Theoretical rationale and practical recommendations for cardiopulmonary exercise testing in patients with chronic heart failure

CO-CREATION-HF protocol: clinical trial to evaluate the impact of a comprehensive and hybrid cardiac rehabilitation model on patients with heart failure

Introduction

Comprehensive, hybrid cardiac rehabilitation (CR) models have been scantly investigated in heart failure (HF) populations, particularly in low-resource settings. CO-CREATION-HF aims to evaluate the effectiveness of such a model compared to supervised exercise alone.

Methods and analysis

A 2 parallel-arm, multi-center randomized clinical superiority trial will be conducted with blinded outcome assessment. 152 HF patients (NYHA class II or III) will be recruited consecutively, and randomly assigned using permuted blocks; allocation will be concealed. The 12-week intervention will include evaluation, medical and nurse management, aerobic interval training, resistance exercise training, psychosocial support, and education. These will initially be delivered in a center, transitioning to home in 4 stages. Controls will receive similar management, but face-to-face continuous aerobic exercise sessions and resistance exercises. The main outcomes are cardiorespiratory fitness (VO2 max), functional capacity (m from 6 MWT), and quality of life (Minnesota Living with Heart Failure Questionnaire). Program adherence and completion, NT-proBNP, functioning, all-cause and HF-specific mortality and hospitalization, muscle strength, adverse events and cost will be secondary outcomes. These will be measured at baseline, end of intervention, and 12-month follow-up. The sample size was calculated considering 90% power, a significance level of 5%, a between-group difference equivalent to 1/2 MET, and a 10% potential loss to follow-up. Intention-to-treat analysis will be considered. Between-group differences will be assessed using Student's t-tests or Z-tests along with 95% confidence intervals, and the rate ratio will be computed to compare mortality.

Ethics and dissemination

The study protocol and the Informed Consent form were approved by Ethical Committees at the Universidad de La Frontera (No. 081-23) and each center participating. Research findings will be disseminated to the scientific community and will be shared with relevant stakeholder groups and policy-makers. Finally, investigators shall reach HF patients via various dissemination channels such as social media.

Clinical Trial Registration

clinicaltrials.gov, identifier (NCT06313684).

Responses to incremental exercise and the impact of the coexistence of HF and COPD on exercise capacity: a follow-up study

Our aim was to evaluate: (1) the prevalence of coexistence of heart failure (HF) and chronic obstructive pulmonary disease (COPD) in the studied patients; (2) the impact of HF + COPD on exercise performance and contrasting exercise responses in patients with only a diagnosis of HF or COPD; and (3) the relationship between clinical characteristics and measures of cardiorespiratory fitness; (4) verify the occurrence of cardiopulmonary events in the follow-up period of up to 24 months years. The current study included 124 patients (HF: 46, COPD: 53 and HF + COPD: 25) that performed advanced pulmonary function tests, echocardiography, analysis of body composition by bioimpedance and symptom-limited incremental cardiopulmonary exercise testing (CPET) on a cycle ergometer. Key CPET variables were calculated for all patients as previously described. The [Formula: see text]E/[Formula: see text]CO2 slope was obtained through linear regression analysis. Additionally, the linear relationship between oxygen uptake and the log transformation of [Formula: see text]E (OUES) was calculated using the following equation: [Formula: see text]O2 = a log [Formula: see text]E + b, with the constant 'a' referring to the rate of increase of [Formula: see text]O2. Circulatory power (CP) was obtained through the product of peak [Formula: see text]O2 and peak systolic blood pressure and Ventilatory Power (VP) was calculated by dividing peak systolic blood pressure by the [Formula: see text]E/[Formula: see text]CO2 slope. After the CPET, all patients were contacted by telephone every 6 months (6, 12, 18, 24) and questioned about exacerbations, hospitalizations for cardiopulmonary causes and death. We found a 20% prevalence of HF + COPD overlap in the studied patients. The COPD and HF + COPD groups were older (HF: 60 ± 8, COPD: 65 ± 7, HF + COPD: 68 ± 7). In relation to cardiac function, as expected, patients with COPD presented preserved ejection fraction (HF: 40 ± 7, COPD: 70 ± 8, HF + COPD: 38 ± 8) while in the HF and HF + COPD demonstrated similar levels of systolic dysfunction. The COPD and HF + COPD patients showed evidence of an obstructive ventilatory disorder confirmed by the value of %FEV1 (HF: 84 ± 20, COPD: 54 ± 21, HF + COPD: 65 ± 25). Patients with HF + COPD demonstrated a lower work rate (WR), peak oxygen uptake ([Formula: see text]O2), rate pressure product (RPP), CP and VP compared to those only diagnosed with HF and COPD. In addition, significant correlations were observed between lean mass and peak [Formula: see text]O2 (r: 0.56 p < 0.001), OUES (r: 0.42 p < 0.001), and O2 pulse (r: 0.58 p < 0.001), lung diffusing factor for carbon monoxide (DLCO) and WR (r: 0.51 p < 0.001), DLCO and VP (r: 0.40 p: 0.002), forced expiratory volume in first second (FEV1) and peak [Formula: see text]O2 (r: 0.52; p < 0.001), and FEV1 and WR (r: 0.62; p < 0.001). There were no significant differences in the occurrence of events and deaths contrasting both groups. The coexistence of HF + COPD induces greater impairment on exercise performance when compared to patients without overlapping diseases, however the overlap of the two diseases did not increase the probability of the occurrence of cardiopulmonary events and deaths when compared to groups with isolated diseases in the period studied. CPET provides important information to guide effective strategies for these patients with the goal of improving exercise performance and functional capacity. Moreover, given our findings related to pulmonary function, body composition and exercise responses, evidenced that the lean mass, FEV1 and DLCO influence important responses to exercise.

