left ventricular ejection fraction as the sole basis of prognostication provides an incomplete characterization of this condition and is prone to misguide medical decision-making when used in isolation. In this review article, we survey and exposit the important role of metabolic exercise testing across the heart failure spectrum, as a complementary diagnostic and prognostic modality. Metabolic exercise testing, also known as cardiopulmonary exercise testing, provides a comprehensive evaluation of the multisystem (i.e., neurological, respiratory, circulatory, and musculoskeletal) response to exercise performance. These differential responses can help identify the predominant contributors to exercise intolerance and exercise symptoms. Additionally, the aerobic exercise capacity (i.e., oxygen consumption during exercise) is directly correlated with overall life expectancy and prognosis in many disease states. Specifically in heart failure patients, metabolic exercise testing provides an accurate, objective, and reproducible assessment of the overall circulatory sufficiency and circulatory reserve during physical stress, being able to isolate the concurrent chronotropic and stroke volume responses for a reliable depiction of the circulatory flow rate in real time.

The Need for Breathing Training Techniques: The Elephant in the Heart Failure Cardiac Rehabilitation Room: A Randomized Controlled Trial

BACKGROUND

Although solid evidence has indicated that respiratory symptoms are common amongst patients with chronic heart failure (CHF), state-of-the-art cardiac rehabilitation (CR) programs do not typically include management strategies to address respiratory symptoms. This study investigated the effect of the addition of breathing exercises (BE) to the CR programs in CHF.

METHODS

In a two parallel-arm randomized controlled study (RCT), 40 middle-aged patients with CHF and respiratory symptoms were recruited and randomized into two equal groups (n = 20); group (A): standard CR with BE and group (B): standard CR alone. Primary outcomes were respiratory parameters and secondary outcomes included cardiovascular and cardiopulmonary outcomes. All the participants attended a program of aerobic exercise (three sessions/week, 60-75% MHR, 45-55 min) for 12 weeks, plus educational, nutritional, and psychological counseling. Group (A) patients attended the same program together with BE using inspiratory muscle training (IMT) and breathing calisthenics (BC) (six sessions/week, 15-25 min) for the same duration.

RESULTS

There was a significant improvement in the respiratory outcomes, and most of the cardiovascular and cardiopulmonary outcomes in both groups with a greater change percentage in group A (p < 0.05).

CONCLUSIONS

These results indicate that the addition of BE to the CR programs in CHF is effective and is a "patient-centered" approach.

Sensitivity and specificity of different exercise oscillatory ventilation definitions to predict 2-year major adverse cardiovascular outcomes in chronic heart failure patients

BACKGROUND

Exercise oscillatory ventilation (EOV) shows a four-fold greater risk of adverse events. This study aims to analyze the sensitivity and specificity of three EOV diagnostic definitions to predict adverse outcomes at a 2-year follow-up and to compare its EOV prevalence and relations with the patient's profile.

METHODS

Cardiopulmonary exercise tests from 233 heart failure patients were analyzed. Two blinded reviewers used a semiautomated software to identify EOV cases pattern according to the definitions of Ben-Dov, Corrà, and Leite. Data were grouped in EOV-positive or EOV-negative according to each definition. Baseline characteristics, EOV prevalence, relative risk, sensitivity, and specificity to predict 2-years of major adverse cardiovascular outcomes were analyzed.

RESULTS

The Corrà definition led to the best prediction of 2-year major cardiovascular adverse outcomes (HR 2.46 [1.16 to 5.25]; p = 0.019, AUC = 0.618; p = 0.007). EOV prevalence was 17.2%, 17.2%, and 9.4% applying Ben-Dov, Corrà, and Leite definition, respectively. The main clinical differences between EOV-positive and EOV-negative patients were: MECKI score and VE/VCO₂ slope (all definitions), and BNP levels (Ben-Dov and Leite). BNP levels were correlated with amplitude (rho = 0.255; p = 0.033) and cycle length (rho = 0.388; p = 0.002).

CONCLUSION

Corrà definition was the only one that exhibited the capacity to predict major adverse cardiovascular outcomes at a 2-year follow-up. Regardless of its definition, EOV was more often prevalent in patients with a greater MECKI score and VE/VCO₂ slope values.

