Different Determinants of Ventilatory Inefficiency at Different Stages of Reduced Ejection Fraction Chronic Heart Failure Natural History

The Usefulness of Soluble ST2 Concentration in Heart Failure with Reduced Ejection Fraction to Predict Severe Impairment in Exercise Capacity Assessed in Cardiopulmonary Exercise Testing

Background/Objectives: Heart failure (HF) constitutes a complex clinical syndrome that is highly prevalent worldwide, comprises a serious prognosis, and results in a reduced quality of life. Exercise capacity is one of the most significant parameters involved in the prognosis in HF patients. Our objective was to evaluate the relationship between the selected cardiopulmonary exercise testing (CPET) parameters and the concentration of novel biomarker sST2 in a group of patients with heart failure with reduced ejection fraction (HFrEF). Methods: A group of 135 patients with HFrEF was enrolled in this prospective cohort study. Patients were in the stable phase of the disease in the prior 4 weeks and received optimal medical treatment. Clinical and biochemical parameters were investigated. All patients performed maximal CPET. Results: The mean (SD) concentration of sST2 was 45.5 ± 39.2 ng/mL. Based on the CPET results, the cut-off value (52.377 ng/mL) was established, optimal for the discrimination of relative peakVO2 < 12 mL/kg/min. Patients were divided into two groups according to sST2 cut-off values determined with an ROC curve (AUC 0.692, 95% CI: 0.567-0.816). The mean relative peakVO2 in patients with higher sST2 was 14.5 ± 4.6 mL/kg/min, while in the second group, it was 17.6 ± 5.2 (p = 0.002). In the sST2 ≥ 52.377 ng/mL group, 55.6% of patients achieved VO2 < 50%. Subjects with lower sST2 values obtained higher values of PETCO2 (p < 0.001) and higher values of pulse O2 (p = 0.01). VE/VCO2slope (p = 0.002) was higher in patients with increased sST2 concentration. Conclusions: The concentration of sST2 protein is substantially associated with the clinical severity of heart failure with reduced left ventricular ejection fraction assessed by functional capacity through CPET.

Gas exchange efficiency slopes to assess exercise tolerance in chronic obstructive pulmonary disease

BACKGROUND

In patients with chronic obstructive pulmonary disease (COPD), the clinical use of the minute ventilation-carbon dioxide production ([Formula: see text]E-[Formula: see text]CO2) slope has been reported as a measure of exercise efficiency, but the oxygen uptake efficiency slope (OUES), i.e., the slope of oxygen uptake ([Formula: see text]O2) versus the logarithmically transformed [Formula: see text]E, has rarely been reported.

METHODS

We hypothesized that the [Formula: see text]E-[Formula: see text]CO2 slope is more useful than OUES in clinical use for the pathophysiological evaluation of COPD. Then, we investigated the cardiopulmonary exercise testing parameters affecting each of these slopes in 122 patients with all Global Initiative for Chronic Obstructive Lung Disease (GOLD) COPD grades selected from our database.

RESULTS

Compared with the GOLD I-II group (n = 51), peak [Formula: see text]O2 (p < 0.0001), OUES (p = 0.0161), [Formula: see text]E at peak exercise (p < 0.0001), and percutaneous oxygen saturation (SpO2) at peak exercise (p = 0.0004) were significantly lower in the GOLD III-IV group (n = 71). The GOLD III-IV group was divided into two groups by the exertional decrease in SpO2 from rest to peak exercise: 3% or less (the non-desaturation group: n = 23), or greater than 3% (the desaturation group: n = 48). OUES correlated only weakly with peak [Formula: see text]O2, [Formula: see text]E at peak exercise, and the difference between inspired and expired mean O2 concentrations (ΔFO2) at peak exercise, i.e., an indicator of oxygen consumption ability throughout the body, in the GOLD III-IV group with exertional hypoxemia. In contrast, the [Formula: see text]E-[Formula: see text]CO2 slope was significantly correlated with ΔFO2 at peak exercise, regardless of the COPD grade and exertional desaturation. Across all COPD stages, there was no correlation between the [Formula: see text]E-[Formula: see text]CO2 slope and [Formula: see text]E at peak exercise, and stepwise analysis identified peak [Formula: see text]O2 (p = 0.0345) and ΔFO2 (p < 0.0001) as variables with a greater effect on the [Formula: see text]E-[Formula: see text]CO2 slope.

CONCLUSIONS

The OUES may be less useful in advanced COPD with exertional hypoxemia. The [Formula: see text]E-[Formula: see text]CO2 slope, which is independent of [Formula: see text]E, focuses on oxygen consumption ability and exercise tolerance in COPD, regardless of the exertional hypoxemia level and COPD grade. Therefore, the [Formula: see text]E-[Formula: see text]CO2 slope might be useful in establishing or evaluating tailor-made therapies for individual patient's pathologies in COPD as an indicator focusing on oxygen consumption ability.

