Reproducibility of the six-minute walking test in patients with chronic congestive heart failure: practical implications

Prognostic Value of Hemodynamic Gain Index in Patients With Heart Failure With Reduced Ejection Fraction

BACKGROUND

Assessment of functional capacity in patients with heart failure with reduced ejection fraction (HFrEF) is essential for risk stratification, and it traditionally relied on cardiopulmonary exercise testing (CPET)-derived peak oxygen consumption (peak Vo2).

OBJECTIVES

This study sought to investigate the prognostic value of alternative nonmetabolic exercise testing parameters in a contemporary cohort with HFrEF.

METHODS

Medical records of 1,067 consecutive patients with chronic HFrEF who underwent CPET from December 2012 to September 2020 were reviewed for a primary outcome that was a composite of all-cause mortality, left ventricular assist device implantation, and/or heart transplantation. Multivariable Cox regression and log-rank testing were used to determine prognostic values of various exercise testing variables.

RESULTS

The primary outcome was identified in 331 of 954 patients (34.7%) of the HFrEF cohort (median follow-up time, 946 days). After adjustment for demographics, cardiac parameters, and comorbidities, higher hemodynamic gain index (HGI) and peak rate-pressure product (RPP) were associated with greater event-free survival (adjusted HR per doubling: 0.76 and 0.36; 95% CI: 0.67-0.87 and 0.28-0.47; all P < 0.001, respectively). Moreover, HGI (area under the curve [AUC]: 0.69; 95% CI: 0.65-0.72) and peak RPP (AUC: 0.71; 95% CI: 0.68-0.74) were comparable to the standard peak Vo2 (AUC: 0.70; 95% CI: 0.66-0.73; P for comparison = 0.607 and 0.393, respectively) for primary outcome discrimination.

CONCLUSIONS

HGI and peak RPP show good correlation with peak Vo2 in terms of prognostication and outcome discrimination in patients with HFrEF and may serve as suitable alternatives to CPET-derived prognostic variables.

Walking capacity and its association with quality of life among children with down syndrome in Saudi Arabia

BACKGROUND

Walking ability, which has been connected to better health and independence, is one of the daily activities that is negatively impacted by Down syndrome. Thus, the objective of this study was to examine the walking capacity and its association with the quality of life of children who have Down syndrome compared to those who do not have Down syndrome in Saudi Arabia.

METHODS

For this cross-sectional study, we recruited 68 Arabic-speaking children aged 6 to 12 using a convenience sampling method from August to November 2021. Children were divided into two groups: those who do not have Down syndrome (n = 38) and those who have Down syndrome (n = 30). Children in the Riyadh region of Saudi Arabia who do not have Down syndrome were chosen randomly from two schools. Children who have Down syndrome were selected from multiple associations and centers in the same region. A 6-minute walk test was used to measure the child's walking capacity. The Arabic version of the Pediatric Quality of Life Inventory scale was used to assess the child's or parent's perceptions of the child's quality of life and its physical, emotional, social, and school functioning domains.

RESULTS

The difference in the mean 6-minute walk test scores between children who have and who do not have Down syndrome was statistically significant, with a mean difference = 105.6, 95% confidence limit = 57.2-154.0, p < .0001. The linear regression analysis after adjusting for age, height, weight, and body mass index revealed that walking capacity was found to be significantly associated with the worst score on the Pediatric Quality of Life Inventory scale (β = -2.71, SE = 0.49, p < .0001) and its domains of physical, social, and school functioning (β = -2.29, SE = 0.54, p < .0001; β = -2.40, SE = 0.58; p = .001; β = -3.71, SE = 0.56, p = .002, respectively) in children who have Down syndrome, but they had better emotional functioning than children who do not have Down syndrome.

CONCLUSIONS

Children who have Down syndrome were less able to walk and were highly associated with the worst possible quality of life, which included the lowest levels of physical, social, and school functioning. Early interventions with techniques must be developed to improve the quality of life for these children.

Fitbit Data to Assess Functional Capacity in Patients Before Elective Surgery: Pilot Prospective Observational Study

BACKGROUND

Preoperative assessment is crucial to prevent the risk of complications of surgical operations and is usually focused on functional capacity. The increasing availability of wearable devices (smartwatches, trackers, rings, etc) can provide less intrusive assessment methods, reduce costs, and improve accuracy.

OBJECTIVE

The aim of this study was to present and evaluate the possibility of using commercial smartwatch data, such as those retrieved from the Fitbit Inspire 2 device, to assess functional capacity before elective surgery and correlate such data with the current gold standard measure, the 6-Minute Walk Test (6MWT) distance.

METHODS

During the hospital visit, patients were evaluated in terms of functional capacity using the 6MWT. Patients were asked to wear the Fitbit Inspire 2 for 7 days (with flexibility of -2 to +2 days) after the hospital visit, before their surgical operation. Resting heart rate and daily steps data were retrieved directly from the smartwatch. Feature engineering techniques allowed the extraction of heart rate over steps (HROS) and a modified version of Non-Exercise Testing Cardiorespiratory Fitness. All measures were correlated with 6MWT.

RESULTS

In total, 31 patients were enrolled in the study (n=22, 71% men; n=9, 29% women; mean age 76.06, SD 4.75 years). Data were collected between June 2021 and May 2022. The parameter that correlated best with the 6MWT was the Non-Exercise Testing Cardiorespiratory Fitness index (r=0.68; P<.001). The average resting heart rate over the whole acquisition period for each participant had r=-0.39 (P=.03), even if some patients did not wear the device at night. The correlation of the 6MWT distance with the HROS evaluated at 1% quantile was significant, with Pearson coefficient of -0.39 (P=.04). Fitbit step count had a fair correlation of 0.59 with 6MWT (P<.001).

CONCLUSIONS

Our study is a promising starting point for the adoption of wearable technology in the evaluation of functional capacity of patients, which was strongly correlated with the gold standard. The study also identified limitations in the availability of metrics, variability of devices, accuracy and quality of data, and accessibility as crucial areas of focus for future studies.

The "can do, do do" concept in individuals with chronic obstructive pulmonary disease: an exploration of psychological mechanisms

Background

The “can do, do do” concept aims at identifying subgroups among persons with chronic obstructive pulmonary disease (COPD). Following a two-dimensional categorization, individuals are binarily classified with respect to their levels of physical capacity (“can’t do” or “can do”) and physical activity (“don’t do” or “do do”), resulting in four disjunct quadrants. The approach has been debated recently and the latest articles have concluded that the quadrants should be specifically examined in terms of psychological aspects of physical activity. Therefore, the goal of the present study was to explore the role of psychological variables in physical activity in the context of the “can do, do do” quadrant concept.

Methods

Within the scope of secondary data analyses of the “Stay Active After Rehabilitation” (STAR) randomized controlled trial, a total of 298 COPD rehabilitants of an inpatient pulmonary rehabilitation program were grouped into the suggested quadrants. We set fixed cut-offs at 70% of relative 6-min walking test performances for healthy individuals (physical capacity dimension) and 5.000 steps per day (physical activity dimension). Univariate and multivariate logistic regression analyses served to analyze whether depression scores, fear avoidance behaviors, disease-specific anxiety, self-concordance for physical activity, and five indicators of physical activity-related health competence (PAHCO) effectively discriminated between the “don’t do” and “do do” groups.

Results

Among persons with lower relative physical capacity, depression scores, fear avoidance behaviors, and disease-specific anxiety (univariate case) significantly differentiated between the more and the less active. Among persons with higher relative physical capacity, fear avoidance behaviors, disease-specific anxiety, as well as three PAHCO indicators (physical activity-specific self-efficacy, self-control, and affect regulation) significantly separated the more and the less active. In multivariate analyses, only fear avoidance behaviors and affect regulation discriminated among individuals with better relative physical capacity.