Eccentric Left Ventricular Hypertrophy and Left and Right Cardiac Function in Chronic Heart Failure with or without Coexisting COPD: Impact on Exercise Performance

AIM

Our aim was to assess: 1) the impact of the eccentric left ventricular hypertrophy (ELVH) on exercise performance in patients diagnosed with chronic heart failure (CHF) alone and in patients with co-existing CHF and chronic obstructive pulmonary disease (COPD) and 2) the relationship between left and right cardiac function measurements obtained by doppler echocardiography, clinical characteristics and primary measures of cardiorespiratory fitness.

METHODS

The current study included 46 patients (CHF:23 and CHF+COPD:23) that performed advanced pulmonary function tests, echocardiography and symptom-limited, incremental cardiopulmonary exercise testing (CPET) on a cycle ergometer.

RESULTS

Patients with CHF+COPD demonstrated a lower work rate, peak oxygen uptake (VO2), oxygen pulse, rate pressure product (RPP), circulatory power (CP) and ventilatory power (VP) compared to those only diagnosed with CHF. In addition, significant correlations were observed between VP and relative wall thickness (r: 0.45 p: 0.03),VE/VCO2 intercept and Mitral E/e' ratio (r: 0.70 p: 0.003) in the CHF group. Significant correlations were found between indexed left ventricle mass and RPP (r: -0.47; p: 0.02) and relative VO2 and right ventricle diameter (r: -0.62; p: 0.001) in the CHF+COPD group.

CONCLUSION

Compared to a diagnosis of CHF alone, a combined diagnosis of CHF+COPD induced further impairments in cardiorespiratory fitness. Moreover, echocardiographic measures of cardiac function are related to cardiopulmonary exercise performance and therefore appear to be an important therapeutic target when attempting to improve exercise performance and functional capacity.

Peak Oxygen Uptake and Exercise Capacity of Children Undergoing Leukemia Treatment

The aim of the study was to assess the exercise capacity (VO_2peak) of children undergoing leukemia treatment and to compare the results with healthy children. Furthermore, we assessed the influence of treatment methods on the level of exercise capacity and the increase in sedentary behaviors. The study comprised 21 children (12 boys and 9 girls) undergoing treatment for acute lymphoblastic leukemia (ALL) (n = 13) and acute myeloid leukemia (AML) (n = 8). The subjects were aged 7-13 years (mean age 10.7, SD 2.0 years). Cardiorespiratory fitness was assessed by using the ergospirometry test. Progressive Godfrey protocol was performed. The level of physical activity was assessed by using the questions from the Health Behavior in School-Aged Children (HBSC 2018) questionnaire. The study results showed that children undergoing leukemia treatment were characterized by a reduced level of exercise capacity. The measured value of VO_2peak in the group of treated children was, on average, 22.16 mL·kg^-1·min^-1. The mean values of VO_2peak predicted for this age group were 45.48 mL·kg^-1·min^-1 (SD, 3.8). The measured value of VO_2peak in the study group with the division into age groups was, on average, 21.21 mL·kg^-1·min^-1 in the group of children aged 7-10 years. In the group of children aged 11-13 years, this parameter was 22.64 mL·kg^-1·min^-1. Lack of physical activity and failure to meet the standards for the minimum level of weekly physical activity (MVPA index-moderate-to-vigorous physical activity) probably contribute to the deterioration in exercise capacity level of cancer-treated children.

Physical Activity Is Higher in Patients with Left Ventricular Assist Device Compared with Chronic Heart Failure

PURPOSE

Left ventricular assist devices (LVAD) are associated with an increased aerobic capacity in patients with chronic heart failure (CHF). However, studies evaluating the impact of LVAD implantation on physical activity (PA) are lacking. The aim of this study was to compare daily PA levels in participants with LVAD with well-matched CHF participants.

METHODS

Sixteen participants with an LVAD (age, 59.1 ± 10.8 yr) were case-matched to 16 participants with advanced CHF (age, 58.3 ± 8.7 yr), who were listed or being considered for cardiac transplantation. Participants underwent a cardiopulmonary exercise test to determine peak oxygen consumption (V˙O2 peak). Physical activity was monitored continuously for seven consecutive days with an Actiheart monitor.

RESULTS

V˙O2 peak in the CHF group (12.3 ± 3.5 mL·kg·min) was not significantly different to the LVAD group before LVAD implantation (10.4 ± 2.1 mL·kg·min), but was lower than in the LVAD group after implantation (15.8 ± 4.3 mL·kg·min; P < 0.05). Physical activity was higher in the LVAD (19.7 ± 6.4 kJ·kg·d) compared with the CHF group (11.6 ± 6.9 kJ·kg·d; P = 0.001). The LVAD participants spent more time performing moderate-intensity PA than their CHF counterparts (median, 26 min·d; interquartile range, 24-40 min·d vs median, 12 min·d; interquartile range, 9-16 min·d; P < 0.001). Physical activity was correlated with V˙O2 peak (r = 0.582; P = 0.001) across participants in the CHF and LVAD groups.