Time to negative conversion and cardiopulmonary performance in athletes with COVID-19

Athletes with longer time to negative conversion for COVID-19 do not present reduction of exercise capacity. However, respiratory and ventilatory parameters are modified. https://bit.ly/3TMdrFL.

Ventilatory efficiency in post-COVID-19 athletes

Limitation in exercise capacity has not been described in athletes affected by SARS-CoV-2 infection. However, patients who have recovered from COVID-19 without cardiopulmonary impairment show exaggerated ventilatory response during exercise. Therefore, we aimed to evaluate the ventilatory efficiency (VEf) in competitive athletes recovered from COVID-19 and to characterize the ventilation versus carbon dioxide relationship (VE/VCO2 ) slope in this population. Thirty-seven competitive athletes with COVID-19 were recruited for this study. All participants underwent spirometry, echocardiography, and cardiopulmonary exercise testing (CPET). z-FVC values and end-title pressure of CO2 (PET CO2 ) were lower in the third tertile compared with the first tertile: -0.753 ± 0.473 vs. 0.037 ± 0.911, p = 0.05; 42.2 ± 2.7 vs. 37.1 ± 2.5 mmHg, p < 0.01. VE/VCO2 slope was significantly correlated to maximal VCO2 /VE and maximal VO2 /VE: coefficient = -0.5 R2  = 0.58, p < 0.0001 and coefficient = -0.3 R2  = 0.16, p = 0.008. Competitive athletes affected by SARS-CoV-2 infection, without cardio-respiratory disease sequel, may present ventilatory inefficiency (ViE), without exercise capacity limitation. FVC is higher in athletes with better ventilatory performance during exercise, and increased VE/VCO2 slope is inversely correlated to max VCO2 /VE and max VO2 /VE.

The relationship between homocysteine and cardiopulmonary exercise testing in patients with acute coronary syndrome after percutaneous coronary intervention

OBJECTIVE

The purpose of this study was to investigate the relationship between homocysteine (Hcy) levels and cardiopulmonary exercise testing (CPET) in patients with acute coronary syndrome (ACS) after percutaneous coronary intervention (PCI). We also explored the relationship between Hcy levels and cardiac ultrasonography.

METHODS

This study comprised 261 patients with ACS who underwent coronary angiography and PCI at Yulin First Hospital from January 2020 to June 2021. All subjects completed basic data collection, laboratory examination, CPET and cardiac ultrasonography. The CPET includes the peak oxygen uptake (peak VO₂), anaerobic threshold (AT), metabolic equivalents (METs), exercise load (load), oxygen pulse (O₂ pulse), end-tidal CO₂ partial pressure (PETCO₂), ventilatory equivalents for carbon dioxide (VE/VCO₂) and Oxygen uptake efficiency (OUES). Cardiac ultrasonography was used to evaluate the left ventricular end diastolic diameter (LVEDD), interventricular septal thickness (IVST), left ventricular posterior wall thickness (LVPWT) and left ventricular ejection fraction (LVEF). A serum Hcy level ≥ 15 µmol/L was defined as hyperhomocysteinemia (HHcy). The patients were divided into the Hcy < 15 µmol/L group (n = 189) and the Hcy ≥ 15 µmol/L group (n = 72).

RESULTS

The average age of the participating patients was 58.9 ± 10.1 years. The majority of participants were male (86.6%). The CPET indices of METs, load, VO₂/kg, and PETCO₂ were significantly decreased in the Hcy ≥ 15 µmol/L group compared with the Hcy < 15 µmol/L group. Additionally, the CPET index of the VE/VCO₂ slope and the cardiac ultrasonography indices of IVST and LVPWT were significantly increased in the Hcy ≥ 15 µmol/L group compared with the Hcy < 15 µmol/L group. These differences were statistically significant (P < 0.05). Correlation analysis showed that Hcy levels were negatively correlated with METs, VO₂/kg and PETCO₂ and positively correlated with the VE/VCO₂ slope (P < 0.05). Partial correlation analysis showed that Hcy levels were negatively correlated with METs and VO₂/kg in the AT state. The correlation coefficients were - 0.172 and - 0.172, respectively (P < 0.05). Hcy levels were negatively correlated with METs, VO₂/kg and PETCO₂ in the peak state. The correlation coefficients were - 0.177, -0.153 and - 0.129, respectively (P < 0.05). After further adjustment for confounders, multiple linear regression analysis showed that Hcy levels were negatively correlated with METs and VO₂/kg in the AT state and peak state. The standardized regression coefficients were - 0.035, -0.122, -0.048 and - 0.128, respectively (P < 0.05). Correlation analysis showed that Hcy levels were positively correlated with the IVST and LVPWT (P < 0.05), but after adjusting for confounding factors, partial correlation analysis showed that there was no correlation between them.

