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

Does recovery from submaximal exercise predict response to cardiac resynchronisation therapy?

Background

Exercise parameters are not routinely incorporated in decision making for cardiac resynchronisation therapy (CRT). Submaximal exercise parameters better reflect daily functional capacity of heart failure patients than parameters measured at maximal exertion, and may therefore better predict response to CRT. We compared various exercise parameters, and sought to establish which best predict CRT response.

Methods

In 31 patients with chronic heart failure (61% male; age 68±7 years), submaximal and maximal cycling testing was performed before and 3 months after CRT. Submaximal oxygen onset (τVO₂ onset) and recovery kinetics (τVO₂ recovery), peak oxygen uptake (VO₂ peak) and oxygen uptake efficiency slope (OUES) where measured. Response was defined as ≥15% relative reduction in end-systolic volume.

Results

After controlling for age, New York Heart Association and VO₂ peak, fast submaximal VO₂ kinetics were significantly associated with response to CRT, measured either during onset or recovery of submaximal exercise (area under the curve, AUC=0.719 for both; p<0.05). By contrast, VO₂ peak (AUC=0.632; p=0.199) and OUES (AUC=0.577; p=0.469) were not associated with response. Among patients with fast onset and recovery kinetics, below 60 s, a significantly higher percentage of responders was observed (91% and 92% vs 43% and 40%, respectively).

Conclusions

Impaired VO₂ kinetics may serve as an objective marker of submaximal exercise capacity that is age-independently associated with non-response following CRT, whereas maximal exercise parameters are not. Assessment of VO₂ kinetics is feasible and easy to perform, but larger studies should confirm their clinical utility.

Effects of non-invasive ventilation in subjects undergoing cardiac surgery on length of hospital stay and cardiac-pulmonary complications: a systematic review and meta-analysis

Background

Cardiac surgery often leads to pulmonary complications. Non-invasive ventilation (NIV) is a mechanical ventilation modality that may help to prevent the pulmonary complications, and the role of the prophylactic use of NIV in patients after cardiac surgery remains controversial.

Methods

We searched PubMed, Embase, Web of Science and Cochrane Central for randomized controlled trials comparing the use of NIV (continues positive airway pressure or bi-level positive airway pressure) with standard treatment in post-cardiac surgery subjects without language restriction. Two investigators screened the eligible studies up to July, 2019. Meta-analysis using random effect model or fixed effect model was conducted for pulmonary complications, mortality, rate of reintubation and cardiac complications, and mean difference (MD) or standard mean difference for length of hospital stay and length of ICU stay.

Results

We included nine randomized controlled trails with 830 subjects. The use of NIV failed to reduce the risk of pulmonary complications, including atelectasis [risk rate (RR) 0.60; 95% confidence interval (CI): 0.28 to 1.28, P=0.19] and pneumonia (RR 0.27; 95% CI: 0.05 to 1.64, P=0.16). However, it has shortened the length of ICU stay (MD -1.00 h, 95% CI: -1.38 to -0.63, P<0.00001) and the length of hospital stay (MD -1.00 d, 95% CI: -1.12 to -0.87, P<0.00001). NIV also failed to reduce the rate of reintubation (RR 0.68; 95% CI: 0.21 to 2.26, P=0.53) or the risk of cardiac complications (RR 0.81; 95% CI: 0.59 to 1.13, P=0.22).

Conclusions

The prophylactic use of NIV immediately in post-cardiac subjects who underwent cardiac surgery might be able to shorten the length of hospital stay and the length of ICU stay, but it has no significant effect on pulmonary complications, rate of reintubation or cardiac complications.

High-intensity interval training in haemodialysis patients: a pilot randomised controlled trial

Objectives

Patients with end-stage renal disease (ESRD) undergoing haemodialysis (HD) have significantly reduced cardiorespiratory fitness and health-related quality of life (HRQoL). Our hypothesis was that high-intensity interval training (HIIT) is a feasible and safe form of exercise during HD and that HIIT would elicit greater change in cardiorespiratory fitness and HRQoL compared with moderate-intensity continuous training (MICT).

Methods

Twenty patients were randomised to either HIIT (n=6), MICT (n=8) (two times a week within 22 weeks) or usual care (n=6). Feasibility was assessed by session attendance and adherence to exercise intensity. Safety was assessed by adverse event reporting. Efficacy was determined from change in peak oxygen uptake (VO_2peak), 6 min walk distance and a HRQoL questionnaire (the COOP-WONCA chart).

