347 From arterial hypertension to left ventricular hypertrophy and heart failure: role of cardiopulmonary exercise testing in heart failure with preserved ejection fraction

Aims Arterial hypertension (AHT) represents the leading cause of heart failure (HF). A complex cardiovascular (CV) continuum of events leads to the progression from AHT to left ventricular hypertrophy (LVH), the hallmark of hypertensive heart (HH), towards heart failure with preserved ejection fraction (HFpEF) or reduced ejection fraction (HFrEF). Cardiopulmonary exercise testing (CPET) represents an important tool to evaluate HF patients (both with HFpEF and HFrEF) allowing quantification of functional capacity and mechanisms of dyspnoea as well as providing prognostic markers. To investigate CPET responses in AHT patients at various stages of disease progression from AHT to LVH and HF with preserved and reduced ejection fraction. Methods and results From a CPET registry of 1.397 consecutive subjects, 92 patients were selected (matched according to age, gender, BMI, CV risk factors, beta-blockers) and divided into four groups: 23 AHT patients without LVH, 23 HH patients, 23 HFpEF patients and 23 HFrEF. HFrEF were defined according to LV-EF values while HFpEF were defined according to the presence of NYHA Class ≥2 and HFA-PEFF Score. Mean age was 65 ± 10 years, mean BMI was 28.5 ± 5, male gender was prevalent 83% and 33% had diabetes. Both HFpEF and HFrEF showed lower cardiorespiratory fitness (peak VO2; P < 0.001), cardiovascular efficiency (VO2/Watt slope: P < 0.001), oxygen pulse (VO2/HR: P < 0.001), cardiac output (P < 0.001) and stroke volume (P < 0.001) at peak as well as lower chronotropic response (P < 0.001), ventilatory efficiency (VE/VCO2 slope: P < 0.001), and heart rate recovery (HRR: P = 0.004) compared with both AHT and HH groups. Interestingly, no differences between HFpEF and HFrEF have been found in all CPET data except for chronotropic response (using Tanaka equation), lower in HFpEF (37.5 ± 16.5 vs. 53.5 ± 20.5; P < 0.001) and ventilatory efficiency, lower in HFrEF (VE/VCO2 slope: 32 ± 5 vs. 37 ± 10; P < 0.001). Finally, adding functional capacity (peak VO2) data to ESC Criteria an improvement in HFpEF diagnosis accuracy was found, with 82% sensitivity and 90% specificity (AUC: 859—95% CI: 754–963; P < 0.0001). Conclusions Despite the intrinsic differences in ejection fraction, both HFpEF and HFrEF shares similar cardiopulmonary mechanisms and cardiovascular responses to exercise. CPET may represent a useful tool in order to identify and stratify hypertensive heart patients with HFpEF with high diagnostic accuracy.

Cardiopulmonary exercise testing in interstitial lung diseases and the value of ventilatory efficiency

Interstitial lung diseases (ILDs) are diverse parenchymal pulmonary disorders, primarily characterised by alveolar and interstitial inflammation and/or fibrosis, and sharing pathophysiological similarities. Thus, patients generally harbour common respiratory symptoms, lung function abnormalities and modified exercise adaptation. The most usual and disabling complaint is exertional dyspnoea, frequently responsible for premature exercise interruption. Cardiopulmonary exercise testing (CPET) is increasingly used for the clinical assessment of patients with ILD. This is because exercise performance or dyspnoea on exertion cannot reliably be predicted by resting pulmonary function tests. CPET, therefore, provides an accurate evaluation of functional capacity on an individual basis. CPET can unmask anomalies in the integrated functions of the respiratory, cardiovascular, metabolic, peripheral muscle and neurosensory systems in ILDs. CPET uniquely provides an evaluation of all above aspects and can help clinicians shape ILD patient management. Preliminary evidence suggests that CPET may also generate valuable prognostic information in ILDs and can be used to shed light on the presence of associated pulmonary hypertension. This review aims to provide comprehensive and updated evidence concerning the clinical utility of CPET in ILD patients, with particular focus on the physiological and clinical value of ventilatory efficiency (V˙E/V˙CO2).

Ventilatory efficiency and its clinical and prognostic value in adults with cystic fibrosis

Cystic fibrosis, due to the absence or abnormal function of the cystic fibrosis transmembrane conductance regulator, is the most common life-limiting autosomal recessive genetic disorder among the Caucasian population. The lungs are particularly affected due to thick and tenacious mucus causing parenchymal anomalies ranging from bronchiectasis, progressive airflow limitation, respiratory infections, lung destruction and ultimately respiratory failure. Despite the remarkable advances in treatment that have greatly improved survival, most patients experience progressive exercise curtailment, with the consequence that a growing number of patients with cystic fibrosis will be referred for exercise-based evaluations in the forthcoming years. Cardiopulmonary exercise testing, in particular, is a useful tool to assess the mechanisms of exercise intolerance in individual patients that may have treatment and prognostic implications. In this review, we will focus on ventilatory efficiency and its clinical and prognostic value in adults with cystic fibrosis.

