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

Inpatient cardiac rehabilitation soon after hospitalization for acute decompensated heart failure: a propensity score study

PURPOSE

Postdischarge management of acute decompensated heart failure (ADHF) remains an ongoing challenge. We sought to assess whether inpatient cardiac rehabilitation (CR) soon after hospitalization for ADHF improves outcome.

METHODS

Patients (N = 275) hospitalized for ADHF were enrolled. The primary outcome was a composite of all-cause mortality and urgent heart transplantation (UHT) at 1 year. The followup started at the time of discharge from the acute care setting. Because of the observational nature of the study, a propensity score analysis was used to predict the likelihood of undergoing CR. A multivariable Cox regression analysis adjusted for propensity score was used to assess the effect of CR on the primary outcome.

RESULTS

Of the 275 patients, 130 underwent CR. Among the baseline variables of the index hospitalization for ADHF, propensity score derivation identified male gender, New York Heart Association Class IV, refractory HF, moderate to severe mitral or tricuspid regurgitation, nonuse of renin-angiotensin-aldosterone system inhibitors, and daily dosage of furosemide, as being independently associated with the likelihood of undergoing CR. No patient was lost to followup. During the 12-month followup, 74 patients died and 3 underwent UHT. The overall incidence of the primary outcome was 28%. On propensity score-adjusted Cox multivariable analysis, the relative risk of the primary outcome for participants in CR compared with nonparticipants in CR was 0.58 (confidence interval [CI]: 0.34-0.99; P = .04).

CONCLUSIONS

Results suggest that the strategy of inpatient CR soon after discharge from the acute care setting improves 1-year UHT-free survival of patients with ADHF.

Prognostic factors of mid-term clinical outcome in congestive heart failure patients discharged after acute decompensation

INTRODUCTION

Risk stratification in congestive heart failure (CHF) patients is based on a variety of clinical and laboratory variables. We analysed renal function, BNP, water composition, echocardiographic and functional determinations in predicting mid-term outcome in CHF patients discharged after decompensation.

MATERIAL AND METHODS

All subjects with NYHA class II-IV were enrolled at hospital discharge. NYHA class, BNP, water body composition, non-invasive cardiac output and echocardiogram were analysed. Death, cardiac transplantation and hospital readmission for CHF were scheduled.

RESULTS

Two-hundred and thirty-seven (64.5% males, age 71.1±10.1) patients were discharged after obtaining normal hydration; left ventricular ejection fraction (LVEF) was 43.2±16.2%, cardiac output was 3.8±1.1 l/min and BNP at discharge resulted 401.3±501.7 pg/ml. During the 14-month follow-up 15 patients (6.3%) died, 1 (0.4%) underwent cardiac transplantation and 18 (7.6%) were readmitted for CHF (event group); in 203 (85.6%) no events were observed (no-event group). Higher NYHA class (2.1±0.7 vs. 1.9±0.4, p=0.01), BNP at discharge (750.2±527.3 pg/ml vs. 340.7±474.3 pg/ml, p=0.002) and impaired LVEF (33.7±15.7% vs. 44.5±15.8%, p=0.0001) and creatinine (1.7±0.6 vs. 1.2±0.8 mg/dl, p=0.004) were noticed in the event group. At multivariate Cox analysis LVEF (p=0.0009), plasma creatinine (p=0.006) and BNP at discharge (p=0.001) were associated with adverse mid-term outcome. Kaplan-Meier survival curves demonstrated that adding cut-off points for creatinine 1.5 mg/dl and discharged BNP of 250 pg/ml discriminated significantly prognosis (p=0.0001; log rank 21.09).

CONCLUSIONS

In predicting mid-term clinical prognosis in CHF patients discharged after acute decompensation, BNP at discharge ≥ 250 pg/ml added with plasma creatinine > 1.5 mg/dl are strong adverse predictors.