CONCLUSIONS

Higher levels of PA were observed in participants with LVAD compared with patients with advanced CHF. This may be due to a higher V˙O2 peak, resulting in an improved capacity to perform activities of daily living with less symptoms.

Cerebral blood flow responses to exercise are enhanced in left ventricular assist device patients after an exercise rehabilitation program

Cerebral blood flow during exercise is impaired in patients with heart failure implanted with left ventricular assist devices (LVADs). Our aim was to determine whether a 3-mo exercise training program could mitigate cerebrovascular dysfunction. Internal carotid artery (ICA) blood flow and intracranial middle (MCAv) and posterior cerebral (PCAv) artery velocities were measured continuously using Doppler ultrasound, alongside cardiorespiratory measures at rest and in response to an incremental cycle ergometer exercise protocol in 12 LVAD participants (5 female, 53.6 ± 11.8 yr; 84.2 ± 15.7 kg; 1.73 ± 0.08) pre- (PreTR) and post- (PostTR) completion of a 3-mo supervised exercise rehabilitation program. At rest, only PCAv was different PostTR (38.1 ± 10.4 cm/s) compared with PreTR (43.0 ± 10.8 cm/s; P < 0.05). PreTR, the reduction in PCAv observed from rest to exercise (5.2 ± 1.8%) was mitigated PostTR (P < 0.001). Similarly, exercise training enhanced ICA flow during submaximal exercise (~8.6 ± 13.7%), resulting in increased ICA flow PostTR compared with a reduced flow PreTR (P < 0.001). Although both end-tidal partial pressure of carbon dioxide and mean arterial pressure responses during incremental exercise were greater PostTR than PreTR, only the improved PETCO2 was related to the improved ICA flow (R² = 0.14; P < 0.05). Our findings suggest that short-term exercise training improves cerebrovascular function during exercise in patients with LVADs. This finding should encourage future studies investigating long-term exercise training and cerebral and peripheral vascular adaptation.NEW & NOTEWORTHY Left ventricular assist devices, now used as destination therapy in end-stage heart failure, enable patients to undertake rehabilitative exercise training. We show, for the first time in humans, that training improves cerebrovascular function during exercise in patients with left ventricular assist devices. This finding may have implications for cerebrovascular health in patients with heart failure.

Treadmill Running in Established Phase Arthritis Inhibits Joint Destruction in Rat Rheumatoid Arthritis Models

Exercise therapy inhibits joint destruction by suppressing pro-inflammatory cytokines. The efficacy of pharmacotherapy for rheumatoid arthritis differs depending on the phase of the disease, but that of exercise therapy for each phase is unknown. We assessed the differences in the efficacy of treadmill running on rheumatoid arthritis at various phases, using rat rheumatoid arthritis models. Rats with collagen-induced arthritis were used as rheumatoid arthritis models, and the phase after immunization was divided as pre-arthritis and established phases. Histologically, the groups with forced treadmill running in the established phase had significantly inhibited joint destruction compared with the other groups. The group with forced treadmill running in only the established phase had significantly better bone morphometry and reduced expression of connexin 43 and tumor necrosis factor α in the synovial membranes compared with the no treadmill group. Furthermore, few cells were positive for cathepsin K immunostaining in the groups with forced treadmill running in the established phase. Our results suggest that the efficacy of exercise therapy may differ depending on rheumatoid arthritis disease activity. Active exercise during phases of decreased disease activity may effectively inhibit arthritis and joint destruction.

Treadmill Running Ameliorates Destruction of Articular Cartilage and Subchondral Bone, Not Only Synovitis, in a Rheumatoid Arthritis Rat Model

We analyzed the influence of treadmill running on rheumatoid arthritis (RA) joints using a collagen-induced arthritis (CIA) rat model. Eight-week-old male Dark Agouti rats were randomly divided into four groups: The control group, treadmill group (30 min/day for 4 weeks from 10-weeks-old), CIA group (induced CIA at 8-weeks-old), and CIA + treadmill group. Destruction of the ankle joint was evaluated by histological analyses. Morphological changes of subchondral bone were analyzed by μ-CT. CIA treatment-induced synovial membrane invasion, articular cartilage destruction, and bone erosion. Treadmill running improved these changes. The synovial membrane in CIA rats produced a large amount of tumor necrosis factor-α and Connexin 43; production was significantly suppressed by treadmill running. On μ-CT of the talus, bone volume fraction (BV/TV) was significantly decreased in the CIA group. Marrow star volume (MSV), an index of bone loss, was significantly increased. These changes were significantly improved by treadmill running. Bone destruction in the talus was significantly increased with CIA and was suppressed by treadmill running. On tartrate-resistant acid phosphate and alkaline phosphatase (TRAP/ALP) staining, the number of osteoclasts around the pannus was decreased by treadmill running. These findings indicate that treadmill running in CIA rats inhibited synovial hyperplasia and joint destruction.