Exercise Oscillatory Breathing in Heart Failure with reduced ejection fraction: clinical implication

AIM

I) to evaluate the impact of exertional oscillatory ventilation (EOV) in patients with heart failure (HF) with reduced left ventricular ejection fraction (HFrEF) during cardiopulmonary exercise testing (CPET) compared with patients without EOV (N-EOV); II) to identify the influence of EOV persistence (P-EOV) and EOV disappearance (D-EOV) during CPET on the outcomes of mortality and hospitalization in HFrEF patients; and III) to identify further predictors of mortality and hospitalization in patients with P-EOV.

METHODS AND RESULTS

315 stable HFrEF patients underwent CPET and were followed for 35 months. We identified 202 patients N-EOV and 113 patients with EOV. Patients with EOV presented more symptoms (NYHA III: 35% vs. N-EOV 20%, p < 0.05), worse cardiac function (LVEF: 28 ± 6 vs. N-EOV 39 ± 1, p < 0.05), higher minute ventilation/carbon dioxide production (V̇E/V̇CO2 slope: 41 ± 11 vs. N-EOV 37 ± 8, p < 0.05) and a higher rate of deaths (26% vs. N-EOV 6%, p < 0.05) and hospitalization (29% vs. N-EOV 9%, p < 0.05). P-EOV patients had more severe HFrEF (NYHA IV: 23% vs D-EOV: 9%, p < 0.05), had worse cardiac function (LVEF: 24 ± 5 vs. D-EOV: 34 ± 3, p < 0.05) and had lower peak oxygen consumption (V̇O2) (12.0 ± 3.0 vs D-EOV: 13.3 ± 3.0 mlO2.kg-1.min-1, p < 0.05). Among P-EOV, other independent predictors of mortality were V̇E/V̇CO2 slope ≥36 and V̇O2 peak ≤12 mlO2.kg-1.min-1; a V̇E/V̇CO2 slope≥34 was a significant predictor of hospitalization. Kaplan-Meier survival analysis showed that, HFrEF patients with P-EOV had a higher risk of mortality and higher risk of hospitalization (p < 0.05) than patients with D-EOV and N-EOV.

CONCLUSION

In HFrEF patients, EOV persistence during exercise had a strong prognostic role. In P-EOV patients V̇E/V̇CO2 ≥36 and V̇O2 peak ≤12 mlO2.kg-1.min-1, had a further additive negative prognostic role.

Prognostic value of 6-min walk test compared to cardiopulmonary exercise test in patients with severe heart failure

AIMS

The 6-min walk test (6MWT) and cardiopulmonary exercise test (CPET) are both predictive in heart failure (HFrEF). Although 6MWT substitutes for CPET in HFrEF patients, as submaximal testing may be preferable, its prognostic superiority still needs to be verified, particularly in regard to beta blockers (BBs). We aimed to compare the prognostic role of CPET and 6MWT and investigate whether BB therapy influences the predictive value.

METHODS

This is a single-center, retrospective study. Advanced HFrEF patients were followed up for 3 years: events were cardiovascular death or urgent heart transplantation. We analyzed the predictive capacity of CPET and 6MWT in patients, and subdivided according to use of BBs.

RESULTS

In a group of 251 HFrEF patients, we found a correlation between meters and peak VO2 (r2 = 0.94). Over the 3-year follow-up, 74 events were recorded. Both CPET and 6MWT variables were correlated with outcome at univariate analysis (meter and VE/VCO2 slope, peak VO2, VO2 at ventilatory anaerobic threshold, percentage predicted of peak VO2), but only percentage predicted of peak VO2 (pppVO2) was an independent predictor. In 103 HFrEF patients on BBs (23 nonsurvivors), neither pppVO2 nor meter were predictive, while in 148 patients not treated with BB (51 with events) pppVO2 was selected as an independent prognostic parameter (P = 0.001).

CONCLUSIONS

6MWT is a valid alternative to CPET, although the percentage of predicted of peak VO2 emerged as the strongest predictor. Nonetheless, our results suggest that both functional derived parameters are not predictive among those patients treated with BBs. Further studies are necessary to confirm these findings.