CONCLUSION

A high Hcy level is associated with lower METs and VO₂/kg and worse cardiopulmonary function in patients with ACS after PCI.

Determinants of minute ventilation-carbon dioxide production relationship in Chagas cardiomyopathy

INTRODUCTION:

The minute ventilation-carbon dioxide production relationship (VE/VCO₂ slope) is among the main prognostic factors of Chagas cardiomyopathy whose determinants remain unknown.

METHODS:

Seventy-eight patients with Chagas cardiomyopathy were evaluated using clinical assessment, cardiopulmonary exercise test, echocardiography, and International Physical Activity Questionnaire.

RESULTS:

Age, functional class, International Physical Activity Questionnaire score, and dilated cardiomyopathy with systolic dysfunction were independent determinants of VE/VCO₂ slope, and these variables explained 63% of its variance.

CONCLUSIONS:

The VE/VCO₂ slope was related to age, functional class, physical activity level, and dilated cardiomyopathy with systolic dysfunction in patients with Chagas cardiomyopathy.

Minute ventilation/carbon dioxide production in chronic heart failure

In chronic heart failure, minute ventilation (V'_E) for a given carbon dioxide production (V'_CO2 ) might be abnormally high during exercise due to increased dead space ventilation, lung stiffness, chemo- and metaboreflex sensitivity, early metabolic acidosis and abnormal pulmonary haemodynamics. The V'_E versus V'_CO2 relationship, analysed either as ratio or as slope, enables us to evaluate the causes and entity of the V'_E/perfusion mismatch. Moreover, the V'_E axis intercept, i.e. when V'_CO2 is extrapolated to 0, embeds information on exercise-induced dead space changes, while the analysis of end-tidal and arterial CO₂ pressures provides knowledge about reflex activities. The V'_E versus V'_CO2 relationship has a relevant prognostic power either alone or, better, when included within prognostic scores. The V'_E versus V'_CO2 slope is reported as an absolute number with a recognised cut-off prognostic value of 35, except for specific diseases such as hypertrophic cardiomyopathy and idiopathic cardiomyopathy, where a lower cut-off has been suggested. However, nowadays, it is more appropriate to report V'_E versus V'_CO2 slope as percentage of the predicted value, due to age and gender interferences. Relevant attention is needed in V'_E versus V'_CO2 analysis in the presence of heart failure comorbidities. Finally, V'_E versus V'_CO2 abnormalities are relevant targets for treatment in heart failure.

Respiratory muscle weakness increases dead-space ventilation ratio aggravating ventilation-perfusion mismatch during exercise in patients with chronic heart failure

BACKGROUND AND OBJECTIVE

Respiratory muscle weakness causes fatigue in these muscles during exercise and thereby increases dead-space ventilation ratio with decreased tidal volume. However, it remains unclear whether respiratory muscle weakness aggravates ventilation-perfusion mismatch through the increased dead-space ventilation ratio. In ventilation-perfusion mismatch during exercise, minute ventilation versus carbon dioxide production (VE/VCO₂ ) slope > 34 is an indicator of poor prognosis in patients with chronic heart failure (CHF). We examined the relationship of respiratory muscle weakness with dead-space ventilation ratio and ventilation-perfusion mismatch during exercise and clarified whether respiratory muscle weakness was a clinical predictor of VE/VCO₂ slope > 34 in patients with CHF.

METHODS

Maximal inspiratory pressure (PI_max ) was measured as respiratory muscle strength 2 months after hospital discharge in 256 compensated patients with CHF. During cardiopulmonary exercise test, we assessed minute dead-space ventilation versus VE (VD/VE ratio) as dead-space ventilation ratio and VE/VCO₂ slope as ventilation-perfusion mismatch. Patients were divided into low, moderate and high PI_max groups based on the PI_max tertile. We investigated determinants of VE/VCO₂ slope > 34 among these groups.

RESULTS

The low PI_max group showed significantly higher VD/VE ratios at 50% of peak workload and at peak workload and higher VE/VCO₂ slope than the other two groups (P < 0.001, respectively). PI_max was a significant independent determinant of VE/VCO₂ slope > 34 (odds ratio (OR): 0.67, 95% CI: 0.54-0.82) with area under the receiver operating characteristic curve of 0.812 (95% CI: 0.750-0.874).

CONCLUSION

Respiratory muscle weakness was associated with an increased dead-space ventilation ratio aggravating ventilation-perfusion mismatch during exercise in patients with CHF.