Can proportional ventilation modes facilitate exercise in critically ill patients? A physiological cross-over study : Pressure support versus proportional ventilation during lower limb exercise in ventilated critically ill patients

Background

Early exercise of critically ill patients may have beneficial effects on muscle strength, mass and systemic inflammation. During pressure support ventilation (PSV), a mismatch between demand and assist could increase work of breathing and limit exercise. A better exercise tolerance is possible with a proportional mode of ventilation (Proportional Assist Ventilation, PAV+ and Neurally Adjusted Ventilatory Assist, NAVA). We examined whether, in critically ill patients, PSV and proportional ventilation have different effects on respiratory muscles unloading and work efficiency during exercise.

Methods

Prospective pilot randomized cross-over study performed in a medico-surgical ICU. Patients requiring mechanical ventilation >48 h were enrolled. At initiation, the patients underwent an incremental workload test on a cycloergometer to determine the maximum level capacity. The next day, 2 15-min exercise, at 60% of the maximum capacity, were performed while patients were randomly ventilated with PSV and PAV+ or NAVA. The change in oxygen consumption (ΔVO₂, indirect calorimetry) and the work efficiency (ratio of ΔVO₂ per mean power) were computed.

Results

Ten patients were examined, 6 ventilated with PSV/PAV+ and 4 with PSV/NAVA. Despite the same mean inspiratory pressure at baseline between the modes, baseline VO₂ (median, IQR) was higher during proportional ventilation (301 ml/min, 270–342) compared to PSV (249 ml/min, 206–353). Exercise with PSV was associated with a significant increase in VO₂ (ΔVO₂, median, IQR) (77.6 ml/min, 59.9–96.5), while VO₂ did not significantly change during exercise with proportional modes (46.3 ml/min, 5.7–63.7, p < 0.05). As a result, exercise with proportional modes was associated with a better work efficiency than with PSV. The ventilator modes did not affect patient’s dyspnea, limb fatigue, distance, hemodynamics and breathing pattern.

Conclusions

Proportional ventilation during exercise results in higher work efficiency and less increase in VO₂ compared to ventilation with PSV. These preliminary findings suggest that proportional ventilation could enhance the training effect and facilitate rehabilitation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-017-0289-y) contains supplementary material, which is available to authorized users.

Metabolic profiles in heart failure due to non-ischemic cardiomyopathy at rest and under exercise

AIMS

Identification of metabolic signatures in heart failure (HF) patients and evaluation of their diagnostic potential to discriminate HF patients from healthy controls during baseline and exercise conditions.

METHODS

Plasma samples were collected from 22 male HF patients with non-ischemic idiopathic cardiomyopathy and left ventricular systolic dysfunction and 19 healthy controls before (t0), at peak (t1) and 1 h after (t2) symptom-limited cardiopulmonary exercise testing. Two hundred fifty-two metabolites were quantified by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography (LC)-MS/MS-based metabolite profiling.

RESULTS

Plasma metabolite profiles clearly differed between HF patients and controls at t0 (P < 0.05). The metabolic signature of HF was characterized by decreased levels of complex lipids and fatty acids, notably phosphatidylcholines, cholesterol, and sphingolipids. Moreover, reduced glutamine and increased glutamate plasma levels, significantly increased purine degradation products, as well as signs of impaired glucose metabolism were observed. The metabolic differences increased strongly according to New York Heart Association functional class and the addition of three metabolites further improved prediction of exercise capacity (Q² = 0.24 to 0.35). Despite a high number of metabolites changing significantly with exercise (30.2% at t1/t0), the number of significant alterations between HF and controls was almost unchanged at t₁ and t₂ (30.7 and 29.0% vs. 31.3% at t₀) with a similar predictive group separation (Q² = 0.50 for t0, 0.52 for t1, and 0.56 for t2, respectively).

CONCLUSIONS

Our study identified a metabolic signature of non-ischemic HF with prominent changes in complex lipids including phosphatidylcholines, cholesterol, and sphingolipids. The metabolic changes were already evident at rest and largely preserved under exercise.

Aerobic exercise effect on prognostic markers for systolic heart failure patients: a systematic review and meta-analysis