Prognostic value of cardiopulmonary exercise testing in valvular heart disease

Introduction Cardiopulmonary exercise testing (CEPT) is not routinely used for the assessment of valvular heart disease (VHD) patients. The cutoff values of percentage of predicted peak VO2 and ventilatory efficiency parameters that carry out a bad prognosis have been predominantly validated in heart failure. The aim of this study was to analyze the prognostic value of CPET parameters in a broad population of VHD patients. Methods 163 patients (51% female) with moderate or severe VHD who underwent a CEPT (n=197) at their physician's discretion from 2017 until 2019 were included. We calculated the net reclassification index of CPET, compared to the classical clinical or echocardiographic parameters, regarding the need for surgical indication. Also, the predictive value of CPET for death and symptom development during follow-up was estimated using regression analysis. Results At inclusion, all patients were asymptomatic or with minimal equivocal symptoms. Aortic valvular lesions were the most common (47%), followed by mitral valvular disease (44%). There was a predominance of severe valvular heart disease (71%) and most of the CEPTs were performed on a treadmill (74%). The percentage of predicted peak VO2 was 76±18% and at anaerobic threshold was 61±18%. The mean follow-up time was 15±10 months. There were 5 deaths (3%) and 24 patients became symptomatic. The net reclassification index of CPET over either clinical or echocardiographic parameters was 46%. The CEPT parameters that predicted increased risk of death were VE/VCO2 slope (p=0.009), % of predicted peak VO2 (p=0.049) and Eq CO2 at anaerobic threshold (p=0.047). None of the CEPT parameters was predictive of symptom development during follow-up, however, in the subgroup of patients who became clearly symptomatic, the ventilatory efficiency parameters were similar to the cut off values that confer bad prognosis (see Table in Figure). Conclusion In our series, CPET added prognostic mortality value to patients with VHD. The cut off values used for patients with HF can also be applied in a VHD population. In addition, CEPT clearly improved the clinical decision for surgical referral. Nevertheless, these results need to be validated in a broader population. FUNDunding Acknowledgement Type of funding sources: None.

Ventilatory efficiency in athletes, asthma and obesity

During submaximal exercise, minute ventilation (V′E) increases in proportion to metabolic rate (i.e. carbon dioxide production (V′CO2)) to maintain arterial blood gas homeostasis. The ratio V′E/V′CO2, commonly termed ventilatory efficiency, is a useful tool to evaluate exercise responses in healthy individuals and patients with chronic disease. Emerging research has shown abnormal ventilatory responses to exercise (either elevated or blunted V′E/V′CO2) in some chronic respiratory and cardiovascular conditions. This review will briefly provide an overview of the physiology of ventilatory efficiency, before describing the ventilatory responses to exercise in healthy trained endurance athletes, patients with asthma, and patients with obesity. During submaximal exercise, the V′E/V′CO2 response is generally normal in endurance-trained individuals, patients with asthma and patients with obesity. However, in endurance-trained individuals, asthmatics who demonstrate exercise induced-bronchoconstriction, and morbidly obese individuals, the V′E/V′CO2 can be blunted at maximal exercise, likely because of mechanical ventilatory constraint.

Power Output and Efficiency During Supine, Recumbent, and Upright Cycle Ergometry

Recumbent and supine cycling are common exercise modes in rehabilitation and clinical settings but the influence of postures on work efficiency is unclear. Therefore, the aim of this study was to compare metabolic and ventilatory efficiency during upright, recumbent, and supine postures. Potential differences should be assessed for suitable diagnostics and for prescriptions of training that probably is performed in alternative postures. Eighteen healthy subjects (age: 47.2 ± 18.4 years; 10 female, 8 male) participated in the study and each completed three incremental cycle ergometer tests until exhaustion in upright, recumbent (40°), and supine positions. Gas exchange, heart rate (HR), and lactate concentrations were analyzed and efficiency was calculated subsequently. Testing sessions were performed in random order within a 2-week period. Upright cycling resulted in significantly higher peak values [power output, oxygen uptake (Vo2), HR] as well as performance at lactate and ventilatory thresholds in comparison to recumbent or supine positions. Vco2/Vo2 slope and ventilatory efficiency (VE/Vco2 slope) were not affected by posture. Aerobic work efficiency (Vo2/P slope) and gross efficiency (GE) differed significantly between postures. Hereby, GE was lowest in supine cycling, particularly obvious in a mainly aerobic condition at 70 Watt [Median 11.6 (IQR 10.9–13.3) vs. recumbent: 15.9 (IQR 15.6–18.3) and upright: 17.4 (IQR 15.1–18.3)]. Peak power as well as GE and work efficiency values are influenced by cycling position, reinforcing the importance of adjusting test results for training prescriptions. Surprisingly, ventilatory efficiency was not affected in this study and therefore does not seem to falsify test results for pulmonary diagnostics.