Conclusion

The findings identified important psychological and competence-oriented variables that explain discrepancies in the quadrant concept. Based on this, we discuss implications for physical activity promotion in individuals with COPD. Respiratory research can benefit from future studies complementing the quadrant concept through further behavioral analyses.

Trial registration Clinicaltrials.gov, ID: NCT02966561. Registered 17 November, 2016, https://clinicaltrials.gov/ct2/show/NCT02966561.

Towards a better understanding of physical activity in people with COPD: predicting physical activity after pulmonary rehabilitation using an integrative competence model

The integrative Physical Activity-related Health Competence (PAHCO) model specifies competences (movement competence, control competence, and self-regulation competence) that enable people to lead a physically active lifestyle. This longitudinal study analyses the predictive quality of a multidimensional PAHCO assessment for levels of physical activity (PA) and their relevance for quality of life in COPD patients after pulmonary rehabilitation. At the end of an inpatient pulmonary rehabilitation (T2), 350 COPD patients participating in the Stay Active after Rehabilitation (STAR) study underwent assessments, including a six-factor measurement of PAHCO. PA (triaxial accelerometry) and quality of life (Saint George's Respiratory Questionnaire) were recorded 6 weeks (T3) and 6 months (T4) after rehabilitation. Structural equation modelling (SEM) was used to regress the PAHCO assessment on PA, which should, in turn, influence quality of life. In univariable analysis, five and six factors of the PAHCO model were related to PA and quality of life, respectively. Multivariate modelling showed that the predictive analyses for the PA level were dominated by the 6-minute walking test representing movement competence (0.562 ≤ |β| ≤ 0.599). Affect regulation as an indicator of control competence co-predicted quality of life at T3 and levels of PA at T4. The PA level was, in turn, significantly associated with patients' quality of life (0.306 ≤ |β| ≤ 0.388). The integrative PAHCO model may be used as a theoretical framework for predicting PA in COPD patients following pulmonary rehabilitation. The results improve our understanding of PA behaviour in COPD patients and bear implications for person-oriented PA promotion.

Interval training early after heart failure decompensation is safe and improves exercise tolerance and quality of life in selected patients

Aims To evaluate safety and efficacy of moderate intensity interval exercise training early after heart failure decompensation on exercise tolerance and health-related quality of life (HRQoL). Methods and results This is a prospective randomized controlled study. We screened 234 consecutive patients admitted with decompensated heart failure; 46 patients (42 men/4 women; 61 ± 12 years of age) were randomized to a moderate intensity aerobic interval training ( n = 24) or to a control group ( n = 22). Patients underwent cardiopulmonary exercise testing, echocardiography and Minnesota Living with Heart Failure questionnaire (MLHFQ) at baseline, after three weeks and after three months. After three weeks, peak-VO₂ increased by 17% in the training group ( p = 0.003) with further increase by 10% after three months ( p < 0.001) but did not change significantly in controls. MLHFQ score improved after three weeks, with better results in the training group (from 64.6 ± 15.6 to 30.8 ± 12.9, p < 0.001). After three months, MLHFQ further improved in the exercise training group, but not in controls. Left ventricular ejection fraction was not significantly different between the two groups at baseline and after three months. No serious adverse events related to exercise testing or training were observed. Conclusions Interval exercise training early after an episode of heart failure decompensation is safe and effective in improving exercise tolerance and health-related quality of life in selected patients after achievement of clinical stability. Positive effects remained sustained after three months. Further studies are needed to define role and indications for interval exercise training early after heart failure decompensation.

Exercise- and Psychosocial-Based Interventions to Improve Daily Activity in Heart Failure: A Pilot Study

In individuals with heart failure (HF), low daily activity is associated with a poorer prognosis. The purpose of this pilot study was to investigate the effects of two home-based interventions on the primary HF-related outcome of daily activity and secondary outcomes of exercise tolerance, HF-related health status, and lower extremity functional strength in 16 patients with HF and implanted Medtronic implantable cardioverter defibrillator and cardiac resynchronization devices using a single-blind, randomized controlled pilot trial. Interventions were either daily activity feedback and encouragement or health coaching and home-based exercise. There were no significant differences in primary or secondary outcomes either between or within groups. Three subjects in each treatment group improved in two or more secondary outcomes, and only one improved in daily activity. Although the present pilot study incorporated both exercise and psychosocial components in the intervention, there was no effect on daily activity, perhaps because readiness for behavioral change was not accounted for either in group stratification/allocation or inclusion criteria.

EFEITOS DO TREINAMENTO FÍSICO NO ENDOTÉLIO APÓS CIRURGIA DE REVASCULARIZAÇÃO

Introdução A cirurgia de revascularização do miocárdio (CRM) é uma das mais frequentes cirurgias realizadas em todo o mundo, muitos estudos vêm relatando os benefícios do treinamento físico para a melhora da capacidade funcional, porém há poucos estudos sobre os efeitos na função endotelial vascular. Objetivo Analisar os efeitos do treinamento físico sobre a função endotelial vascular em pacientes submetidos à CRM, isoladamente na fase tardia da reabilitação após seis meses de programa de reabilitação cardíaca (PCR). Métodos Foram incluídos pacientes que haviam sido submetidos à CRM no período máximo de um ano após a cirurgia. O PRC foi empregado durante seis meses consecutivos, com três sessões semanais. Todos os pacientes realizaram exames laboratoriais, teste de força muscular de uma repetição máxima (1-RM) para os membros superiores e inferiores, teste de caminhada de 6 min (TC6M) e avaliação da função endotelial através da técnica de vasodilatação mediada pelo fluxo. Resultados Onze pacientes iniciaram o PRC, porém nove pacientes o completaram. A média de idade foi de 66 anos (50 a 82 anos) e o sexo masculino foi predominante (55,6%). Houve mudanças significativas nos exames laboratoriais bioquímicos: aumento do colesterol total (Basal: 162 ± 31mg/dL vs. 195 ± 39mg/dL; P=0,012) e diminuição da hemoglobina glicada (Basal: 6,74 ± 1,64% vs. 6,26 ± 1,62%; P=0,028). A força muscular aumentou significativamente nos membros superiores e inferiores (P=0,030 e P=0,038, respectivamente); no TC6M observou-se um aumento significativo de 20% na distância percorrida (P=0,020) após seis meses consecutivos de treinamento e houve uma melhora na vasodilatação mediada pelo fluxo (Basal: 6,35 ± 3,92% vs. 6 meses: 9,90 ± 4,19%; P=0,026). Conclusão O treinamento combinado realizado em seis meses ajudou a melhorar a função endotelial e a capacidade funcional de pacientes sedentários que foram submetidos à CRM na fase tardia da reabilitação.

Accuracy and Usability of a Self-Administered 6-Minute Walk Test Smartphone Application

BACKGROUND

The 6-minute walk test (6MWT) independently predicts congestive heart failure severity, death, and heart failure hospitalizations, but must be administered in clinic by qualified staff on a premeasured course. As part of the Health eHeart Study, we sought to develop and validate a self-administered 6MWT mobile application (SA-6MWTapp) for independent use at home by patients.