Heart Failure with Reduced Ejection Fraction and Prognostic Scales: The Impact of Exercise Modality in Cardiopulmonary Exercise Tests

The cardiopulmonary exercise (CPET) test is an essential tool to determine the severity, prognosis, and need for invasive treatments in heart failure with reduced ejection fraction (HFrEF) but disregards the exercise modality. The present study aimed at analyzing the differences between treadmill and cycle-ergometer exercises. This was a prospective study, involving 65 patients with HfrEF who performed treadmill exercise followed by cycle-ergometer exercise 72 h later. We enrolled 65 patients, aged 58 ± 9 years, with an ejection fraction of 29 ± 9%. Peak VO2 was 20% greater (95% CI: 18−21%; p < 0.000) on the treadmill, and the ventilatory efficiency estimated by the VE/VCO2 slope (32 ± 8 vs. 34 ± 9; p < 0.05). The ventilatory response was greater on the treadmill: maximum ventilation (55 ± 16 vs. 46 ± 11 L/min; p < 0.000) and ventilatory reserve at the maximum effort (28 ± 17 vs. 41 ± 15%; p < 0.000). These values led to a change in the functional class of 23 (51%) patients and ventilatory class of 28 (47%) patients. Differences in the main parameters, including peak VO2 and VE/VCO2, impact prognostic scales and possible advanced treatments; therefore, the results should be interpreted in accordance with the exercise modality.

Exercise oscillatory ventilation during autonomic blockade in young athletes and healthy controls

PURPOSE

Exercise oscillatory ventilation (EOV) is a form of periodic breathing that is associated with a poor prognosis in heart failure patients, but little is known about EOV in other populations. We sought to provide insights into the phenomenon of EOV after it was observed in young healthy subjects, including athletes, after the administration of dual autonomic blockade (DAB).

METHODS

From 29 participants who completed cardiopulmonary exercise testing (CPET) with and without DAB (0.04 mg/kg atropine and 0.2 mg/kg metoprolol), 5 subjects developed EOV (age = 29 ± 5 years; 3/5 were athletes) according to American Heart Association criteria. For each case, we identified 2 non-EOV healthy controls (age = 34.2 ± 8.3; 7/10 were athletes) that were subsequently age- and sex-matched.

RESULTS

No participants had EOV during exercise without DAB. The 5 participants (4 male, 1 female) who demonstrated EOV with DAB had lower mean tidal volume (1.7 ± 0.5 L/min vs. 1.8 ± 0.5 L/min; p = 0.04) compared to participants in the non-EOV group and a decrease in peak tidal volume (2.9 ± 0.6 L/min to 2.2 ± 0.7 L/min; p = 0.004) with DAB. There were few other differences in CPET measures between EOV and non-EOV participants, although the PETCO2 tended to be higher in the EOV group (p = 0.07).

CONCLUSION

EOV can be elucidated in young healthy subjects, including athletes, during cardiopulmonary exercise testing, suggesting that it may not be an ominous sign in all populations.

Novel application of Poincaré analysis to detect and quantify exercise oscillatory ventilation

Objective.Exercise oscillatory ventilation (EOV) is frequently observed in individuals with cardiac disease. Assessment of EOV relies on pattern recognition and this subjectivity and lack of quantification limits the widespread clinical use of EOV as a prognostic marker. Poincaré analysis quantifies the short (SD1) and long-term (SD2) variability of a signal and may provide an alternative means to identify and quantify unstable exercise breathing patterns. This study aimed to determine if Poincaré analysis can distinguish between the breathing patterns of healthy control subjects and individuals being assessed for heart transplantation with and without EOV.Approach.Thirty-nine subjects performed a cardiopulmonary exercise test as part of heart transplant assessment and were subjectively classified into two groups according to the presence of EOV: non-EOV (n = 19) and EOV (n = 20). The control group (n = 24) consisted of healthy adults. Poincaré analysis (SD1 and SD2) was performed for minute ventilation (V̇_E) and tidal volume (VT) normalized to forced vital capacity (V̇_EnandV̇_Tn), and breathing frequency (BF) for breath-by-breath data over the 10-15 ml · min^-1 · kg^-1V̇_O2range.Main results.Poincaré analysis showed similar exercise ventilatory responses between the non-EOV and control group. BF was found to discriminate between subjects with stable and unstable ventilation. BF SD1 was significantly higher in the EOV group compared to the non-EOV (7.9 versus 4.6,p < 0.01) and control (7.9 versus 4.2,p < 0.01) groups. The EOV group had significantly greater BF SD2 compared to the non-EOV (5.7 versus 3.5,p < 0.01) and control (5.7 versus 3.5,p < 0.01) groups.Significance.We demonstrated that this novel application of Poincaré analysis can objectively distinguish and quantify unstable from stable breathing patterns during exercise. In subjects being assessed for heart transplantation the presence of EOV is associated with greater BF variability. Poincaré analysis provides an objective measure to identify and quantify EOV.Summary at a glance.As EOV may indicate abnormal ventilatory control, there is a need for an objective measure to identify and quantify unstable from stable ventilation during exercise. We developed a method of quantifying BF variation by the application of Poincaré analysis and demonstrated higher than normal variability of BF in subjects being assessed for heart transplantation who demonstrated EOV.