Results

Eleven patients (55%) completed premeasurements and postmeasurements. The main reason for drop-out was due to kidney transplant during follow-up. The patients completed the same number of sessions in each group and adhered to the target heart rates after habituation. There were no adverse events. In the HIIT group, two of the three patients increased VO_2peak by 46% and 53%, respectively. Three of the five patients in the MICT group increased their VO_2peak by 6%, 18% and 36%, respectively.

Conclusions

This pilot study demonstrated that HIIT is a feasible and safe exercise model for intradialytic exercise in patients undergoing HD. There might be a considerable potential of intradialytic HIIT in patients undergoing HD. Further studies with larger sample sizes are needed to determine if HIIT is an optimal approach in patients with ESRD undergoing HD.

Trial registration number

NCT01728415.

Comparison of the long-term reproducibility of the walk test and of exercise peak oxygen consumption in patients with preserved exercise capacity

Short-term and long-term reproducibility of the cardiopulmonary (CPX) exercise test have been established. Though short and mid-term reproducibility of the walk test has been ascertained, this was not extensively done for the long-term reproducibility. The aim of the study was to examine the long-term reproducibility of distance walked in an allotted time and to check the stability of the relationship between walked distance and exercise peak VO₂ (pVO₂).

METHODS

Forty six subjects (33 men; 57 ± 14 years), referred for functional capacity assessment, were studied twice by CPX and walking test. On the same day, CPX was performed on a bicycle or a treadmill and walk test in a corridor as required by specific guidelines. We performed a 12-minute walk test and the distance covered in six minutes was systematically taken down. A free time interval of 1.5 hours was observed between the exercise tests. Distance walked in the allotted time and pVO₂ were analysed. Reproducibility was assessed according to Bland and Altman plots and intra-class coefficient correlation (ICC). The relationship between distance ambulated and pVO₂ was analysed by the Spearman coefficient correlation.

RESULTS

The time interval between the two evaluations was 290 ± 10 days. During this meantime, for those subjects having drug treatment, no change was recorded in their regimen. BMI remained stable for the entire studied population (28 ± 5 kg/m²). Minute walked distance was respectively 522 ± 83 and 527 ± 76 m in six minutes, 1033 ± 182 and 1041 ± 153 m in 12 minutes. pVO₂ was 21 ± 7 and 22 ± 7 ml/kg/min (all p = NS). The walk test was reproducible in the long-term, regardless of the modality (6 or 12-minute walk) as shown by the Bland-Altman plots and the high ICC of .89. Spearman's rho coefficient between distance ambulated and pVO₂ was modest and remained stable over time whatever the allotted time: Spearman's r = .54; p = .0011 (1st evaluation) and Spearman's r = .51; p = .0019 (2nd evaluation) between 6-minute distance walked and pVO₂.

CONCLUSIONS

The walking distance in an allotted time seems highly reproducible in the long-term. Its relationship with pVO₂ remains stable over time. It could be of value for repeated assessment of patients' exercise capacity in a first step. Further evaluation in a larger population is needed to confirm our result and its usefulness in clinical practice.

Heart rate recovery of individuals undergoing cardiac rehabilitation after acute coronary syndrome

BACKGROUND

An efficient cardiac rehabilitation programme (CRP) can improve the functional ability of patients after acute coronary syndrome (ACS).

OBJECTIVE

To examine the effect of a CRP on parasympathetic reactivation and heart rate recovery (HRR) measured after a 6-min walk test (6MWT), and correlation with 6MWT distance and well-being after ACS.

METHODS

Eleven normoweight patients after ACS (BMI<25kg/m²; 10 males; mean [SD] age 61 [9] years) underwent an 8-week CRP. Before (pre-) and at weeks 4 (W4) and 8 (W8) during the CRP, they performed a 6MWT on a treadmill, followed by 10-min of seated passive recovery, with HRR and HR variability (HRV) recordings. HRR was measured at 1, 3, 5 and 10min after the 6MWT (HRR1, HRR3, HRR5, HRR10), then modelized by a mono-exponential function. Time-domain (square root of the mean of the sum of the squares of differences between adjacent normal R-R intervals [RMSSD]) and frequency-domain (with high- and low-frequency band powers) were used to analyse HRV. Participants completed a mental and physical well-being questionnaire at pre- and W8. Exhaustion after tests was assessed by the Borg scale. Pearson correlation was used to assess correlations.