METHODS AND RESULTS

We performed a validation study of an SA-6MWTapp in 103 participants. In phase 1 (n=52), we developed a distance-estimation algorithm for the SA-6MWTapp by comparing step counts from an Actigraph and measured distance on a premeasured 6MWT course with step counts and estimated distance obtained simultaneously from our SA-6MWTapp (best estimation algorithm, r=0.89 [95% confidence interval 0.78-0.99]). In phase 2, 32 participants (including those with congestive heart failure and pulmonary hypertension) used the SA-6MWTapp independently in clinic, and the distance estimated by the SA-6MWTapp was compared with the measured distance (r=0.83 [95% confidence interval 0.79-0.92]). In phase 3, 19 patients with congestive heart failure and pulmonary hypertension consecutively enrolled from clinic performed 3.2±1 SA-6MWTapp tests per week at home over 2 weeks. Distances estimated from the SA-6MWTapp during home 6MWTs were highly repeatable (coefficient of variation =4.6%) and correlated with in-clinic-measured distance (r=0.88 [95% confidence interval 0.87-0.89]). Usability surveys performed during the second (in-clinic) and third (at-home) phases demonstrated that the SA-6MWTapp was simple and easy to use independently.

CONCLUSIONS

An SA-6MWTapp is easy to use and yields accurate repeatable measurements in the clinic and at home.

Capacidade funcional como preditor de qualidade de vida na insuficiência cardíaca

INTRODUÇÃO: A insuficiência cardíaca (IC) prejudica a qualidade de vida (QV), enquanto a reabilitação cardiopulmonar e metabólica (RCPM) de pacientes com a síndrome proporciona melhora da capacidade funcional (CF) e da qualidade de vida. OBJETIVOS: Determinar a relação dos domínios da QV com a CF de pacientes com IC, assim como propor pontos de corte dos domínios da QV por meio da CF. MATERIAIS E MÉTODOS: Avaliou-se 57 pacientes com IC, classe funcional II e III, sendo 37 ingressantes (GI) no programa de RCPM e 20 participantes (GP) com mais de três meses de programa. A QV foi avaliada pelo questionário de Minnesota por meio dos domínios físicos, emocionais e dimensões gerais. A CF foi determinada por meio do teste de caminhada de seis minutos (TC6'), tendo pontos de corte definidos conforme proposto na literatura. Utilizou-se teste t de Student, correlação de Pearson e análise da curva ROC para responder aos objetivos da pesquisa, considerando significância de 5%. RESULTADOS: Participantes da RCPM apresentaram melhores escores da QV quando comparados aos ingressantes. Correlações significativas foram observadas entre o domínio emocional e TC6' para ambos os grupos. Verificou-se pontos de corte significativos dos domínios da QV advindos da CF, com destaque ao domínio emocional (sensibilidade/especificidade) para ambos os grupos. CONCLUSÃO: Os portadores de IC com mais de três meses de RCPM apresentaram melhor QV e capacidade funcional do que os iniciantes. O domínio emocional do questionário de Minnesota se mostrou um bom preditor de ponto de corte da capacidade funcional.

Clinically meaningful change estimates for the six-minute walk test and daily activity in individuals with chronic heart failure

PURPOSE

The purpose of the present pilot study was to provide a preliminary estimate of the minimum detectable difference (MDD) and minimum clinically important difference (MCID) of the six-minute walk test (6MWT) and daily activity in outpatients with chronic heart failure (CHF).

METHODS

A convenience sample of 22 adults with stable New York Heart Association Functional Class II and III CHF performed two baseline 6MWTs separated by 30 minutes of rest. Subjects then wore a triaxial accelerometer for 7 days to monitor daily activity. After 7 weeks of usual care, subjects again wore the accelerometer for 7 days and then returned to the clinic to complete the Global Rating of Change Scale (GRS) with regard to their heart disease and perform another set of 6MWTs. For the 6MWT, the MDD was calculated using the two baseline 6MWT distances. For daily activity, the MDD was calculated using two methods: (1) day-to-day test-retest reliability during baseline monitoring, and (2) baseline to follow-up test-retest reliability in those who reported no change on the GRS. The MCID for the 6MWT and daily activity was calculated using the mean and 95% confidence interval (CI95%) for those subjects who reported 'improvement' on the GRS.

RESULTS

The MDD at the CI95% for the 6MWT was 32.4 meters. The MCID for the 6MWT was 30.1 (CI95% 20.8, 39.4) meters. The MDD for daily activity was 5,909 vector magnitude units (VMU·hr.(-1)) The MCID for daily activity was 1,337 VMU·hr.(-1) There was good alignment of the MDD and MCID for the 6MWT, suggesting that clinically meaningful change is approximately 32 meters. However, the calculated MCID was substantially less than measurement error as represented by the MDD, indicating that the MCID was underestimated in this sample or that daily activity may be robust to change in overall disease status.

Reliability, agreement, and responsiveness of a 6-minute walk/run test in patients with heart disease

BACKGROUND

The 6-minute walk test (6 MWT) is widely used to assess exercise tolerance in cardiac rehabilitation (CR). However, previous research shows it to be insufficiently responsive, especially for patients with a relatively high maximal exercise tolerance at baseline. We therefore designed a 6-minute walk/run test (6 MWRT), which has the same duration as the 6 MWT but allows running. The objective of this study was to determine the test-retest reproducibility and responsiveness of this 6 MWRT.

DESIGN

Responsiveness was investigated in a prospective cohort study among a group of patients entering CR at Maastricht University Medical Center, with a cross-sectional part to assess the test-retest reproducibility.

METHODS

Test-retest reproducibility (reliability and agreement) was investigated using the intraclass correlation (ICC) and a Bland-Altman plot of two measurements implemented in the first week of rehabilitation. Responsiveness of the 6 MWT and the 6 MWRT was calculated using the standard response mean (SRM) over a 6-week period.

RESULTS

The first reproducibility analysis included 34 patients, the second 22 patients. The ICCs were 0.935 and 0.906, respectively, with limits of agreement of ± 79 and ± 61 m. The responsiveness analysis included 27 patients. The SRM values were 0.83 for the 6 MWT and 0.71 for the 6 MWRT.

CONCLUSIONS

Although the 6 MWRT is a reproducible test in CR, its responsiveness is not superior to that of the 6 MWT. We therefore prefer the conventional 6 MWT as an evaluative measurement in CR and advise against using the 6 MWRT as (evaluative) measurement in CR for this purpose.

The 6-min walk test: is it an effective method for evaluating heart failure therapies?

The 6-min walk (6MW) is a self-paced test for measuring functional capacity. Lower 6MW distances have been associated with adverse outcomes in patients with heart failure. The purpose of this article is to describe the history of the 6MW test and to evaluate its reliability, validity, and predictive value as well as the responsiveness of the test to therapies. In the literature we reviewed, reliability was affected by several factors including learning effects and protocol deviations. The 6MW distance was moderately correlated with peak oxygen consumption derived from cardiopulmonary exercise stress testing. In some studies the 6MW distance was predictive of hospitalization and mortality. In pharmacological and cardiac resynchronization trials the 6MW distance did not consistently detect clinical improvements. Despite limitations, the 6MW test is a viable alternative to stress testing for objectively evaluating functional capacity in some settings. We provide recommendations for using the 6MW test in future studies.

Repeat six-minute walk tests in patients with chronic heart failure: are they clinically necessary?

BACKGROUND

Owing to a reported learning effect in patients with chronic cardiopulmonary disease, performance of at least two six-minute walk tests (6MWT) are recommended as standard practice. Patients with chronic heart failure (CHF) are typically elderly and frail and it is unknown whether current guidelines are practical in a clinical setting.

AIMS

The aim of this study was to determine whether repeat performance of 6MWTs in patients with CHF is related to between-test interval or baseline performance.

METHODS

This was a multisite observational study enrolling participants entering into heart failure rehabilitation programmes. Participants performed two 6MWTs with randomly allocated inter-test intervals between 15 and 90 minutes. Distance walked in the second test was compared with the first test using a paired t test.