Ventilation Dispersion Index as an Objective Evaluation Tool of Exercise Oscillatory Ventilation in Patients With Heart Failure

BACKGROUND

Exercise oscillatory ventilation (EOV) is related to worse prognosis in patients with heart failure (HF). However, its determination is subjective and there is no standard measure to identify it. The aim of the study was to evaluate and characterize the EOV of patients with HF using the ventilation dispersion index (VDI).

METHODS AND RESULTS

Patients underwent cardiopulmonary exercise testing (CPX), EOV was assessed by 2 reviewers and the VDI was calculated. The receiver operator curve analysis was used to assess the ability of the VDI to predict EOV. Pearson's correlation test was performed to determine the relationship between VDI and CPX variables. Forty-three patients with HF underwent CPX and were divided into 2 groups: with a VDI of less than 0.601 and a VDI of 0.601 or greater. An area under the curve of 0.759 was observed in the receiver operator curve analysis between VDI and EOV (P = .008). The VDI showed a significant correlation with the ventilatory CPX variables. According to the cut-off point obtained on the receiver operator curve, patients with a VDI of 0.601 or greater had lower left ventricular ejection fraction and higher values of resting minute ventilation and peak minute ventilation.

CONCLUSIONS

The VDI proved to be a good predictor of EOV in patients with HF.

Safety, Tolerability, and Effects of Sodium Bicarbonate Inhalation in Cystic Fibrosis

BACKGROUND

Among the many consequences of loss of CFTR protein function, a significant reduction of the secretion of bicarbonate (HCO₃^-) in cystic fibrosis (CF) is a major pathogenic feature. Loss of HCO₃^- leads to abnormally low pH and impaired mucus clearance in airways and other exocrine organs, which suggests that NaHCO₃ inhalation may be a low-cost, easily accessible therapy for CF.

OBJECTIVE

To evaluate the safety, tolerability, and effects of inhaled aerosols of NaHCO₃ solutions (4.2% and 8.4%).

METHODS

An experimental, prospective, open-label, pilot, clinical study was conducted with 12 CF volunteer participants over 18 years of age with bronchiectasis and pulmonary functions classified as mildly to severely depressed. Sputum rheology, pH, and microbiology were examined as well as spirometry, exercise performance, quality-of-life assessments, dyspnea, blood count, and venous blood gas levels.

RESULTS

Sputum pH increased immediately after inhalation of NaHCO₃ at each clinical visit and was inversely correlated with rheology when all parameters were evaluated: [G' (elasticity of the mucus) = - 0.241; G″ (viscosity of the mucus) = - 0.287; G* (viscoelasticity of the mucus) = - 0.275]. G* and G' were slightly correlated with peak flow, forced expiratory volume in 1 s (FEV₁), and quality of life; G″ was correlated with quality of life; sputum pH was correlated with oxygen consumption (VO₂) and vitality score in quality of life. No changes were observed in blood count, venous blood gas, respiratory rate, heart rate, peripheral oxygen saturation of hemoglobin (SpO₂), body temperature, or incidence of dyspnea. No adverse events associated with the study were observed.

CONCLUSION

Nebulized NaHCO₃ inhalation appears to be a safe and well tolerated potential therapeutic agent in the management of CF. Nebulized NaHCO₃ inhalation temporarily elevates airway liquid pH and reduces sputum viscosity and viscoelasticity.

Exertional Periodic Breathing in Heart Failure: Mechanisms and Clinical Implications

Periodic breathing (PB) during exercise is a slow, prominent, consistent fluctuation in ventilation and derived parameters that may be persistent for the entire exercise or present only in the early phases of exercise. It is associated with a negative prognosis, particularly if concomitant with PB during sleep. Little is known about exercise-induced PB physiology, but hyperventilation is likely due to an increased sympathetic activity combined with an enhanced stimulation of intrapulmonary, chemoreceptors and metaboreceptors, low cardiac output leading to increased circulatory delay, and cerebrovascular reactivity to CO2, all with have a definite role.

Exercise oscillatory ventilation and prognosis in heart failure patients with reduced and mid-range ejection fraction

AIMS

Exercise oscillatory ventilation (EOV) is a pivotal cardiopulmonary exercise test parameter for the prognostic evaluation of patients with chronic heart failure (HF). It has been described in patients with HF with reduced ejection fraction (<40%, HFrEF) and with HF with preserved ejection fraction (>50%, HFpEF), but no data are available for patients with HF with mid-range ejection fraction (40-49%, HFmrEF). The aim of the study was to evaluate the prognostic role of EOV in HFmrEF patients.

