Usefulness of ventilatory inefficiency in predicting prognosis across the heart failure spectrum

Exercise Testing in Patients with Pulmonary Hypertension

Pulmonary hypertension (PH), defined by a mean pulmonary artery pressure of >20 mm Hg, often presents with non-specific symptoms such as dyspnea and exercise intolerance, making it difficult to diagnose early before the onset of right heart dysfunction. Therefore, exercise testing can be of great utility for clinicians who are evaluating patients with an unclear etiology of exercise intolerance by helping identify the underlying mechanisms of their disease. The presence of PH is associated with adverse clinical outcomes, with distinct differences and patterns in the cardiovascular and ventilatory responses to exercise across various PH phenotypes. We discuss the role of exercise-invasive hemodynamic testing, cardiopulmonary exercise testing, and exercise stress echocardiography modalities across the spectrum of PH.

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.

Ventilatory Efficiency Is Reduced in People With Hypertension During Exercise

Background An elevated ventilatory efficiency slope during exercise (minute ventilation/volume of expired CO2; VE/VCO2 slope) is a strong prognostic indicator in heart failure. It is elevated in people with heart failure with preserved ejection, many of whom have hypertension. However, whether the VE/VCO2 slope is also elevated in people with primary hypertension versus normotensive individuals is unknown. We hypothesize that there is a spectrum of ventilatory inefficiency in cardiovascular disease, reflecting an increasingly abnormal physiological response to exercise. The aim of this study was to evaluate the VE/VCO2 slope in patients with hypertension compared with age-, peak oxygen consumption-, and sex-matched healthy subjects. Methods and Results Ramped cardiovascular pulmonary exercise tests to peak oxygen consumption were completed on a bike ergometer in 55 patients with primary hypertension and 24 normotensive controls. The VE/VCO2 slope was assessed from the onset of exercise to peak oxygen consumption. Data were compared using unpaired Student t test. Age (mean±SD, 66±6 versus 64±6 years; P=0.18), body mass index (25.4±3.5 versus 24±2.4 kg/m2; P=0.13), and peak oxygen consumption (23.2±6.6 versus 24±7.3 mL/min per kg; P=0.64) were similar between groups. The VE/VCO2 slope was elevated in the hypertensive group versus controls (31.8±4.5 versus 28.4±3.4; P=0.002). Only 27% of the hypertensive group were classified as having a normal VE/VCO2 slope (20-30) versus 71% in the control group. Conclusions Ventilatory efficiency is impaired people with hypertension without a diagnosis of heart failure versus normotensive individuals. Future research needs to establish whether those patients with hypertension with elevated VE/VCO2 slopes are at risk of developing future heart failure.

Functional assessment based on cardiopulmonary exercise testing in mild heart failure: A multicentre study

AIMS

In this multicentre study, we compared cardio-pulmonary exercise test (CPET) parameters between heart failure (HF) patients classified as New York Heart Association (NYHA) class I and II to assess NYHA performance and prognostic role in mild HF.

METHODS AND RESULTS

We included consecutive HF patients in NYHA class I or II who underwent CPET in three Brazilian centres. We analysed the overlap between kernel density estimations for the per cent-predicted peak oxygen consumption (VO2 ), minute ventilation/carbon dioxide production (VE/VCO2 ) slope, and oxygen uptake efficiency slope (OUES) by NYHA class. Area under the receiver-operating characteristic curve (AUC) was used to assess the capacity of per cent-predicted peak VO2 to discriminate between NYHA class I and II. For prognostication, time to all-cause death was used to produce Kaplan-Meier estimates. Of 688 patients included in this study, 42% were classified as NYHA I and 58% as NYHA II, 55% were men, and mean age was 56 years. Median global per cent-predicted peak VO2 was 66.8% (IQR 56-80), VE/VCO2 slope was 36.9 (31.6-43.3), and mean OUES was 1.51 (±0.59). Kernel density overlap between NYHA class I and II was 86% for per cent-predicted peak VO2 , 89% for VE/VCO2 slope, and 84% for OUES. Receiving-operating curve analysis showed a significant, albeit limited performance of per cent-predicted peak VO2 alone to discriminate between NYHA class I vs. II (AUC 0.55, 95% CI 0.51-0.59, P = 0.005). Model accuracy for probability of being classified as NYHA class I (vs. NYHA class II) across the spectrum of the per cent-predicted peak VO2 was limited, with an absolute probability increment of 13% when per cent-predicted peak VO2 increased from 50% to 100%. Overall mortality in NYHA class I and II was not significantly different (P = 0.41), whereas NYHA class III patients displayed a distinctively higher death rate (P < 0.001).