From previous systematic reviews and meta-analyses, there is consensus about the positive effect of exercise training on exercise capacity for systolic heart failure (HF); however, the effect on actual prognostic markers such as NTproBNP and minute ventilation/carbon dioxide production (VE/VCO2) slope has not been evaluated. The primary aim of the proposed study is to determine the effect of aerobic exercise training (AEX) on the VE/VCO2 slope and NTproBNP. The following databases (up to February 30, 2013) were searched with no language limitations: CENTRAL (The Cochrane Library 2013, issue 2), MEDLINE (from January 1966), EMBASE (from January 1980), and Physiotherapy Evidence Database (PEDro) (from January 1929). We screened reference lists of articles and also conducted an extensive hand search of the literature. Randomized controlled trials of exercise-based interventions with 2-month follow-up or longer compared to usual medical care or placebo were included. The study population comprised adults aged between 18 and 65 years, with evidence of chronic systolic heart failure (LVEF < 45 % and baseline NTproBNP > 300 pg/ml). Two review authors independently extracted data on study design, participants, interventions, and outcomes. We assessed the risk of bias using PEDro scale. We calculated mean differences (MD) or standardized mean differences between intervention and control groups for outcomes with sufficient data; for other outcomes, we described findings from individual studies. Eight studies involving a total of 408 participants met the inclusion criteria across the NTproBNP (5 studies with 191 patients) and VE/VCO2 slope (4 studies with 217 patients). Aerobic exercise significantly improved NTproBNP by a MD of -817.75 [95 % confidence interval (CI) -929.31 to -706.19]. Mean differences across VE/VCO2 slope were -6.55 (95 % CI -7.24 to -5.87). Those patients' characteristics and exercise were similar (frequency = 3-5 times/week; duration = 20-50 min/day; intensity = 60-80 % of VO2 peak) on the included studies. Moreover, the risk of bias across all studies was homogeneous (PEDro scale = 7-8 points). However, based on the statistical analysis, the heterogeneity among the studies was still high, which is related to the variable characteristics of the studies. Aerobic exercise may be effective at improving NTproBNP and the VE/VCO2 slope in systolic HF patients, but these effects are limited to a specific HF population meeting specific inclusion criterion in a limited number of studies. Future randomized controlled studies including diastolic and HF overleap with pulmonary diseases are needed to better understand the exact influence of AEX.

Parasympathetic reinnervation accompanied by improved post-exercise heart rate recovery and quality of life in heart transplant recipients

Although sympathetic reinnervation is accompanied by the improvement of exercise tolerability during the first years after heart transplantation (HTx), little is known about parasympathetic reinnervation and its clinical impact. We enrolled 21 recipients (40 ± 16 years, 71% male) who had received successive cardiopulmonary exercise testing at 6 months, and 1 and 2 years after HTx. Exercise parameters such as peak oxygen consumption or achieved maximum load remained unchanged, whereas recovery parameters including heart rate (HR) recovery during 2 minutes and the delay of peak HR, which are influenced by parasympathetic activity, improved significantly during post-HTx 2 years (P < 0.05 for both). HR variability was analysed at post-HTx 6 months in 18 recipients, and high frequency power, representing parasympathetic activity, was significantly associated with the 2 recovery parameters (P < 0.05 for all). We also assessed quality of life using the Minnesota Living with Heart Failure (HF) Questionnaire at post-HTx 6 months and 2 years in the same 18 recipients, and those with improved recovery parameters enjoyed a better HF-specific quality of life (P < 0.05 for both). In conclusion, parasympathetic reinnervation emerges along with improved post-exercise recovery ability of HR and quality of life during post-HTx 2 years.

Validation of a cardiopulmonary exercise test score in heart failure

BACKGROUND

Cardiopulmonary exercise test (CPX) responses are strong predictors of outcomes in patients with heart failure. We recently developed a CPX score that integrated the additive prognostic information from CPX. The purpose of this study was to validate the score in a larger, independent sample of patients.

METHODS AND RESULTS

A total of 2625 patients with heart failure underwent CPX and were followed for cardiovascular (CV) mortality and major CV events (death, transplantation, left ventricular assist device implantation). Net reclassification improvement (NRI) for the score and each of its components were determined at 3 years. The VE/VCO2 slope was the strongest predictor of risk and was attributed a relative weight of 7, with weighted scores for abnormal heart rate recovery, oxygen uptake efficiency slope, end-tidal CO2 pressure, and peak VO2 having scores of 5, 3, 3, and 2, respectively. A summed score of >15 was associated with an annual mortality rate of 12.2% and a relative risk >9 for total events, whereas a score of <5 was associated with an annual mortality rate of 1.2%. The composite score was the most accurate predictor of CV events among all CPX responses considered (C indexes, 0.70 for CV mortality and 0.72 for the composite outcome). Each component of the score provided significant NRI compared with peak VO2 (category-free NRI, 0.61-0.77), and the score provided significant NRI above clinical risk factors for both CV events and mortality (NRI, 0.63 and 0.65 for CPX score compared with clinical variables alone).

CONCLUSIONS

These results validate the application of a simple, integrated multivariable score based on readily available CPX responses.

Cardiopulmonary exercise test predicts sustained ventricular arrhythmias in chronic heart failure

BACKGROUND

The cardiopulmonary exercise test (CPX) is an affordable tool for risk prediction in patients with chronic heart failure (CHF). We aimed to determine the role of CPX parameters in predicting the risk of incidence of sustained ventricular arrhythmias (SVA) in CHF.

METHODS

Sixty-one consecutive patients with CHF enrolled in the Daunia Heart Failure Registry underwent CPX and were followed for 327 ± 247 days. Clinical follow-up was performed every month and anticipated in case of re-hospitalisation for cardiac disease. Incidence of SVA was evaluated by direct clinical examination (ECG, ambulatory ECG).