METHODS AND RESULTS

We analysed 1239 patients with HFmrEF and 4482 patients with HFrEF, enrolled in the MECKI score database, with a 2-year follow-up. The study endpoint was the composite of cardiovascular death, urgent heart transplant, and ventricular assist device implantation. We identified EOV in 968 cases (16% and 17% of cases in HFmrEF and HFrEF, respectively). HFrEF EOV+ patients were significantly older, and their parameters suggested a more severe HF than HFrEF EOV- patients. A similar behaviour was found in HFmrEF EOV+ vs. EOV- patients. Kaplan-Meier analysis, irrespective of ejection fraction, showed that EOV is associated with a worse survival, and that patients with HFrEF and HFmrEF EOV+ had a significantly worse outcome than the EOV- of the same ejection fraction groups. EOV-associated survival differences in HFmrEF patients started after 18 months of follow-up.

CONCLUSION

Exercise oscillatory ventilation has a similar prevalence and ominous prognostic value in both HFmrEF and HFrEF patients, indicating a group of patients in need of a more intensive follow-up and a more aggressive therapy. In HFmrEF, the survival curves between EOV+ and EOV- patients diverged only after 18 months.

Relationship Between Exercise Oscillatory Ventilation Loop and Prognosis of Heart Failure

BACKGROUND

The cardiopulmonary exercise test (CPX) is a tool for evaluating disease severity and limitations in activities of daily living in patients with cardiac disorders. However, few studies have evaluated the association between exercise oscillatory ventilation (EOV) severity and prognosis in heart failure (HF) patients with EOV. EOV severity can be evaluated by detecting endtidal CO2pressure (PETCO2, an indicator of the arterial partial pressure of CO2(PaCO2)) and minute ventilation, which is a reflection of the respiratory response to elevated CO2. We hypothesized that the magnitude of EOV severity can predict the severity and prognosis of cardiac disorders and aimed to validate this hypothesis.

METHODS AND RESULTS

In total, 2,043 patients who underwent symptom-limited maximal CPX between 2010 and 2016 were evaluated. We enrolled 70 patients who had HF with reduced ejection fraction (HFrEF) and EOV. The endpoint was cardiovascular death. During a median follow-up of 4.3 years, 34 participants died (48%). Those who died showed significantly larger EOV loop size and lower hemoglobin (Hb) levels than those who survived (17.3±7.0 cm2vs. 12.8±6.1 cm2, P<0.001; 12.2±1.2 g/dL vs. 13.2±2.9 g/dL, P=0.004). Cox regression analyses revealed Hb levels and EOV loop size as independent predictors of cardiovascular death in HFrEF patients with EOV.

CONCLUSIONS

EOV loop size was associated with cardiovascular death of HFrEF patients with EOV.

Association of Oscillatory Ventilation during Cardiopulmonary Test to Clinical and Functional Variables of Chronic Heart Failure Patients

Objective

The aim of this study is to characterize the presence of exercise oscillatory ventilation (EOV) and to relate it with other cardiopulmonary exercise test (CET) responses and clinical variables.

Methods

Forty-six male patients (age: 53.1±13.6 years old; left ventricular ejection fraction [LVEF]: 30±8%) with heart failure were recruited to perform a maximal CET and to correlate the CET responses with clinical variables. The EOV was obtained according to Leite et al. criteria and VE/VCO₂ > 34 and peak VO₂ < 14 ml/kg/min were used to assess patients' severity.

Results

The EOV was observed in 16 of 24 patients who performed the CET, as well as VE/VCO₂ > 34 and peak VO₂ < 14 ml/kg/min in 14 and 10 patients, respectively. There was no difference in clinical and CET variables of the patients who presented EOV in CET when compared to non-EOV patients. Also, there was no difference in CET and clinical variables when comparing patients who presented EOV and had a VE/VCO₂ slope > 34 to patients who just had one of these responses either.

Conclusion

The present study showed that there was an incidence of patients with EOV and lower peak VO₂ and higher VE/VCO₂ slope values, but they showed no difference on other prognostic variables. As well, there was no influence of the presence of EOV on other parameters of CET in this population, suggesting that this variable may be an independent marker of worst prognosis in HF patients.