RESULTS

Eighty-eight participants (45 females, age 65 ± 14 years) with stable CHF were enrolled. Mean distance walked increased from 301 metres in test 1 to 313 metres in test 2 (p < 0.001). No significant change was recorded between test 1 and test 2 for those whose baseline distance was <300 metres. The interval between tests had no significant effect on the distance walked.

CONCLUSION

The change in 6MWT distance was significantly associated with better baseline performance but not with the interval between tests.

Usefulness of echo-guided cardiac resynchronization pacing in patients undergoing "ablate and pace" therapy for permanent atrial fibrillation and effects of heart rate regularization and left ventricular resynchronization

An acute comparative study of right ventricular (RV) pacing and echocardiographically guided cardiac resynchronization pacing (CRP) was performed in patients who underwent "ablate and pace" therapy for permanent atrial fibrillation. It was hypothesized that optimized CRP guided by tissue Doppler echocardiography would exert an additive beneficial hemodynamic effect to that of rate regularization achieved through atrioventricular junction ablation. An acute intrapatient comparison of echocardiographic parameters was performed between baseline preablation values and RV pacing and CRP (performed <24 hours after ablation) in 50 patients. Optimized CRP configuration was defined as the modality of pacing corresponding to that of the shortest intra-left ventricular (LV) delay among simultaneous biventricular pacing, sequential biventricular pacing, and single-chamber pacing. The intra-LV delay was defined as the difference between the longest and the shortest activation time in the six basal segments of the left ventricle. Compared with preablation measures, the ejection fraction increased by 10.8% during RV pacing (19% in patients with intra-LV delays <47.5 ms and 3% in those with intra-LV delays >47.5 ms). Compared with RV pacing, CRP caused a 9.2% increase in the ejection fraction, a 6.8% decrease in LV systolic diameter, and a 17.3% decrease in mitral regurgitation area; LV dyssynchrony was reduced from 52 +/- 27 to 21 +/- 12 ms. Similar results were observed in patients with and without depressed systolic function and in patients with and without left bundle branch block. In conclusion, rate regularization achieved through atrioventricular junction ablation and RV pacing provides a favorable hemodynamic effect that is inversely related to the level of LV dyssynchrony. Minimizing LV dyssynchrony by means of optimized CRP yields an additional important benefit.

Six minute walk test: a simple and useful test to evaluate functional capacity in patients with heart failure

In heart failure survival is closely related to functional capacity. Peak O2 consumption at cardiopulmonary exercise test (CPET) is considered the gold standard for the evaluation of exercise tolerance. Since >70% of patients with heart failure, usually elderly or with significant comorbidities, are referred to Departments of Internal Medicine where facilities for cardiopulmonary test are rarely available, CPET may be performed in <5% of the patients. Six-minute walk test (6MWT) has been proposed as a simple, inexpensive, reproducible alternative to CPET. The 6MWT reproduces the activity of daily life and this is particularly relevant in elderly patients who usually develop symptoms below their theoretical maximal exercise capacity. Despite some limits 6MWT is attractive for patients referred to Departments of Internal Medicine allowing an objective evaluation of exercise tolerance, a better prognostic evaluation and a guide to evaluate response to medical treatment.

Effect of penetrating trunk trauma on the recovery of adult survivors: a pilot study

Gunshot and/or stab wounds to the trunk are injuries seen in South African hospitals. Patients are managed in the intensive care unit. Prolonged mechanical ventilation with immobilization results in some degree of muscle dysfunction. Our goal was to determine if patients recover adequately spontaneously following critical illness. No formal rehabilitation programmes exist in South Africa for these patients following discharge. A prospective, observational study was conducted. Patients were recruited from three ICUs in Johannesburg. Lung function tests, dynamometry, quality of life, 6-minute-walk, and oxygen uptake tests were performed over 6 months following discharge from the hospital. The control group consisted of existing data for healthy volunteers. Distance walked during 6-minute-walk test was significantly reduced for the study group compared to the control group (1 month [p = 0.00251]; 6 months [p = 0.0355]). At 1 month there was a significant reduction in quadriceps and triceps strength for the study group compared to the control group (p = 0.0089; p = 0.0246, respectively). Quadriceps strength remained significantly reduced for the study group (3 months [p = 0.0489]). No difference in muscle strength was detected between the groups at 6 months. Actual and predicted residual volumes differed significantly for the study group (1 month [p = 0.0034]; 6 months [p = 0.0157]). A trend of muscle weakness (to 3 months), poor exercise capacity, and abnormal lung volumes was identified. A formal rehabilitation programme may be needed to address these disabilities.

Test-retest reliability and minimal detectable change on balance and ambulation tests, the 36-item short-form health survey, and the unified Parkinson disease rating scale in people with parkinsonism

BACKGROUND AND PURPOSE

Distinguishing between a clinically significant change and change due to measurement error can be difficult. The purpose of this study was to determine test-retest reliability and minimal detectable change for the Berg Balance Scale (BBS), forward and backward functional reach, the Romberg Test and the Sharpened Romberg Test (SRT) with eyes open and closed, the Activities-specific Balance Confidence (ABC) Scale, the Six-Minute Walk Test (6MWT), comfortable and fast gait speed, the Timed "Up & Go" Test (TUG), the Medical

OUTCOMES

Study 36-Item Short-Form Health Survey (SF-36), and the Unified Parkinson Disease Rating Scale (UPDRS) in people with parkinsonism.

SUBJECTS

Thirty-seven community-dwelling adults with parkinsonism (mean age=71 years) participated. The Hoehn and Yahr Scale median score of 2 was on the lower end of the scale; however, the scores ranged from 1 to 4.

METHODS

Subjects were tested twice by the same raters, with 1 week between tests. Test-retest reliability was calculated using intraclass correlation coefficients (ICCs). Minimal detectable change was calculated using a 95% confidence interval (MDC(95)).

RESULTS

The ICCs for test-retest reliability were above .90 for the BBS, ABC Scale, SRT with eyes closed, 6MWT, and comfortable and fast gait speeds. The MDC(95) values for those functional tests were: BBS=5/56, ABC Scale=13%, SRT with eyes closed=19 seconds, 6MWT=82 m, comfortable gait speed=0.18 m/s, and fast gait speed=0.25 m/s. The ICCs for test-retest reliability of SF-36 scores were above .80, with the exception of the social functioning subscale. The MDC(95) values for the SF-36 ranged between 19% and 45%. The MDC(95) values for the UPDRS Activities of Daily Living section, Motor Examination section, and total scores were 4/52, 11/108, and 13/176, respectively.

DISCUSSION AND CONCLUSION

Minimal detectable change values are useful to therapists in rehabilitation and wellness programs in determining whether change during or after intervention is clinically significant. High test-retest reliability of scores for the BBS, ABC Scale, SRT with eyes closed, 6MWT, and gait speed make them trustworthy functional assessments in people with parkinsonism. The SF-36 and UPDRS provide quality-of-life and disease severity rating values in the ongoing assessment of people with parkinsonism.

Reproducibility of the self-controlled six-minute walking test in heart failure patients

INTRODUCTION

The six-minute walk test (6WT) has been proposed to be a submaximal test, but could actually demand a high level of exercise intensity from the patient, expressed by a respiratory quotient >1.0, following the guideline recommendations. Standardizing the 6WT using the Borg scale was proposed to make sure that all patients undergo a submaximal walking test.

PURPOSE

To test the reproducibility of the six-minute treadmill cardiopulmonary walk test (6CWT) using the Borg scale and to make sure that all patients undergo a submaximal test.