RESULTS

Patients with episodes of SVA (N 14) showed lower values of pVO2 and PetCO2, and higher values of VE/VCO2, VE/VCO2 slope, and VE%. After correction for age, gender, diabetes, ischaemic heart disease and left ventricular ejection fraction, peak VO2 (hazard ratio (HR) 0.68, 95 % confidence interval (CI) 0.51-0.91, p < 0.05), VE% (HR 1.38, 95 % CI 1.04-1.84, p < 0.05), VE/VCO2 (HR 1.38, 95 % CI 1.04-1.82, p < 0.05), VE/VCO2 slope (HR 1.77, 95 % CI 1.31-2.39, p < 0.01), PetCO2 (HR 0.66, 95 % CI 0.50-0.88, p < 0.01) were found as predictors of SVA. At Kaplan-Meier analysis, lower event-free rates were found in subjects with peak VO2 values below median (log rank p < 0.05), values of VE/VCO2 above mean (p < 0.05), higher VE/VCO2 slope tertiles (p <0.05), and values of PetCO2 below median (p < 0.05).

CONCLUSIONS

CPX provides prognostic independent information for risk of SVA in subjects with CHF.

Teste de esforço cardiopulmonar com protocolo de rampa em adultos com insuficiência cardíaca

INTRODUÇÃO E OBJETIVO: O teste de esforço com protocolo de rampa é descrito como o que mais se adéqua à condição física de indivíduos com insuficiência cardíaca (IC). Porém, não há padronização descrita sobre incrementos de velocidade e inclinação. Este estudo teve como objetivo descrever resultados encontrados a partir da aplicação de um teste de esforço com protocolo de rampa adaptado para indivíduos com IC, classes II e III da New York Heart Association (NYHA). MÉTODOS: 41 indivíduos com média de idade de 46,37 ± 8,98 anos e fração de ejeção de 31,51 ± 9,45% fizeram o teste de esforço com análise de gases expirados em esteira, com protocolo de rampa desenvolvido a partir de critérios definidos pelo estudo de Barbosa e Silva e Sobral. Análise estatística: Foi realizada análise descritiva com distribuição de frequência e o tempo de teste foi apresentado como média ± desvio padrão. Foi realizado o modelo de regressão linear incluindo classe da NYHA, idade e fração de ejeção como variáveis explicativas para tempo de teste. Foi considerado significativo p < 0,05. RESULTADOS: O tempo médio do teste foi 8,89 ± 3,57 minutos e o R alcançado foi 1,12 ± 0,11. Sessenta e um porcento da amostra apresentou duração do teste entre seis e 12 minutos, considerando intervalo de média ± 1 desvio padrão, e 73,2% da amostra apresentou duração entre seis e 15 minutos. CONCLUSÃO: Os achados deste estudo demonstraram que a maioria dos indivíduos com IC finalizou o teste com o protocolo de rampa adaptado dentro da duração considerada adequada pela literatura.

Cardiovascular abnormalities in Klinefelter syndrome

BACKGROUND

Several epidemiological studies have demonstrated an increased mortality from cardiovascular causes in patients with Klinefelter Syndrome (KS). Little information is available about the nature of the underlying cardiovascular abnormalities. Aim of the study was to investigate exercise performance, left ventricular architecture and function, vascular reactivity, and carotid intima-media thickness in a group of patients with KS.

MATERIALS AND METHODS

Sixty-nine patients with KS and 48 age-matched controls participated in our population-controlled study. Forty-eight Klinefelter subjects were on testosterone treatment at the time of the investigation while 21 were naive and underwent a complete Doppler echocardiographic examination, a cardiopulmonary exercise test as well as a vascular study including measures of carotid intima-media thickness and endothelial function with flow-mediated dilation of the brachial artery. Patients with KS on testosterone therapy (n=48) were also matched against a population of men with treated secondary hypogonadism (n=21).

RESULTS

Patients with KS exhibited a wide array of cardiovascular abnormalities including left ventricular diastolic dysfunction, reduced maximal oxygen consumption (p<0.01), increased intima-media thickness (p<0.05) (-34% and +42% vs. controls, respectively) and a high prevalence of chronotropic incompetence (55% of patients, p<0.01). No significant difference was found between treated and untreated KS in variance with men treated for secondary hypogonadism.

CONCLUSION

Left ventricular diastolic dysfunction, impaired cardiopulmonary performance, chronotropic incompetence, and increased intima-media thickness suggest that cardiovascular abnormalities are a common finding in KS that is not reversed by testosterone replacement therapy and may represent the pathophysiological underpinnings of the increased risk of dying from heart disease.

Patients with heart failure in the "intermediate range" of peak oxygen uptake: additive value of heart rate recovery and the minute ventilation/carbon dioxide output slope in predicting mortality

PURPOSE

While patients with heart failure who achieve a peak oxygen uptake (peak VO2) of 10 mL·kg(-1)·min(-1) or less are often considered for intensive surveillance or intervention, those achieving 14 mL·kg(-1)·min(-1) or more are generally considered to be at lower risk. Among patients in the "intermediate" range of 10.1 to 13.9 mL·kg(-1)·min(-1), optimally stratifying risk remains a challenge.

METHODS

Patients with heart failure (N = 1167) referred for cardiopulmonary exercise testing were observed for 21 ± 13 months. Patients were classified into 3 groups of peak VO2 (≤10, 10.1-13.9, and ≥14 mL·kg(-1)·min(-1)). The ability of heart rate recovery at 1 minute (HRR1) and the minute ventilation/carbon dioxide output (VE/VCO2) slope to complement peak VO2 in predicting cardiovascular mortality were determined.