Exercise Oscillatory Ventilation: Interreviewer Agreement and a Novel Determination

INTRODUCTION

Determination of exercise oscillatory ventilation (EOV) is subjective, and the interreviewer agreement has not been reported. The purposes of this study were, among patients with heart failure (HF), as follows: 1) to determine the interreviewer agreement for EOV and 2) to describe a novel, objective, and quantifiable measure of EOV.

METHODS

This was a secondary analysis of the HEART Camp: Promoting Adherence to Exercise in Patients with Heart Failure study. EOV was determined through a blinded review by six individuals on the basis of their interpretation of the EOV literature. Interreviewer agreement was assessed using Fleiss kappa (κ). Final determination of EOV was based on agreement by four of the six reviewers. A new measure (ventilation dispersion index; VDI) was calculated for each test, and its ability to predict EOV was assessed with the receiver operator characteristics curve.

RESULTS

Among 243 patients with HF (age, 60 ± 12 yr; 45% women), the interreviewer agreement for EOV was fair (κ = 0.303) with 10-s discrete data averages and significantly better, but only moderate (κ = 0.429) with 30-s rolling data averages. Prevalence rates of positive and indeterminate EOVs were 18% and 30% with the 10-s discrete averages and 14% and 13% with the 30-s rolling averages, respectively. VDI was strongly associated with EOV, with areas under the receiver operator characteristics curve of 0.852 to 0.890.

CONCLUSIONS

Interreviewer agreement for EOV in patients with HF is fair to moderate, which can negatively affect risk stratification. VDI has strong predictive validity with EOV; as such, it might be a useful measure of prognosis in patients with HF.

Prevalence of exertional oscillatory ventilation in continuous-flow left ventricular assist device recipients

Background

Exercise oscillatory ventilation is an ominous outcome sign in heart failure due to reduced left ventricular ejection fraction; currently, the prevalence of exercise oscillatory ventilation is unknown in left ventricular assist device recipients.

Methods

We studied cardiopulmonary exercise testing in heart failure due to reduced left ventricular ejection fraction or left ventricular assist device patients and exercise oscillatory ventilation was defined according to Kremser's criteria.

Results

The occurrence of exercise oscillatory ventilation was similar in either heart failure due to reduced left ventricular ejection fraction (192 patients, 8%) or left ventricular assist device patients (85 recipients, 10%), even though the mean peak oxygen consumption and elevated ventilatory response to exercise slope was lower and higher in left ventricular assist device recipients, respectively, but the occurrence of exercise oscillatory ventilation was comparable among heart failure patients due to reduced left ventricular ejection fraction and left ventricular assist device, if those with impaired exercise capacity were considered. Of note, left ventricular assist device recipients with exercise oscillatory ventilation had a higher end-diastolic left ventricular volume and systolic pulmonary artery pressure at rest.

Conclusions

Using the largest cohort of left ventricular assist device patients performing cardiopulmonary exercise testing, we demonstrated that the occurrence of exercise oscillatory ventilation is similar in heart failure due to reduced left ventricular ejection fraction and left ventricular assist device patients. Recipients with exercise oscillatory ventilation might have haemodynamic and ventilatory dysfunction during exercise, but other factors could play a role, i.e. the duration and severity of heart failure before left ventricular assist device implantation together with the coexistence of morbidity.

Association between right ventricle two- and three-dimensional echocardiography and exercise capacity in patients with reduced left ventricular ejection fraction

Introduction

Echocardiography represents the most commonly performed noninvasive cardiac imaging test for patients with heart failure (HF). The aim of this study was to assess the relationship between exercise capacity parameters (peak oxygen consumption (VO₂) and the minute ventilation-carbon dioxide production relationship (VE/VCO₂)), two-dimensional speckle-tracking echocardiography (2D-STE) and three-dimensional echocardiography (3DE) imaging of right ventricular (RV) function in HF patients with reduced ejection fraction (EF).

Material and methods

This cross-sectional study included 54 patients with diagnosed ischemic LV systolic dysfunction (HF with reduced EF <40%) divided in subgroups based on the proposed values of the analyzed cardiopulmonary exercise testing (CPET) variables: VO₂ peak ≤ 15 ml/kg/min, VO₂ peak > 15 ml/kg/min, VE/VCO₂ slope < 36 and VE/VCO₂ slope ≥ 36. All patients underwent a physical examination, laboratory testing, conventional echocardiography, 2D-STE, 3DE, and CPET.