CONCLUSIONS

Patients with chronic HF classified as NYHA I overlapped substantially with those classified as NYHA II in objective physiological measures and prognosis. NYHA classification may represent a poor discriminator of cardiopulmonary capacity in patients with mild HF.

Effects of cardiac rehabilitation on cardiopulmonary test parameters in heart failure: A real world experience

Background

Cardio-Pulmonary Exercise Test (CPET) is the gold standard for evaluation of patients with heart failure (HF); however, its use is limited in everyday practice. We analyzed the use of CPET for HF management in the real world.

Methods

From 2009 to 2022, 341 patients with HF underwent 12-16 weeks of rehabilitation in our Centre. We present data from 203 patients (60%), excluding those unable to perform CPET, those with anaemia and severe pulmonary disease. Before and after rehabilitation, we performed CPET, blood tests and echocardiography, tailoring individual physical training to the results of baseline test. The following variables were considered: peak Respiratory Equivalent Ratio (RER), peakVO₂ (ml/Kg/min), VO₂ at aerobic threshold (VO₂AT,% maximal), VE/VCO₂ slope, P_(ET)CO₂, VO₂ /Work ratio (ΔVO₂/ΔWork).

Results

Rehabilitation improved peak VO₂, pulse O₂, VO₂ AT and ΔVO₂/ΔWork in all patients by about 13% (p < 0.01). Most patients (126, 62%) showed a reduced left ventricular ejection fraction (HFrEF), but rehabilitation was effective also in patients with mildly reduced (HFmrEF: n = 55, 27%) or preserved ejection fraction (HFpEF: n = 22, 11%).

Conclusions

Rehabilitation in patients with heart failure induces a significant recovery of cardiorespiratory performance easily assessed by CPET, that is applicable to the majority of them and should be used routinely in the programming and evaluating of cardiac rehabilitation programs.

The prognostic value of cardiopulmonary exercise testing and HFA-PEFF in patients with unexplained dyspnea and preserved left ventricular ejection fraction

BACKGROUND

HFA-PEFF and cardiopulmonary exercise testing (CPET) are comprehensive diagnostic tools for heart failure with preserved ejection fraction (HFpEF). We aimed to investigate the incremental prognostic value of CPET for the HFA-PEFF score among patients with unexplained dyspnea with preserved ejection fraction (EF).

METHODS

Consecutive patients with dyspnea and preserved EF (n = 292) were enrolled between August 2019 and July 2021. All patients underwent CPET and comprehensive echocardiography, including two-dimensional speckle tracking echocardiography in the left ventricle, left atrium and right ventricle. The primary outcome was defined as a composite cardiovascular event including cardiovascular-related mortality, acute recurrent heart failure hospitalization, urgent repeat revascularization/myocardial infarction or any hospitalization due to cardiovascular events.

RESULTS

The mean age was 58 ± 14.5 years, and 166 (56.8%) participants were male. The study population was divided into three groups based on the HFA-PEFF score: < 2 (n = 81), 2-4 (n = 159), and ≥ 5 (n = 52). HFA-PEFF score ≥ 5, VE/VCO₂ slope, peak systolic strain rate of the left atrium and resting diastolic blood pressure were independently associated with composite cardiovascular events. Furthermore, the addition of VE/VCO₂ and HFA-PEFF to the base model showed incremental prognostic value for predicting composite cardiovascular events (C-statistic 0.898; integrated discrimination improvement 0.129, p = 0.032; net reclassification improvement 1.043, p ≤0.001).