RESULTS

HRR3, HRR5 and HRR10 increased by 37%, 36% and 28%, respectively, between pre- and W8 (P<0.05), and were positively correlated with change in 6MWT distance (r=0.58, 0.66 and 0.76; P<0.05). Percentage change in HRR3 was positively correlated with change in well-being (r=0.70; P=0.01). Parasympathic reactivation (RMSSD) was improved only during the first 30sec of recovery (P=0.04).

CONCLUSION

Among patients undergoing a CRP after ACS, increased HRR after a 6MWT, especially at 3min, was positively correlated with 6MWT distance and improved well-being. HRR raw data seem more sensitive than post-exercise HRV analysis for monitoring functional and autonomic improvement after ACS.

Effect of prophylactic non-invasive mechanical ventilation on functional capacity after heart valve replacement: a clinical trial

OBJECTIVE

During cardiac surgery, several factors contribute to the development of postoperative pulmonary complications. Non-invasive ventilation is a promising therapeutic tool for improving the functionality of this type of patient. The aim of this study is to evaluate the functional capacity and length of stay of patients in a nosocomial intensive care unit who underwent prophylactic non-invasive ventilation after heart valve replacement.

METHOD

The study was a controlled clinical trial, comprising 50 individuals of both sexes who were allocated by randomization into two groups with 25 patients in each group: the control group and experimental group. After surgery, the patients were transferred to the intensive care unit and then participated in standard physical therapy, which was provided to the experimental group after 3 applications of non-invasive ventilation within the first 26 hours after extubation. For non-invasive ventilation, the positive pressure was 10 cm H2O, with a duration of 1 hour. The evaluation was performed on the 7th postoperative day/discharge and included a 6-minute walk test. The intensive care unit and hospitalization times were monitored in both groups. Brazilian Registry of Clinical Trials (REBeC): RBR number 8bxdd3.

RESULTS

Analysis of the 6-minute walk test showed that the control group walked an average distance of 264.34±76 meters and the experimental group walked an average distance of 334.07±71 meters (p=0.002). The intensive care unit and hospitalization times did not differ between the groups.

CONCLUSION

Non-invasive ventilation as a therapeutic resource was effective toward improving functionality; however, non-invasive ventilation did not influence the intensive care unit or hospitalization times of the studied cardiac patients.

Addition of non-invasive ventilatory support to combined aerobic and resistance training improves dyspnea and quality of life in heart failure patients: a randomized controlled trial

Objective:

To test the hypothesis that combined aerobic and resistance training and non-invasive ventilatory support result in additional benefits compared with combined aerobic and resistance training alone in heart failure patients.

Design:

A randomized, single-blind, controlled study.

Setting:

Cardiac rehabilitation center.

Participants:

A total of 46 patients with New York Heart Association class II/III heart failure were randomly assigned to a 10-week program of combined aerobic and resistance training, plus non-invasive ventilatory support ( n = 23) or combined aerobic and resistance training alone ( n = 23).

Methods:

Before and after intervention, results for the following were obtained: 6-minute walk test, forced vital capacity, forced expiratory volume at one second, maximal inspiratory muscle pressure, and maximal expiratory muscle pressure, with evaluation of dyspnea by the London Chest Activity of Daily Living scale, and quality of life with the Minnesota Living With Heart Failure questionnaire.

Results:

Of the 46 included patients, 40 completed the protocol. The combined aerobic and resistance training plus non-invasive ventilatory support, as compared with combined aerobic and resistance training alone, resulted in significantly greater benefit for dyspnea (mean change: 4.8 vs. 1.3, p = 0.004), and quality of life (mean change: 19.3 vs. 6.8, p = 0.017 ). In both groups, the 6-minute walk test improved significantly (mean change: 45.7 vs. 44.1, p = 0.924), but without a statistically significant difference.

Conclusion:

Non-invasive ventilatory support combined with combined aerobic and resistance training provides additional benefits for dyspnea and quality of life in moderate heart failure patients. Trial registration: ClinicalTrials.gov identifier: NCT02384798. Registered 03 April 2015.