Results

RV fractional area change (FAC), 2D RV global longitudinal strain (GLS), 3D RV EF were significantly decreased, and RV basal diameter (BD), systolic pulmonary artery pressure (SPAP), tricuspid annular plane systolic excursion (TAPSE), ratio between tricuspid flow and tissue Doppler derived e’ of the lateral tricuspid annulus (TV E/e’) were significantly increased in the subgroups of subjects with a worse VO₂ peak and VE/VCO₂ slope values. There was a significant positive correlation between the peak VO₂ values and TAPSE, 2D RV GLS, 3D RV SV, and 3D RV EF as well as a significantly inverse correlation with VE/VCO₂ slope.

Conclusions

The observed significant correlation between the examined parameters suggests that 2D RV GLS and 3D RV EF, SV are associated with exercise capacity in patients with reduced HF.

Periodic Breathing during Incremental Exercise

Periodic breathing during incremental cardiopulmonary exercise testing is a regularly recurring waxing and waning of tidal volume due to oscillations in central respiratory drive. Periodic breathing is a sign of respiratory control system instability, which may occur at rest or during exercise. The possible mechanisms responsible for exertional periodic breathing might be related to any instability of the ventilatory regulation caused by: (1) increased circulatory delay (i.e., circulation time from the lung to the brain and chemoreceptors due to reduced cardiac index leading to delay in information transfer), (2) increase in controller gain (i.e., increased central and peripheral chemoreceptor sensitivity to arterial partial pressure of oxygen and of carbon dioxide), or (3) reduction in system damping (i.e., baroreflex impairment). Periodic breathing during exercise is observed in several cardiovascular disease populations, but it is a particularly frequent phenomenon in heart failure due to systolic dysfunction. The detection of exertional periodic breathing is linked to outcome and heralds worse prognosis in heart failure, independently of the criteria adopted for its definition. In small heart failure cohorts, exertional periodic breathing has been abolished with several dedicated interventions, but results have not yet been confirmed. Accordingly, further studies are needed to define the role of visceral feedbacks in determining periodic breathing during exercise as well as to look for specific tools for preventing/treating its occurrence in heart failure.

Exercise testing in heart failure: a contemporary discussion in an era of novel diagnostic techniques and biomarkers

PURPOSE OF REVIEW

The purpose of this review is to highlight recent advances in the field of exercise testing for patients with heart failure.

RECENT FINDINGS

The importance of assessment of cardiorespiratory fitness (CRF) and exercise testing in heart failure is highlighted in the consensus recommendation of the American Heart Association. Contemporary studies have validated the independent and incremental strength of CRF metrics in patients with heart failure and coronary artery disease. The use of respiratory gas analysis and imaging or hemodynamics during physical exercise is feasible and results in high prognostic utility across the continuum of heart failure. Understanding how CRF metrics complement existing and novel biomarkers and risk scores is an emerging subject of scientific inquiry.

SUMMARY

In the current era of personalized medicine, integrating CRF, imaging and circulating biomarkers will allow us to further develop individualized strategies for improving outcome in patients with heart failure.

Exercise training improves characteristics of exercise oscillatory ventilation in chronic heart failure

Background Exercise oscillatory ventilation in chronic heart failure has been suggested as a factor related to adverse cardiac events, aggravated prognosis and higher mortality. Exercise training is well known to affect exercise capacity and mechanisms of pathophysiology beneficially in chronic heart failure. Little is known, however, about the exercise training effects on characteristics of exercise oscillatory ventilation in chronic heart failure patients. Design and methods Twenty (out of 38) stable chronic heart failure patients exhibited exercise oscillatory ventilation (age 54 ± 11 years, peak oxygen uptake 15.0 ± 5.0 ml/kg per minute). Patients attended 36 sessions of high intensity interval exercise. All patients underwent cardiopulmonary exercise testing before and after the programme. Assessment of exercise oscillatory ventilation was based on the amplitude of cyclic fluctuations in breathing during rest and exercise. All values are mean ± SD. Results Exercise training reduced ( P < 0.05) the percentage of exercise oscillatory ventilation duration (79.0 ± 13.0 to 50.0 ± 25.0%), while average amplitude (5.2 ± 2.0 to 4.9 ± 1.6 L/minute) and length (44.0 ± 10.9 to 41.0 ± 6.7 seconds) did not change ( P > 0.05). Exercise oscillatory ventilation patients also increased exercise capacity ( P < 0.05). Conclusions A rehabilitation programme based on high intensity interval training improved exercise oscillatory ventilation observed in chronic heart failure patients, as well as cardiopulmonary efficiency and functional capacity.