METHODS

Twenty-three male heart failure patients (50+/-9 years) were included; these patients had both ischemic (5) and non-ischemic (18) heart failure with a left ventricle ejection fraction of 23+/-7%, were diagnosed as functional class NYHA II-III and were undergoing optimized drug therapy. Patients were guided to walk at a pace between "relatively easy and slightly tiring" (11 and 13 on Borg scale). The 6CWT using the Borg scale was performed two times on a treadmill with zero inclination and patient control of speed with an interval of 24 hours. During the sixth minute, we analyzed ventilation (VE, L/min), respiratory quotient, Oxygen consumption (VO2, ml/kg/min), VE/VCO2 slope, heart rate (HR, bpm), systolic blood pressure (SBP, mmHg), diastolic (DBP, mmHg) blood pressure and distance.

RESULTS

The intraclass correlation coefficients at the sixth minute were: HR (r i=0.96, p<0.0001), VE (r i=0.84, p<0.0001), SBP (r i=0.72, p=0.001), distance (r i=0.88, p<0.0001), VO2 (r i=0.92, p<0.0001), SlopeVE/VCO2 (r i=0.86, p<0.0001) and RQ<1 (r i=0.6, p=0.004).

CONCLUSION

Using the 6CWT with the Borg scale was reproducible, and it seems to be an appropriate method to evaluate the functional capacity of heart failure patients while making sure that they undergo a submaximal walking test.

The 6-min walking test early after cardiac surgery. Reference values and the effects of rehabilitation programme

BACKGROUND

The 6-min walking test (6MWT) is a simple test, which does not require expensive equipment or advanced training. It has been used in heart failure patients to assess exercise tolerance, the effects of therapy and prognosis. Accordingly, post-surgical cardiac rehabilitation may be a potential field of application of this test.

MATERIALS AND METHOD

One thousand three hundred seventy patients (70% males, mean age 64+/-10 years), consecutively admitted for intensive cardiac rehabilitation, underwent 6MWT within 15 days after different types of cardiac surgery (67% coronary artery bypass graft (CABG), 25% valve replacement, 4% both, 4% other). The 6MWT was repeated in a subgroup of 348 patients after 15+/-3 days of an in-hospital cardiac rehabilitation programme.

RESULTS

6MWT (expressed as absolute value in metres and as a percentage of the predicted value) was well tolerated in all patients. The mean distance walked in 1370 patients was 304+/-89 m (corresponding to 58+/-15% of the predicted value). Distances walked were significantly shorter in older patients than younger (p<0.05) and in women compared to men (251+/-78 m, 53+/-15%, vs 328+/-34 m, 60+/-14%, p<0.001). Furthermore, the absolute distance walked in 6 min was significantly shorter in diabetics compared to non-diabetics (283+/-85 m vs 302+/-87 m, p=0.001) and in no CABG compared to CABG patients (285+/-91 m vs 303+/-84 m, p<0.001); no relation was found between distance walked and left ventricular ejection fraction (p=0.5). Gender, age, comorbidities and type of surgery were independently associated with 6MWT in the multivariate model. In the subgroup of patients repeating the 6MWT after the rehabilitation programme, the distance walked significantly increased (from 281+/-90 m, 51+/-76%, to 411+/-107 m, 77+/-81%, p<0.001). The extent of improvement observed was similar according to sex, age, presence/absence of diabetes and type of surgery.

CONCLUSIONS

Our data suggest that 6MWT is feasible and well tolerated in adult and older patients shortly after uncomplicated cardiac surgery and provides reference values for distance walked after cardiac surgery in this population.

How to diagnose diastolic heart failure: a consensus statement on the diagnosis of heart failure with normal left ventricular ejection fraction by the Heart Failure and Echocardiography Associations of the European Society of Cardiology

Diastolic heart failure (DHF) currently accounts for more than 50% of all heart failure patients. DHF is also referred to as heart failure with normal left ventricular (LV) ejection fraction (HFNEF) to indicate that HFNEF could be a precursor of heart failure with reduced LVEF. Because of improved cardiac imaging and because of widespread clinical use of plasma levels of natriuretic peptides, diagnostic criteria for HFNEF needed to be updated. The diagnosis of HFNEF requires the following conditions to be satisfied: (i) signs or symptoms of heart failure; (ii) normal or mildly abnormal systolic LV function; (iii) evidence of diastolic LV dysfunction. Normal or mildly abnormal systolic LV function implies both an LVEF > 50% and an LV end-diastolic volume index (LVEDVI) <97 mL/m(2). Diagnostic evidence of diastolic LV dysfunction can be obtained invasively (LV end-diastolic pressure >16 mmHg or mean pulmonary capillary wedge pressure >12 mmHg) or non-invasively by tissue Doppler (TD) (E/E' > 15). If TD yields an E/E' ratio suggestive of diastolic LV dysfunction (15 > E/E' > 8), additional non-invasive investigations are required for diagnostic evidence of diastolic LV dysfunction. These can consist of blood flow Doppler of mitral valve or pulmonary veins, echo measures of LV mass index or left atrial volume index, electrocardiographic evidence of atrial fibrillation, or plasma levels of natriuretic peptides. If plasma levels of natriuretic peptides are elevated, diagnostic evidence of diastolic LV dysfunction also requires additional non-invasive investigations such as TD, blood flow Doppler of mitral valve or pulmonary veins, echo measures of LV mass index or left atrial volume index, or electrocardiographic evidence of atrial fibrillation. A similar strategy with focus on a high negative predictive value of successive investigations is proposed for the exclusion of HFNEF in patients with breathlessness and no signs of congestion. The updated strategies for the diagnosis and exclusion of HFNEF are useful not only for individual patient management but also for patient recruitment in future clinical trials exploring therapies for HFNEF.

Effects of continuous positive airway pressure on pulmonary function and exercise tolerance in patients with congestive heart failure

STUDY OBJECTIVES

Continuous positive airway pressure (CPAP) has been used to improve cardiopulmonary function and reduce pulmonary edema symptoms in patients with congestive heart failure (CHF). The objective of this study was to evaluate the efficacy of CPAP therapy on pulmonary function and exercise tolerance in patients with CHF.

DESIGN

Prospective blind randomized clinical study.

PARTICIPANTS

Twenty-four patients with class II or III CHF and dilated cardiomyopathy were randomly assigned to 30 min of CPAP therapy and respiratory exercises (CPAP group) or respiratory exercise only (control group) once a day for 14 days.

MEASUREMENTS AND RESULTS

Evaluation of pulmonary function was performed measuring FEV1 and FVC. Exercise tolerance was assessed measuring the distance walked during the 6-min walking test (6MWT). These parameters were measured before treatment and 4 days, 9 days, and 14 days later. CPAP therapy caused a progressive increase (p < 0.05) in both FVC (maximum of 16% after 9 days) and FEV1 (maximum of 14% after 14 days) compared to basal values, without significant changes in the control group. The 6MWT showed a progressive improvement in the distance walked in the CPAP group, reaching approximately 28% above the basal values in the CPAP group and without significant changes in the control group.

CONCLUSIONS

These data show that the use of CPAP therapy for 2 weeks on a daily basis is able to enhance pulmonary function and consequently improve the tolerance to physical activities in patients with CHF. The clinical implication of this finding is that CPAP therapy could potentially be used as an adjunct to the treatment of CHF patients.

Four-Year Efficacy of Cardiac Resynchronization Therapy on Exercise Tolerance and Disease Progression

OBJECTIVES

The goal of this study was to investigate the effects of cardiac resynchronization therapy (CRT) in heart failure patients with permanent atrial fibrillation (AF) and the role of atrioventricular junction (AVJ) ablation.