Intervención psicológica como parte del tratamiento integral de pacientes con insuficiencia cardíaca: Efecto sobre la capacidad funcional

El objetivo del presente trabajo fue investigar el efecto de una intervención psicológica cognitivo-conductual en la capacidad funcional de los pacientes con insuficiencia cardiaca, medida a través de la prueba de caminata de seis minutos. Participaron 53 pacientes, clases funcionales I y II, asignados aleatoriamente a: 1) grupo control (tratamiento médico usual, n=27, edad media 61.07±15.96, 55.6% hombres), o 2) grupo experimental (tratamiento médico usual e intervención psicológica, n=26, edad media 58.42±16.42, 65.4% mujeres). Mediante la prueba de caminata de seis minutos se evalúo la distancia recorrida en metros, el nivel de cansancio físico y el nivel de esfuerzo reportado en la escala de Borg. Las evaluaciones se realizaron antes y al final del programa de intervención, además de un seguimiento a tres meses. El programa de intervención psicológica incluyó psicoeducación, respiración diafragmática, relajación muscular progresiva y entrenamiento en solución de problemas, en cuatro sesiones de 90 minutos cada una, diferidas semanalmente. Los resultados muestran que el grupo experimental incrementó (p=0.00) la distancia recorrida y disminuyó el nivel de cansancio físico (p=0.02) y nivel de esfuerzo reportados (ns), lo cual se traduce en un mejor pronóstico. El grupo control no mostró cambios significativos. Se concluye que la intervención propuesta se adapta a las necesidades de la población con un efecto positivo en su condición de salud, por lo que se sugiere la integración de equipos interdisciplinarios que incluyan programas de intervención psicológica para mejorar la salud cardiovascular y la calidad de vida de los pacientes.

Observed change in peak oxygen consumption after aortic valve replacement and its predictors

Objective

To assess the change in peak oxygen consumption (pVO₂) and determine its outcome predictors after aortic valve replacement (AVR) for aortic stenosis (AS).

Methods

Patients with AS and preserved left ventricular ejection fraction who were referred for single AVR had cardiopulmonary exercise testing prior to and 9 months post-AVR. Predictors of outcome for pVO₂ were determined by multivariate linear and logistic regression analyses. A significant change in pVO₂ was defined as a relative change that was more than twice the coefficient of repeatability by test–retest (>10%).

Results

The pre-AVR characteristics of the 37 study patients included the following: median age (range) 72 (46–83) years, aortic valve area index (AVAI) 0.41 (SD 0.11) cm²/m², mean gradient (MG) 49.1 (SD 15.3) mm Hg and New York Heart Association (NYHA)≥II 27 (73%). Pre-AVR and post-AVR mean pVO₂ was 18.5 and 18.4 mL/kg/m² (87% of the predicted), respectively, but the change from pre-AVR was heterogeneous. The relative change in pVO₂ was positively associated with the preoperative MG (β=0.50, p=0.001) and negatively associated with brain natriuretic peptide > upper level of normal according to age and gender (β=−0.40, p=0.009). A relative increase in pVO₂ exceeding 10% was found in 9 (24%), predicted by lower pre-AVR AVAI (OR 0.18; 95% CI 0.04 to 0.82, p=0.027) and lower peak O₂ pulse (OR 0.94; 95% CI 0.88 to 0.99, p=0.045). Decreases in pVO₂ exceeding 10% were found in 11 (30%) and predicted by lower MG (OR 0.93; 95% CI 0.86 to 0.99, p=0.033).

Conclusions

Change in pVO₂ was heterogeneous. Predictors of favourable and unfavourable outcomes for pVO₂ were identified.

Value of preoperative 6-minute walk test for predicting postoperative pulmonary complications

OBJECTIVES

The objective of this study was to determine the performance of preoperative 6-minute walk test (6MWT) for predicting postoperative pulmonary complications (PPC) in high risk patients undergoing elective surgery under general anesthesia.

METHODS

A prospective cohort study was conducted in patients scheduled to undergo elective thoracic or nonthoracic surgery and indicated for preoperative pulmonary evaluation in Songklanagarind Hospital, Songkhla, Thailand. Preoperative spirometry, 6MWT were done and 30-day PPC were recorded. The multiple regression analysis and receiver operating characteristic (ROC) curves were used to analyze the variables and to compare the performance of 6MWT and spirometry tests.