Comparing exercise training modalities in heart failure: A systematic review and meta-analysis

Exercise training (ET) is suggested to improve exercise capacity, prognosis, quality of life (QOL) and functional modifications of the heart in patients with heart failure (HF). However, it is not clear which modality is best. In order to assess the effectiveness of different ET modalities on prognostic cardiopulmonary exercise test (CPET) parameters, QOL and left ventricular remodeling, a systematic review and meta-analysis was performed. Randomized clinical trials (RCTs) were selected in three databases. The primary outcome data were peak oxygen uptake, ventilation over carbon dioxide slope, oxygen uptake efficiency slope, exercise oscillatory ventilation, rest and peak pulmonary end-tidal CO2. Secondary variables were QOL, left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter (LVEDD). Twenty RCTs (n=811) met the a priori stated inclusion criteria. Studies were categorized into four different groups: "interval training (IT1) versus combined interval and strength training (IT1S)" (n=156), "continuous training (CT1) versus combined continuous and strength training (CT1S)" (n=130), "interval training (IT2) versus continuous training (CT2)" (n=501) and "continuous training (CT3) versus strength training (S3)" (n=24). No significant random effects of exercise modality were revealed assessing the CPET parameters. There was a significant improvement in QOL applying CT1S (P<0.001). Comparing IT2 with CT2, LVEDD and LVEF were significantly improved favoring IT2 (P<0.001). There is some evidence to support that interval training is more effective to improve LVEF and LVEDD. The fact that patients with HF are actively involved in any kind of ET program seems sufficient to improve the prognosis, QOL and anatomic function.

Cardiopulmonary Exercise Testing in Heart Failure

Exercise intolerance, indicated by dyspnea and fatigue during exertion, is a cardinal manifestation of heart failure (HF). Cardiopulmonary exercise testing (CPET) precisely defines maximum exercise capacity through measurement of peak oxygen uptake (VO2). Peak VO2 values have a critical role in informing patient selection for advanced HF interventions such as heart transplantation and ventricular assist devices. Oxygen uptake and ventilatory patterns obtained during the submaximal portion of CPET are also valuable to recognize because of their ease of ascertainment during low-level exercise, relevance to ability to perform activities of daily living, independence from volitional effort, and strong relationship to prognosis in HF. The ability of peak VO2 and other CPET variables to be measured reproducibly and to accurately reflect HF severity is increasingly recognized and endorsed by scientific statements. Integration of CPET with invasive hemodynamic monitoring and cardiac imaging during exercise provides comprehensive characterization of multisystem reserve capacity that can inform prognosis and the need for cardiac interventions. Here, we review both practical aspects of conducting CPETs in patients with HF for clinical and research purposes as well as interpretation of gas exchange patterns across the spectrum of preclinical HF to advanced HF.

An overview of the applied definitions and diagnostic methods to assess exercise oscillatory ventilation--a systematic review

The variable "exercise oscillatory ventilation" (EOV), assessed during cardiopulmonary exercise test (CPET), recently became a fundamental prognostic parameter in patients with heart failure. In literature, various definitions are suggested, but an uniformly accepted description to identify EOV still lacks. We performed a systematic review of the literature in order to determine the different definitions and diagnostic techniques to assess EOV. A systematic search strategy was established and executed in seven databases (PubMed, Google Scholar, Cochrane Clinical Trials, Science Direct, Pedro, Web Of Science library and Medline (Ovid)) resulting in 605 citations after de-duplication. Full-text articles (n=124) were assessed for eligibility, resulting in 75 citations. The review accounted 17,440 patients of whom 4,638 subjects presented EOV. Seven studies described EOV in a non-heart failure population accounting 168 EOV subjects. The definitions could be categorized in nine subdivisions of which four (n=43) referred to an original description. The other subdivisions were combinations of the original definitions (n=11), quantifications (n=4), computational (n=3), vaguely described (n=8) or not defined (n=6). Symptom limited maximal exercise tests were conducted to assess EOV, however the modes, protocols, software and data sampling were divers. Heterogeneity in the numerous definitions to identify EOV and the vaguely described assessment methods are hindering the evolution to a standardized uniformly accepted definition and technique to identify this abnormal breathing pattern. Unity in definition and international adopted assessment is warranted to strengthen its validity as a prognostic marker and could promote communication. It may facilitate clinical trials on pathophysiology and origin of EOV.