RESULTS

Peak VO2, HRR1 (<16 beats per minute), and the VE/VCO2 slope (>34) were independent predictors of mortality (hazard ratio 1.6, 95% CI: 1.2-2.29, P = .006; hazard ratio 1.7, 95% CI: 1.1-2.5, P = .008; and hazard ratio 2.4, 95% CI: 1.6-3.4, P < .001, respectively). Compared with those achieving a peak VO2 ≥ 14 mL·kg(-1)·min(-1), patients within the intermediate range with either an abnormal VE/VCO2 slope or HRR1 had a nearly 2-fold higher risk of cardiac mortality. Those with both an abnormal HRR1 and VE/VCO2 slope had a higher mortality risk than those with a peak VO2 ≤ 10 mL·kg(-1)·min(-1). Survival was not different between those with a peak VO2 ≤ 10 mL·kg(-1)·min(-1) and those in the intermediate range with either an abnormal HRR1 or VE/VCO2 slope.

CONCLUSIONS

HRR1 and the VE/VCO2 slope effectively stratify patients with peak VO2 within the intermediate range into distinct groups at high and low risk.

Ventilatory power: a novel index that enhances prognostic assessment of patients with heart failure

BACKGROUND

Minute ventilation/CO(2) production (VE/Vco(2)) slope is an index determined by cardiopulmonary exercise testing, which incorporates pertinent cardiac, pulmonary, and skeletal muscle physiology into a substantive composite assessment. The VE/Vco(2) slope has many applications, including utility as a well-validated prognostic gauge for patients with heart failure (HF). In this study, we combine VE/Vco(2) slope with systolic blood pressure, creating a novel index that we labeled ventilatory power. Ventilatory power links the combined physiology inherent in the VE/Vco(2) slope to peripheral pressure, adding an additional dimension pertinent to HF assessment. Whereas the related concept of circulatory power links peak oxygen consumption with peak systolic blood pressure as a prognostic index, we hypothesized that ventilatory power would provide greater prognostic discrimination than VE/Vco2 slope, peak oxygen consumption, and circulatory power for patients with systolic HF.

METHODS AND RESULTS

Patients with systolic HF (left ventricular ejection fraction ≤35%) underwent symptom-limited cardiopulmonary exercise testing as part of routine management and were followed for up to 4 years for major cardiac events (mortality, left ventricular assist device implantation, and heart transplantation). Eight hundred seventy-five patients with HF (left ventricular ejection fraction, 26±9%; mean age, 55±14) were studied. Cardiopulmonary exercise testing indices peak oxygen consumption, VE/Vco(2) slope, circulatory power, and ventilatory power were all predictive of cardiac events (P<0.001). Multivariate analysis demonstrated that ventilatory power was the strongest indicator of prognosis.

CONCLUSIONS

Although circulatory power and traditional cardiopulmonary exercise testing parameters can be used to predict prognosis among patients with HF, ventilatory power provides relatively greater prognostic discrimination and may constitute a relatively more useful composite tool.

Association of cerebral blood flow with the development of cardiac death or urgent heart transplantation in patients with systolic heart failure

AIMS

Although cerebral blood flow (CBF) is known to be low in patients with advanced systolic heart failure (HF), little is known of the prognostic significance of this observation. We investigated whether CBF might be associated with the development of adverse outcomes in systolic HF, and whether it might provide prognostic information in addition to that provided by exercise tests.

METHODS AND RESULTS

We performed a prospective observational study involving 224 systolic HF patients (left ventricular ejection fraction ≤35%). The study endpoint was the occurrence of cardiac death or urgent heart transplantation. Global CBF was measured using radionuclide angiography. Clinical, biochemical, echocardiographic, and exercise data were also obtained. During follow-up (median 36 months), 52 patients experienced death or urgent transplantation. Multivariable analysis showed that global CBF, the minute ventilation/carbon dioxide production (VE/VCO(2)) slope, New York Heart Association functional class ≥III, symptom duration ≥12 months, serum sodium, and serum creatinine were associated with the development of the endpoint. Patients with a CBF <35.4 mL/min/100 g were at increased risk of death or urgent transplantation (hazard ratio = 2.47; 95% confidence interval, 1.35-4.52). The addition of global CBF to a prognostic model including the VE/VCO(2) slope increased the C-index for the prediction of adverse outcomes with borderline significance.

CONCLUSION

Cerebral blood flow was associated with the development of long-term outcomes in systolic HF, and therefore may be useful in identifying patients suitable for heart transplantation. This finding is especially relevant for patients in whom exercise tests may not be performed sufficiently.

Ordering a cardiopulmonary exercise test for your patient: key considerations for the physician

Cardiopulmonary exercise testing (CPX) is a specialized exercise assessment that provides valuable information in a number of patient populations. Physicians are often familiar with standard exercise testing procedures (i.e., the cardiac stress test) and, therefore, appropriately refer patients with signs/symptoms suggestive of myocardial ischemia. However, the procedures surrounding referral for CPX, and the relevance of the data obtained, may not be as widely understood in the medical community. The purpose of the current special report is to provide physicians referring patients for CPX with information on the appropriateness of CPX referral and testing logistics, the identification of an appropriate CPX laboratory for referral, and definitions on key CPX variables that should be included in the final report.