RESULTS

A total of 78 participants were recruited into the study. 6MWT was done completely in all cases without any complications. Among these tests, 14 cases (17.9%) had contraindications to spirometry and two cases were unable to achieve the criteria for acceptable efforts. PPC developed in 17 cases (21%) with a high mortality (17.7%). A multiple regression analysis showed elderly, poor general health status, smoking history, low level of the mean value of forced expiratory volume in 1 second (FEV1) % predicted (by spirometry) and shorter 6-minute walk distance (6MWD) were the independent factors associated with PPC. Patients developing PPC had a significantly lower preoperative 6MWD compared with patients without PPC (256.0 ± 48.0 versus 440.0 ± 117.1 meters, p < 0.001). 6MWD of ⩽325 meters was a threshold for predicting PPC with 77% sensitivity and 100% specificity, and had a good predictive value for PPC similar to that for the FEV1 %.

CONCLUSIONS

Preoperative 6MWT is a very useful alternative test for predicting PPC in high risk patients scheduled to undergo surgery under GA.

Noninvasive ventilation and exercise tolerance in heart failure: A systematic review and meta-analysis

Background:

Patients with heart failure (HF) usually develop exercise intolerance. In this context, noninvasive ventilation (NIV) can help to increase physical performance.

Objective:

To undertake a systematic review and meta-analysis of randomized controlled trials that evaluated the effects of NIV on exercise tolerance in patients with HF.

Method:

Search Strategy: Articles were searched in the following databases: Physiotherapy Evidence Database (PEDro), Scientific Electronic Library Online (SciELO), and MEDLINE. Selection Criteria: This review included only randomized controlled trials involving patients with HF undergoing NIV, with or without other therapies, that used exercise tolerance as an outcome, verified by the distance travelled in the six-minute walk test (6MWT), VO₂peak in the cardiopulmonary test, time spent in testing, and dyspnea. Data Collection and Analysis: The methodological quality of the studies was rated according to the PEDro scale. Data were pooled in fixed-effect meta-analysis whenever possible.

Results:

Four studies were selected. A meta-analysis including 18 participants showed that the use of NIV prior to the 6MWT promoted increased distance, [mean difference 65.29 m (95% CI 38.80 to 91.78)].

Conclusions:

The use of NIV prior to the 6MWT in patients with HF may promote increased distance. However, the limited number of studies may have compromised a more definitive conclusion on the subject.

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.

Prognostic value of the six-minute walk test in end-stage renal disease life expectancy: a prospective cohort study

OBJECTIVES

The six-minute walk test has been widely used to evaluate functional capacity and predict mortality in several populations. Thus, the aim of this study was to evaluate the prognostic value of the six-minute walk test for the life expectancy of end-stage renal disease patients.

METHODS

Patients over 18 years old who underwent hemodialysis for at least six months were included. Patients with hemodynamic instability, smoking, chronic obstructive pulmonary disease, physical incapacity and acute myocardial stroke in the preceding three months were excluded.

RESULTS

Fifty-two patients (54% males; 36+11 years old) were followed for 144 months. The distance walked in the six-minute walk test was a survival predictor for end-stage renal disease patients. In the multivariate analysis, for each 100 meters walked with a 100-meter increment, the hazard ratio was 0.53, with a 95% confidence interval of 0.37-0.74. There was a positive correlation between the distance walked in the six-minute walk test and peak oxygen consumption (r = 0.508). In the multivariate analysis, each year of dialysis treatment represented a 10% increase in death probability; in the severity index analysis, each point on the scale represented an 11% increase in the death risk.

CONCLUSIONS

We observed that survival increased approximately 5% for every 100 meters walked in the six-minute walk test, demonstrating that the test is a viable option for evaluating the functional capacity in patients with end-stage renal disease.

Teste de caminhada de seis minutos para avaliação de mulheres com fatores de risco cardiovascular