BACKGROUND

Cardiac resynchronization therapy has been proven effective in heart failure patients with sinus rhythm (SR). However, little is known about the effects of CRT in heart failure patients with permanent AF.

METHODS

Efficacy of CRT on ventricular function, exercise performance, and reversal of maladaptive remodeling process was prospectively compared in 48 patients with permanent AF in whom ventricular rate was controlled by drugs, thus resulting in apparently adequate delivery of biventricular pacing (>85% of pacing time), and in 114 permanent AF patients, who had undergone AVJ ablation (100% of resynchronization therapy delivery). The clinical and echocardiographic long-term outcomes of both groups were compared with those of 511 SR patients treated with CRT.

RESULTS

Both SR and AF groups showed significant and sustained improvements of all assessed parameters (model p < 0.001 for all parameters). However, within the AF group, only patients who underwent ablation showed a significant increase of ejection fraction (p < 0.001), reverse remodeling effect (p < 0.001), and improved exercise tolerance (p < 0.001); no improvements were observed in AF patients who did not undergo ablation.

CONCLUSIONS

Heart failure patients with ventricular conduction disturbance and permanent AF treated with CRT showed large and sustained long-term (up to 4 year) improvements of left ventricular function and functional capacity, similar to patients in SR, only if AVJ ablation was performed.

Short-Term Change in Distance Walked in 6 Min Is an Indicator of Outcome in Patients With Chronic Heart Failure in Clinical Practice

OBJECTIVES

The purpose of this study was to investigate the prognostic value of change in distance walked in 6 min in chronic heart failure (CHF).

BACKGROUND

The strongest indication for the 6-min walking test (6MWT) is for measuring the response to therapeutic interventions in patients with CHF. Whether the increase in distance walked after a therapeutic intervention translates into improved clinical outcome is largely unknwon.

METHODS

We studied 476 CHF patients with left ventricular systolic dysfunction who were referred to our institution for adjustment of heart failure therapy because of persisting or worsening symptoms. Adjustment of therapy involved four classes of drugs: angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, beta-blockers, loop diuretics, and aldosterone antagonists. A standardized 6MWT was performed at baseline and at discharge.

RESULTS

After 15.2 +/- 8 days, the distance walked increased from 326 +/- 107 m to 408 +/- 109 m (+25%; p = 0.001). During a mean follow-up of 23.9 months, 94 patients died and 12 patients underwent cardiac transplantation. Among a set of variables, New York Heart Association functional class (p = 0.02), serum creatinine concentration (p = 0.01), left ventricular ejection fraction (p = 0.002), distance walked at baseline (p = 0.0002), and change in distance walked (p = 0.002) were significant independent predictors of survival. When the patients were divided into two subgroups according to the median value of the distance walked at baseline, the increase in walking distance was significantly associated with survival only in the subgroup of patients who walked <340 m at baseline.

CONCLUSIONS

Our data indicate that repeating a 6MWT after drug intervention provides independent prognostic information in CHF patients with more compromised exercise capacity.

Effect of step-synchronized vibration stimulation of soles on gait in Parkinson's disease: a pilot study

BACKGROUND

Previous studies have suggested that impaired proprioceptive processing in the striatum may contribute to abnormal gait in Parkinson's disease (PD).

METHODS

This pilot study assessed the effects of enhanced proprioceptive feedback using step-synchronized vibration stimulation of the soles (S-VS) on gait in PD. S-VS was used in 8 PD subjects (3 women and 5 men, age range 44-79 years, on medication) and 8 age-matched healthy subjects (5 women and 3 men). PD subjects had mild or moderate gait impairment associated with abnormal balance, but they did not have gait freezing. Three vibratory devices (VDs) were embedded in elastic insoles (one below the heel and two below the forefoot areas) inserted into the shoes. Each VD operates independently and has a pressure switch that activates the underlying vibratory actuator. The VD delivered the 70-Hz suprathreshold vibration pulse upon touch by the heel or forefoot, and the vibration pulse was deactivated upon respective push-offs. Six-minute hallway walking was studied with and without S-VS. Gait characteristics were measured using the force-sensitive foot switches. The primary outcome was the stride variability expressed as a coefficient of variation (CV), a measure of gait steadiness. Secondary outcome measures were walking distance and speed, stride length and duration, cadence, stance, swing and double support duration, and respective CVs (if applicable).

RESULTS

The walking speed (p < 0.04) and the CV of the stride interval (p < 0.02) differed between the groups and S-VS conditions. In the PD group, S-VS decreased stride variability (p < 0.002), increased walking speed (p < 0.0001), stride duration (p < 0.01), stride length (p < 0.0002), and cadence (p < 0.03). In the control group, S-VS decreased stride variability (p < 0.006) and increased gait speed (p < 0.03), but other locomotion parameters were not significantly altered.

CONCLUSION

Augmented sensory feedback improves parkinsonian gait steadiness in the short-term setting. Because the suprathreshold stimulation prevented blinding of subjects, the learning effect and increased attention can be a confounding factor underlying results. Long-term studies are needed to establish the clinical value of the S-VS.

Short-term improvement in submaximal exercise capacity by optimized therapy with ACE inhibitors and beta blockers in heart failure patients is associated with restoration of peripheral endothelial function

BACKGROUND

Improved exercise capacity in chronic heart failure (CHF) has been attributed to restoration of endothelial function. ACE inhibitors as well as beta blockers have previously been shown to enhance endothelial function and exercise capacity. The aim of this study was to determine whether short-term improvement in submaximal exercise capacity induced by optimized therapy with ACE inhibitors in combination with beta blockers is associated with restoration of endothelial function in CHF patients.

METHODS

Thirty-three patients with CHF were evaluated: six-minute walk test, NYHA class, brain natriuretic peptide (BNP), big Endothelin-1 (bigET-1) and flow-mediated vasodilation (FMD) of the brachial artery were assessed at baseline and after a 3-month period of optimized neurohormonal therapy. Two groups were formed retrospectively based on the changes in submaximal exercise capacity (responders and non-responders).

RESULTS

Optimization of neurohormonal therapy was comparable between groups. Responders (n=17) revealed a significant increase in walking distance (304+/-109 to 441+/-75 m; p<0.01), which was paralleled by a decrease in NYHA class (2.7+/-0.6 to 2.0+/-0.4; p<0.01), BNP (484+/-454 to 243+/-197 pg/ml; p<0.01), and bigET-1 (2.0+/-0.9 vs. 1.5+/-0.6 fmol/ml; p=0.04). By contrast, the latter variables did not change in non-responders. Improvement in functional capacity in responders was associated with an increase in FMD (8.2+/-3.9% to 11.0+/-5.6%; p<0.05). Increments in FMD were directly correlated with increases in walking distance (r=0.34; p<0.05).

CONCLUSION

Short-term improvement of submaximal exercise capacity in CHF patients following optimized therapy with ACE inhibitors and beta blockers is associated with restoration of endothelial function in conduit arteries.

The reproducibility and sensitivity of the 6-min walk test in elderly patients with chronic heart failure

AIMS

The 6-min walk test (6-MWT) is used to estimate functional capacity. However, in elderly patients with chronic heart failure (CHF): (i) 1 year reproducibility of the 6-MWT; (ii) sensitivity of the 6-MWT to self-perceived changes in symptoms of heart failure; and (iii) implications for patient numbers required for studies using the 6-MWT as an endpoint have not been described.