The lowest VE/VCO2 ratio during exercise as a predictor of outcomes in patients with heart failure

BACKGROUND

The lowest minute ventilation (VE) and carbon dioxide production (VCO(2)) ratio during exercise has been suggested to be the most stable and reproducible marker of ventilatory efficiency in patients with heart failure (HF). However, the prognostic power of this index is unknown.

METHODS AND RESULTS

A total of 847 HF patients underwent cardiopulmonary exercise testing (CPX) and were followed for 3 years. The associations between the lowest VE/VCO(2) ratio, maximal oxygen uptake (peak VO(2)), the VE/VCO(2) slope, and major events (death or transplantation) were evaluated using proportional hazards analysis; adequacy of the predictive models was assessed using Akaike information criterion (AIC) weights. There were 147 major adverse events. In multivariate analysis, the lowest VE/VCO(2) ratio (higher ratio associated with greater risk) was similar to the VE/VCO(2) slope in predicting risk (hazard ratios [HR] per unit increment 2.0, 95% CI 1.1-3.4, and 2.2, 95% CI 1.3-3.7, respectively; P < .01), followed by peak VO(2) (HR 1.6, 95% CI 1.1-2.4, P=.01). Patients exhibiting abnormalities for all 3 responses had an 11.6-fold higher risk. The AIC weight for the 3 variables combined (0.94) was higher than any single response or any combination of 2. The model including all 3 responses remained the most powerful after adjustment for beta-blocker use, type of HF, and after applying different cut points for high risk.

CONCLUSIONS

The lowest VE/VCO(2) ratio adds to the prognostic power of conventional CPX responses in HF.

End-tidal CO2 pressure and cardiac performance during exercise in heart failure

INTRODUCTION

In patients with heart failure (HF), end-tidal CO2 pressure (PetCO2) is related to ventricular function at rest and has been shown to predict prognosis. However, little is known about the association between ventricular performance and PetCO2 responses to exercise.

METHODS

Forty-eight patients with HF and 13 normal subjects underwent cardiopulmonary exercise testing (CPX), while cardiac output and other hemodynamic measurements at rest and during exercise were obtained using a novel, noninvasive, bioreactance device based on assessment of relative phase shifts of electric currents injected across the thorax, heart rate, and ventricular ejection time. CPX responses and indices of cardiac performance were compared between normal subjects and HF patients achieving above and below a PetCO2 of 36 mm Hg at the ventilatory threshold (PetCO2@VT).

RESULTS

HF patients with an abnormal PetCO2@VT (<36 mm Hg) had a lower exercise capacity, a lower .VO2@VT, a higher .V_E/.VCO2 slope, and lower oxygen uptake efficiency slope (OUES) values compared with normal subjects and patients achieving a normal PetCO2@VT. Patients with reduced PetCO2@VT had lower peak cardiac output responses to exercise (20.0 +/- 10, 17.8 +/- 6, and 13.7 +/- 7 L x min for normal subjects and HF patients with normal and abnormal PetCO2 responses to exercise, respectively, P = 0.04). PetCO2@VT was inversely related to the .V_E/.VCO2 slope (r = -0.78, P < 0.001) and directly related to the OUES (r = 0.55, P < 0.001).

CONCLUSION

Reduced PetCO2 reflects impairments in the functional, ventilatory, and cardiac performance response to exercise in patients with HF. PetCO2 can supplement other clinical and CPX indices in the functional and prognostic evaluation of patients with HF.

Long-term cardiovascular effects of levothyroxine therapy in young adults with congenital hypothyroidism

CONTEXT

Congenital hypothyroidism (CH) is the most prevalent endocrine disorder in the newborn and is routinely treated with life-long levothyroxine replacement therapy. Although several studies have demonstrated that such therapy may impact on the cardiovascular system, little is known with regard to the effects of long-term levothyroxine administration in patients with CH.

OBJECTIVE

The aim of the current study was to evaluate whether long-term levothyroxine replacement therapy in young adults with CH is associated with cardiovascular abnormalities.

PATIENTS AND METHODS

Thirty young adults with CH aged 18.1 +/- 0.2 yr and 30 age- and sex-matched controls underwent cardiac and carotid Doppler ultrasound and symptom-limited cardiopulmonary exercise testing. Hypothyroidism was diagnosed by neonatal screening, and levothyroxine treatment was initiated within the first month of life and carefully adjusted to maintain TSH levels in the normal range and free T(4) in the high-normal range.

RESULTS

Compared with controls, hypothyroid patients exhibited left ventricular diastolic dysfunction, impaired exercise capacity, and increased intima-media thickness. At multiple regression analysis, the number of episodes of plasma TSH levels less than 0.5 mU/liter and greater than 4.0 mU/liter from the age of 1 yr onward, and mean TSH plasma levels during puberty were independent predictors of diastolic filling and cardiopulmonary performance indexes (multiple r values: 0.61-0.75).

CONCLUSIONS

Long-term levothyroxine treatment in young adults with congenital hypothyroidism is associated with impaired diastolic function and exercise capacity and increased intima-media thickness.