INTRODUÇÃO: A atividade física é uma das formas de prevenção ao aparecimento de fatores de risco cardiovascular, como a hipertensão arterial sistêmica (HAS) e o diabetes mellitus (DM). Uma das formas de avaliar é o teste de caminhada de seis minutos (TC6), que é um teste submáximo, simples de ser realizado, de baixo custo e alta reprodutibilidade. OBJETIVOS: Comparar o desempenho funcional de mulheres portadoras de risco cardiovascular, por meio do TC6. MÉTODOS: 45 mulheres foram alocadas em três grupos: G1 (com diagnóstico de HAS DM), G2 (diagnóstico de HAS) e G3 (voluntárias saudáveis). Inicialmente, as voluntárias realizaram o TC6 com caráter de aprendizado e uma hora depois o teste com caráter avaliativo. Considerou-se como variáveis pré e pós-teste a saturação periférica de oxigênio, a frequência cardíaca, a pressão arterial, a glicose e a distância percorrida. A análise estatística foi realizada com significância estipulada de p < 0,05. RESULTADOS: Todos os grupos aumentaram significativamente a distância percorrida no teste avaliativo, e tiveram acréscimo na pressão arterial e redução do índice glicêmico. CONSIDERAÇÕES FINAIS: O TC6 pode ser utilizado para avaliação da capacidade funcional de mulheres portadoras de HAS e DM como fatores de risco cardiovascular, demonstrando-se seguro e submáximo.

Teste de caminhada de seis minutos: uma ferramenta valiosa na avaliação do comprometimento pulmonar

Nos últimos anos, o uso de testes de exercício é reconhecido como um método conveniente na avaliação da função respiratória em função da necessidade de se conhecer as reservas dos vários sistemas corporais a fim de que uma ideia mais completa sobre as capacidades funcionais do paciente seja obtida. Visto que o ato de andar é uma das principais atividades da vida diária, os testes de caminhada têm sido propostos para medir o estado ou a capacidade funcional do paciente. O teste de caminhada de seis minutos provou ser reprodutível e é bem tolerado pelos pacientes. Ele avalia a distância que uma pessoa pode percorrer sobre uma superfície plana e rígida em seis minutos e tem como principal objetivo a determinação da tolerância ao exercício e da saturação de oxigênio durante um exercício submáximo. Nesta revisão, apresentamos várias áreas clínicas nas quais o teste pode fornecer informações úteis.

Design and rationale of the assessment of proper physiologic response with rate adaptive pacing driven by minute ventilation or accelerometer (APPROPRIATE) trial

Rate-adaptive sensors are designed to restore a physiologic heart rate response to activity, in particular for patients that have chronotropic incompetence (CI). Limited data exist comparing two primary types of sensors; an accelerometer (XL) sensor which detects activity or motion and a minute ventilation (MV) sensor, which detects the product of respiration rate and tidal volume. The APPROPRIATE study will evaluate the MV sensor compared with the XL sensor for superiority in improving functional capacity (peak VO(2)) in pacemaker patients that have CI. This study is a double-blind, randomized, two-arm trial that will enroll approximately 1,000 pacemaker patients. Patients will complete a 6-min walk test at the 2-week visit to screen for potential CI. Those projected to have CI will advance to a 1-month visit. At the 1-month visit, final determination of CI will be done by completing a peak exercise treadmill test while the pacemaker is programmed to DDDR with the device sensors set to passive. Patients failing to meet the study criteria for CI will not continue further in the trial. Patients that demonstrate CI will be randomized to program their rate-adaptive sensors to either MV or XL in a 1:1 ratio. The rate-adaptive sensor will be optimized for each patient using a short walk to determine the appropriate response factor. At a 2-month visit, patients will complete a CPX test with the rate-adaptive sensors in their randomized setting.

Norepinephrine remains increased in the six-minute walking test after heart transplantation

OBJECTIVE

We sought to evaluate the neurohormonal activity in heart transplant recipients and compare it with that in heart failure patients and healthy subjects during rest and just after a 6-minute walking test.

INTRODUCTION

Despite the improvements in quality of life and survival provided by heart transplantation, the neurohormonal profile is poorly described.

METHODS

Twenty heart transplantation (18 men, 49+/-11 years and 8.5+/-3.3 years after transplantation), 11 heart failure (8 men, 43+/-10 years), and 7 healthy subjects (5 men 39+/-8 years) were included in this study. Blood samples were collected immediately before and during the last minute of the exercise.

RESULTS

During rest, patients' norepinephrine plasma level (659+/-225 pg/mL) was higher in heart transplant recipients (463+/-167 pg/mL) and healthy subjects (512+/-132), p<0.05. Heart transplant recipient's norepinephrine plasma level was not different than that of healthy subjects. Just after the 6-minute walking test, the heart transplant recipient's norepinephrine plasma level (1248+/-692 pg/mL) was not different from that of heart failure patients (1174+/-653 pg/mL). Both these groups had a higher level than healthy subjects had (545+/-95 pg/mL), p<0.05.