CONCLUSIONS

CPET could be exploited for the HFA-PEFF approach in terms of incremental prognostic value and diagnosis among patients with unexplained dyspnea with preserved EF.

Influence of exertional oscillatory breathing and its temporal behavior in patients with heart failure and reduced ejection fraction

BACKGROUND

Exertional oscillatory breathing (EOV) represents an emerging prognostic marker in heart failure (HF) patients, however little is known about EOV meaning with respect to its disappearance/persistence during cardiopulmonary exercise test (CPET). The present single-center study evaluated EOV clinical and prognostic impact in a large cohort of reduced ejection fraction HF patients (HFrEF) and, contextually, if a specific EOV temporal behavior might be an addictive risk predictor.

METHODS AND RESULTS

Data from 1.866 HFrEF patients on optimized medical therapy were analysed. The primary cardiovascular (CV) study end-point was cardiovascular death, heart transplantation or LV assistance device (LVAD) implantation at 5-years. For completeness a secondary end-point of total mortality at 5- years was also explored. EOV presence was identified in 251 patients (13%): 142 characterized by EOV early cessation (Group A) and 109 by EOV persistence during the whole CPET (Group B). The entire EOV Group showed worse clinical and functional status than NoEOV Group (n = 1.615) and, within the EOV Group, Group B was characterized by a more severe HF. At CV survival analysis, EOV patients showed a poorer outcome than the NoEOV Group (events 27.1% versus 13.1%, p < 0.001) both unpolished and after matching for main confounders. Instead, no significant differences were found between EOV Group A and B with respect to CV outcome. Conversely the analysis for total mortality failed to be significant.

CONCLUSIONS

Our analysis, albeit retrospective, supports the inclusion of EOV into a CPET-centered clinical and prognostic evaluation of the HFrEF patients. EOV characterizes per se a more advanced HFrEF stage with an unfavorable CV outcome. However, the EOV persistence, albeit suggestive of a more severe HF, does not emerge as a further prognostic marker.

Excess ventilation and exertional dyspnoea in heart failure and pulmonary hypertension

Increased ventilation relative to metabolic demands, indicating alveolar hyperventilation and/or increased physiological dead space (excess ventilation), is a key cause of exertional dyspnoea. Excess ventilation has assumed a prominent role in the functional assessment of patients with heart failure (HF) with reduced (HFrEF) or preserved (HFpEF) ejection fraction, pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). We herein provide the key pieces of information to the caring physician to 1) gain unique insights into the seeds of patients' shortness of breath and 2) develop a rationale for therapeutically lessening excess ventilation to mitigate this distressing symptom. Reduced bulk oxygen transfer induced by cardiac output limitation and/or right ventricle-pulmonary arterial uncoupling increase neurochemical afferent stimulation and (largely chemo-) receptor sensitivity, leading to alveolar hyperventilation in HFrEF, PAH and small-vessel, distal CTEPH. As such, interventions geared to improve central haemodynamics and/or reduce chemosensitivity have been particularly effective in lessening their excess ventilation. In contrast, 1) high filling pressures in HFpEF and 2) impaired lung perfusion leading to ventilation/perfusion mismatch in proximal CTEPH conspire to increase physiological dead space. Accordingly, 1) decreasing pulmonary capillary pressures and 2) mechanically unclogging larger pulmonary vessels (pulmonary endarterectomy and balloon pulmonary angioplasty) have been associated with larger decrements in excess ventilation. Exercise training has a strong beneficial effect across diseases. Addressing some major unanswered questions on the link of excess ventilation with exertional dyspnoea under the modulating influence of pharmacological and nonpharmacological interventions might prove instrumental to alleviate the devastating consequences of these prevalent diseases.