METHODS AND RESULTS

One thousand and seventy-seven patients with CHF, aged>60, with NYHA Class > or =II were recruited. Heart failure symptom assessment was determined using a questionnaire related to aspects of physical function, and patients performed a baseline 6-MWT, with follow-up 1 year later. Seventy-four patients with unchanged symptoms had an unchanged 6-MWT distance, with an overall intraclass correlation coefficient of 0.80 (95% CI=0.69-0.87). Four hundred and twenty-three patients reported an improvement in symptoms during follow-up. There was a negative correlation (r=-0.55; P=0.0001) between Delta symptoms and Delta 6-MWT (i.e. a reduced 6-MWT distance is associated with reduced symptom severity at follow-up). Five hundred and sixteen patients reported worsening symptoms of heart failure, a moderate inverse correlation (r=-0.53; P=0.0001) was displayed between Delta symptoms and Delta 6-MWT. For all patients, irrespective of symptom status, a high inverse correlation (r=-0.75; P=0.0001) was evident. On the basis of the data for patients with unchanged symptoms, it is calculated that to detect an increase in 6-MWT of 50 m, with 90% power, a study size of approximately 120 is required.

CONCLUSION

In elderly patients with CHF, the 6-MWT shows satisfactory agreement when repeated 1 year later. Change in 6-MWT distance is sensitive to change in self-perceived symptoms of heart failure.

Comparative assessment of right, left, and biventricular pacing in patients with permanent atrial fibrillation

AIMS

Left ventricular (LV) and biventricular (BiV) pacing are potentially superior to right ventricular (RV) apical pacing in patients undergoing atrioventricular (AV) junction ablation and pacing for permanent atrial fibrillation.

METHODS AND RESULTS

Prospective randomized, single-blind, 3-month crossover comparison between RV and LV pacing (phase 1) and between RV and BiV pacing (phase 2) performed in 56 patients (70+/-8 years, 34 males) affected by severely symptomatic permanent atrial fibrillation, uncontrolled ventricular rate, or heart failure. Primary endpoints were quality of life and exercise capacity. Compared with RV pacing, the Minnesota Living with Heart Failure Questionnaire (LHFQ) score improved by 2 and 10% with LV and BiV pacing, respectively, the effort dyspnoea item of the Specific Symptom Scale (SSS) changed by 0 and 2%, the Karolinska score by 6 and 14% (P<0.05 for BiV), the New York Heart Association (NYHA) class by 5 and 11% (P<0.05 for BiV), the 6-min walked distance by 12 (+4%) and 4 m (+1%), and the ejection fraction by 5 and 5% (P<0.05 for both). BiV pacing but not LV pacing was slightly better than RV pacing in the subgroup of patients with preserved systolic function and absence of native left bundle branch block. Compared with pre-ablation measures, the Minnesota LHFQ score improved by 37, 39, and 49% during RV, LV, and BiV pacing, respectively, the effort dyspnoea item of the SSS by 25, 25, and 39%, the Karolinska score by 39, 42, and 54%, the NYHA class by 21, 25, and 30%, the 6-min walking distance by 35 (12%), 47 (16%), and 51 m (19%) and the ejection fraction by 5, 10, and 10% (all differences P<0.05).

CONCLUSIONS

Rhythm regularization achieved with AV-junction ablation improved quality of life and exercise capacity with all modes of pacing. LV and BiV pacing provided modest or no additional favourable effect compared with RV pacing.

Selection of endpoints for heart failure clinical trials

In assessing the efficacy and the safety of a new drug, randomized clinical trials represent the standard scientific method. The selection of the best response variables in a clinical trial of a treatment in congestive heart failure patients is often not straightforward; the primary end point of a trial should be clinically relevant, directly related to the primary goal of the trial, and with favorable distributional properties. All-cause mortality is undoubtedly the most unbiased endpoint, but there is interest both in assessing cause-specific mortality and hospitalization rate and in evaluating 'soft' endpoints (functional status, exercise tolerance); the latter, in fact, are clinically relevant and potentially more useful in mild heart failure patients. Physiopathologic variables (e.g. left ventricular function) could provide information on drug action mechanism. In this paper, several recent large clinical trials are reviewed and the advantages and drawbacks of the response variables used, are analyzed.

Beta-blockers for chronic heart failure: surviving longer but feeling better?

Beta-blockers, as determined by four landmark placebo-controlled studies, impart a significant survival advantage to the chronic heart failure population. What ancillary benefits might be expected from beta-blockade, in terms of symptom relief and improvement in exercise capacity, is less clear. This situation in part reflects the heterogeneity of tools used to quantify quality of life and exercise performance as well as factors concerning the statistical handling of symptom and exercise data. In this review we explore the methodology and results of over 20 trials of carvedilol, metoprolol and bisoprolol where quality of life and measures of exercise capacity were end-points. A consistent message relating to a benefit from beta-blockade on these outcomes was elusive but the finding that patients on beta-blockers did at least as well as patients prescribed placebo was a unanimous verdict. There remains a dearth of data to help identify those patients that are at high risk of adverse events from beta-blocker therapy.

Measurement of cardiac functioning in older adults with heart failure after exercise

Although the length of a hospital stay is very limited for patients with heart failure, many patients attempt to resume some activities of daily living soon after arrival at home. Home care nurses routinely assess symptoms indicative of recurrent heart failure and the need for hospital readmission. The purpose of this comparative study was to determine whether there was a significant difference in diastolic blood pressure and oxygen saturation after walking for 6 min. Twenty adults with heart failure in an outpatient cardiology clinic were evaluated after the 6-min walk test. Although diastolic blood pressure and oxygen saturation were not significantly different after walking for 6 min, functional status was significantly related to oxygen saturation. Further study with home care clients is needed to evaluate the relation between activity and oxygen saturation.

Antiremodeling effect of long-term exercise training in patients with stable chronic heart failure: results of the Exercise in Left Ventricular Dysfunction and Chronic Heart Failure (ELVD-CHF) Trial

BACKGROUND

The effects of exercise training (ET) on left ventricular (LV) remodeling in chronic heart failure are not definitively established, and the safety of ET in these patients is still debated.

METHODS AND RESULTS

This multicenter study investigated the long-term effect of moderate ET on LV remodeling, work capacity, and quality of life (QoL) in 90 patients with stable chronic heart failure caused by LV systolic dysfunction, randomized to a 6-month ET program (T, n=45) or a control group (C, n=45). All patients underwent resting echocardiography, a cardiopulmonary exercise test, 6-minute walking test, and QoL assessment at entry and after 6 months. At entry, end-diastolic (EDV) and end-systolic (ESV) volume, ejection fraction, work capacity, peak o2, and walking distance were similar in the 2 groups. After 6 months, LV volumes diminished in T (EDV, from 142+/-26 to 135+/-26 mL/m2, P<0.006; ESV, from 107+/-24 to 97+/-24 mL/m2, P<0.05) but increased in C (EDV, from 147+/-41 to 156+/-42 mL/m2, P<0.01; ESV, from 110+/-34 to 118+/-34 mL/m2, P<0.01). Ejection fraction improved in T (P<0.001) but was unchanged in C (P=NS). Significant improvement in work capacity (P<0.001), peak VO2 (P<0.006), walking distance (P<0.001), and QoL (P<0.01) was observed in T but not in C (P=NS). T showed a trend toward fewer (P=0.05) hospital readmissions for worsening dyspnea in the absence of other adverse cardiac events.

CONCLUSIONS

In stable chronic heart failure, long-term moderate ET has no detrimental effect on LV volumes and function; rather, it attenuates abnormal remodeling. Furthermore, ET is safe and effective in improving exercise tolerance and QoL.

Exercise and muscle strength training and their effect on quality of life in patients with chronic heart failure

BACKGROUND

There is now evidence that moderate training plays an important role in the treatment of chronic heart failure. No clear instructions exist to date as to how such training programs should be carried out.