CONCLUSION

Neurohormonal activity remains increased after the 6-minute walking test after heart transplantation.

Acute aerobic exercise reduces 24-h ambulatory blood pressure levels in long-term-treated hypertensive patients

BACKGROUND

Even with anti-hypertensive therapy, it is difficult to maintain optimal systemic blood pressure values in hypertensive patients. Exercise may reduce blood pressure in untreated hypertensive, but its effect when combined with long-term anti-hypertensive therapy remains unclear. Our purpose was to evaluate the acute effects of a single session of aerobic exercise on the blood pressure of long-term-treated hypertensive patients.

METHODS

Fifty treated hypertensive patients (18/32 male/female; 46.5+/-8.2 years; Body mass index: 27.8+/-4.7 kg/m(2)) were monitored for 24 h with respect to ambulatory (A) blood pressure after an aerobic exercise session (post-exercise) and a control period (control) in random order. Aerobic exercise consisted of 40 minutes on a cycle-ergometer, with the mean exercise intensity at 60% of the patient's reserve heart rate.

RESULTS

Post-exercise ambulatory blood pressure was reduced for 24 h systolic (126+/-8.6 vs. 123.1+/-8.7 mmHg, p=0.004) and diastolic blood pressure (81.9+/-8 vs. 79.8+/-8.5 mmHg, p=0.004), daytime diastolic blood pressure (85.5+/-8.5 vs. 83.9+/-8.8 mmHg, p=0.04), and nighttime S (116.8+/-9.9 vs. 112.5+/-9.2 mmHg, p<0.001) and diastolic blood pressure (73.5+/-8.8 vs. 70.1+/-8.4 mmHg, p<0.001). Post-exercise daytime systolic blood pressure also tended to be reduced (129.8+/-9.3 vs. 127.8+/-9.4 mmHg, p=0.06). These post-exercise decreases in ambulatory blood pressure increased the percentage of patients displaying normal 24h systolic blood pressure (58% vs. 76%, p=0.007), daytime systolic blood pressure (68% vs. 82%, p=0.02), and nighttime diastolic blood pressure (56% vs. 72%, p=0.02). Nighttime systolic blood pressure also tended to increase (58% vs. 80%, p=0.058).

CONCLUSION

A single bout of aerobic exercise reduced 24h ambulatory blood pressure levels in long-term-treated hypertensive patients and increased the percentage of patients reaching normal ambulatory blood pressure values. These effects suggest that aerobic exercise may have a potential role in blood pressure management of long-term-treated hypertensive.

The relationship between heart rate reserve and oxygen uptake reserve in heart failure patients on optimized and non-optimized beta-blocker therapy

BACKGROUND

The relationship between the percentage of oxygen consumption reserve and percentage of heart rate reserve in heart failure patients either on non-optimized or off beta-blocker therapy is known to be unreliable. The aim of this study was to evaluate the relationship between the percentage of oxygen consumption reserve and percentage of heart rate reserve in heart failure patients receiving optimized and non-optimized beta-blocker treatment during a treadmill cardiopulmonary exercise test.

METHODS

A total of 27 sedentary heart failure patients (86% male, 50+/-12 years) on optimized beta-blocker therapy with a left ventricle ejection fraction of 33+/-8% and 35 sedentary non-optimized heart failure patients (75% male, 47+/-10 years) with a left ventricle ejection fraction of 30+/-10% underwent the treadmill cardiopulmonary exercise test (Naughton protocol). Resting and peak effort values of both the percentage of oxygen consumption reserve and percentage of heart rate reserve were, by definition, 0 and 100, respectively.

RESULTS

The heart rate slope for the non-optimized group was derived from the points 0.949+/-0.088 (0 intercept) and 1.055+/-0.128 (1 intercept), p<0.0001. The heart rate slope for the optimized group was derived from the points 1.026+/-0.108 (0 intercept) and 1.012+/-0.108 (1 intercept), p=0.47. Regression linear plots for the heart rate slope for each patient in the non-optimized and optimized groups revealed a slope of 0.986 (almost perfect) for the optimized group, but the regression analysis for the non-optimized group was 0.030 (far from perfect, which occurs at 1).

CONCLUSION

The relationship between the percentage of oxygen consumption reserve and percentage of heart rate reserve in patients on optimized beta-blocker therapy was reliable, but this relationship was unreliable in non-optimized heart failure patients.