AIM

to assess the efficiency of a training program including bicycle ergometer training, moderate muscle strength training and the 6-min walk test and their influence on quality of life, anxiety and depression.

METHODS AND RESULTS

Patients (67 male, 21 female) underwent a standardized 4-week training program.

BASELINE DATA

LVEF=31+/-8%; LVEDD=143+/-59 ml; peak VO(2)=13.9+/-4.6 kg/ml. No adverse side effects could be observed. At discharge LVEF was 37+/-9%, (P=0.001); LVEDD=131+/-44ml (P=0.01); and peak VO(2)=15.4+/-5.0 kg/ml. Quality of life improved significantly in nearly all domains and in summary score. There were no significant changes in anxiety and depression. There is a negative correlation between the initial workload and changes in physical health (r=-0.42, P=0.001) and only a weak correlation between age and positive changes in physical health (r=0.26, P=0.05).

CONCLUSIONS

A standardized training program including moderate muscle strength training could be performed safely and demonstrated improvement in clinical parameters and quality of life.

Effects of exercise training in patients with heart failure: the Exercise Rehabilitation Trial (EXERT)

BACKGROUND

The purpose of this study was to examine the effects of exercise training on functional capacity in patients with heart failure.

METHODS

One hundred eighty-one patients in New York Heart Association class I to III, with ejection fraction <40% and 6-minute walk distance <500 meters, were recruited into a randomized, controlled, single-blind trial comparing 3 months of supervised training, then 9 months of home-based training with usual care.

RESULTS

There was a significant increase in 6-minute walk distance at 3 and 12 months but no between-group differences. Incremental peak oxygen uptake increased in the exercise group compared with the control group at 3 months (0.104 +/- 0.026 L/min vs 0.025 +/- 0.023 L/min; P =.026) and 12 months (0.154 +/- 0.074 L/min vs 0.024 +/- 0.027 L/min; P =.081). Compared with the control group, significant increases were observed in the exercise group for arm and leg strength. No significant changes were observed in cardiac function or quality of life. Adherence to exercise was good during supervised training but reduced during home-based training.

CONCLUSIONS

Exercise training improves peak oxygen uptake and strength during supervised training. Over the final 9 months of the study, there was little further improvement, suggesting that some supervision is required for these patients. There were no adverse effects on cardiac function or clinical events.

Reliability, validity, and responsiveness of the six-minute walk test in patients with heart failure

BACKGROUND

Our purpose was to evaluate the reliability, validity, and responsiveness of the 6-minute walk test (6MWT) in patients with heart failure (HF) enrolled in the Randomized Evaluation of Strategies for Left Ventricular Dysfunction (RESOLVD) pilot study.

METHODS

A total of 768 patients was enrolled in a multicenter randomized clinical trial evaluating the effect of candesartan, enalapril, and metoprolol on left ventricular ejection fraction (LVEF), 6MWT distance, neurohormones, and quality of life. The 6MWT was performed once at screening and twice at baseline, 18 weeks, and 43 weeks by a standardized method.

RESULTS

Test-retest reliability at baseline (intraclass correlation coefficient [ICC] = 0.90), 18 weeks (ICC = 0.88), and 43 weeks (ICC = 0.91) was very good. Baseline 6MWT distance was weakly inversely correlated to the quality-of-life cumulative score (r = -0.26, P =.0001) and moderately inversely correlated to the New York Heart Association functional classification (NYHA-FC) (r = -0.43, P =.001). In the RESOLVD study, the 6MWT was not responsive to change when effect sizes and standardized response means were used. Disease-specific quality of life was responsive to change in patients treated with candesartan and enalapril and NYHA-FC was responsive to change in the candesartan and enalapril combination and for enalapril alone with small effect sizes. The 6MWT, NYHA-FC, and quality of life were not responsive to change during the metoprolol or placebo phase.

CONCLUSIONS

The 6MWT is highly reproducible in patients with symptoms of HF. It is somewhat correlated to NYHA-FC and quality of life. Overall, quality of life was most responsive to change, whereas 6MWT and NYHA-FC were comparable but less responsive to change in the RESOLVD study.

Effects of multisite biventricular pacing in patients with heart failure and intraventricular conduction delay

BACKGROUND

One third of patients with chronic heart failure have electrocardiographic evidence of a major intraventricular conduction delay, which may worsen left ventricular systolic dysfunction through asynchronous ventricular contraction. Uncontrolled studies suggest that multisite biventricular pacing improves hemodynamics and well-being by reducing ventricular asynchrony. We assessed the clinical efficacy and safety of this new therapy.

METHODS

Sixty-seven patients with severe heart failure (New York Heart Association class III) due to chronic left ventricular systolic dysfunction, with normal sinus rhythm and a duration of the QRS interval of more than 150 msec, received transvenous atriobiventricular pacemakers (with leads in one atrium and each ventricle). This single-blind, randomized, controlled crossover study compared the responses of the patients during two periods: a three-month period of inactive pacing (ventricular inhibited pacing at a basic rate of 40 bpm) and a three-month period of active (atriobiventricular) pacing. The primary end point was the distance walked in six minutes; the secondary end points were the quality of life as measured by questionnaire, peak oxygen consumption, hospitalizations related to heart failure, the patients' treatment preference (active vs. inactive pacing), and the mortality rate.

RESULTS

Nine patients were withdrawn from the study before randomization, and 10 failed to complete both study periods. Thus, 48 patients completed both phases of the study. The mean distance walked in six minutes was 22 percent greater with active pacing (399+/-100 m vs. 326+/-134 m, P<0.001), the quality-of-life score improved by 32 percent (P<0.001), peak oxygen uptake increased by 8 percent (P<0.03), hospitalizations were decreased by two thirds (P<0.05), and active pacing was preferred by 85 percent of the patients (P<0.001).

CONCLUSIONS

Although it is technically complex, atriobiventricular pacing significantly improves exercise tolerance and quality of life in patients with chronic heart failure and intraventricular conduction delay.

A qualitative systematic overview of the measurement properties of functional walk tests used in the cardiorespiratory domain

OBJECTIVE

To perform a qualitative systematic overview of the measurement properties of the most commonly utilized walk tests in the cardiorespiratory domain: the 2-min walk test (2MWT), 6-min walk test (6MWT), 12-min walk test (12MWT), self-paced walk test (SPWT), and shuttle walk test (SWT).

DATA SOURCES

MEDLINE (1966 to January 2000) and CINAHL (1982 to December 1999) electronic databases were searched. Bibliographies of the retrieved articles were reviewed.

STUDY SELECTION

Clinical trials and observational studies were included if they reported data on the validity, reliability, interpretability, or responsiveness of the 2MWT, 6MWT, 12MWT, SPWT, or SWT. Only studies conducted on patients with cardiac and/or respiratory involvement were included.

RESULTS

Fifty-two studies examining measurement properties of the various walk tests were found: 5 studies on the 2MWT, 29 studies on the 6MWT, 13 studies on the 12MWT, 6 studies on the SPWT, and 4 studies on the SWT. Measurement properties were most strongly demonstrated for the 6MWT. Correlations of 6MWT distance and maximal oxygen consumption ranged from 0.51 to 0.90. A change in distance walked of at least 54 m was found to be clinically significant for the 6MWT. Reliability was shown to be optimized when the administration of walk tests was standardized and at least two practice walks were performed. Patients with increased likelihood of postoperative complications, hospitalization, and death were identified by analysis of distance walked.

CONCLUSIONS

Measurement properties of the 6MWT have been the most extensively researched and established. In addition, the 6MWT is easy to administer, better tolerated, and more reflective of activities of daily living than the other walk tests. Therefore, the 6MWT is currently the test of choice when using a functional walk test for clinical or research purposes.