Baseline functional capacity and the benefit of cardiac resynchronization therapy in patients with mildly symptomatic heart failure enrolled in MADIT-CRT

BACKGROUND

Mildly symptomatic heart failure (HF) patients were shown to derive substantial clinical benefit from cardiac resynchronization therapy with defibrillator (CRT-D) in Multicenter Automatic Defibrillator Implantation Trial in Cardiac Resynchronization Therapy. However, the relationship between functional capacity (FC) and CRT-D benefit in the trial was not assessed.

OBJECTIVE

To evaluate the association between FC and response to CRT-D in Multicenter Automatic Defibrillator Implantation Trial in Cardiac Resynchronization Therapy.

METHODS

We evaluated the association between preimplantation FC and the benefit of CRT-D in reducing the risk of HF or death in Multicenter Automatic Defibrillator Implantation Trial in Cardiac Resynchronization Therapy. Functional status was assessed by a 6-minute walk test (6MWT), dichotomized at the median value as poor (<350 m) or good (≥350 m).

RESULTS

Implantable cardioverter-defibrillator-only patients with a poor FC had an adjusted 73% increased risk for HF or death (P <.001) and a 2.4-fold (P = .001) increased risk for all-cause mortality. CRT-D therapy was associated with 63% (P <.001) and 44% (P <.001) reductions in the risk of HF or death among left bundle branch block patients with a poor FC and a good FC, respectively (P for interaction = .10). Among left bundle branch block patients with a poor FC, CRT-D was also associated with a significant reduction in the risk of all-cause mortality (hazard ratio 0.52; P = .015) whereas the survival benefit of CRT-D was not observed among those who had a higher FC at enrollment (hazard ratio 1.01; P = .98; P for interaction = .10).

CONCLUSIONS

Poor FC is a strong independent predictor for mortality and HF events in patients with mildly symptomatic HF. Left bundle branch block patients with poor baseline FC derive a pronounced benefit from CRT-D, manifest by a significant reduction in mortality.

Cardiac rehabilitation in chronic heart failure: effect of an 8-week, high-intensity interval training versus continuous training

OBJECTIVE

To compare the effects of an 8-week, high-intensity interval training protocol versus continuous training.

DESIGN

Randomized controlled trial.

SETTING

Cardiac rehabilitation center.

PARTICIPANTS

Patients (N=26; mean age ± SD, 54±12y) with chronic heart failure were enrolled in a cardiac rehabilitation program for 8 weeks.

INTERVENTIONS

Patients were randomly assigned into 2 groups that performed either interval training (IT) or continuous training (CT). IT consisted of 3 sessions of 12 repetitions of 30 seconds of exercise at very high intensity, followed by 60 seconds of complete rest. The CT group performed CT exercises, which consisted of 45 minutes of aerobic exercise.

MAIN OUTCOME MEASURES

Parameters of gas exchanges: peak oxygen consumption (Vo(2)peak), first ventilator threshold (VT1), distance at six-minute walk test (6MWT), and level of anxiety and depression were measured.

RESULTS

The IT group increased significantly their Vo(2)peak, the duration of the exercise test, the oxygen pulse, oxygen consumption at the VT1, and the distance walked during the 6MWT. The CT group only increased the time at the VT1 and the distance performed at the 6MWT. The improvement in the time at the VT1 was significantly higher for the IT group than for the CT group.

CONCLUSIONS

This study shows that IT at very high intensity for patients with heart failure appears to be more effective than CT in improving indices of submaximal exercise capacity.

Gait episode identification based on wavelet feature clustering of spectrogram images

Measurement of gait parameters can provide important information about a person's health and safety. Automatic analysis of gait using kinematic sensors is a newly emerging area of research. We propose a new approach to detect gait episodes using Neural Network and and clustering of wavelet-decomposed spectrogram images. Signals from a chest-worn inertial measurement unit (IMU) is processed using Explicit Complementary Filter (ECF) to estimate and track torso angle. Using the feature obtained from wavelet decomposition of spectrogram images, we use an Augmented Radial Basis Neural Network (ARBF) to classify walking episodes. Cluster centroids of ARBF are optimized using Rapid Cluster Estimation (RCE). A pilot study of 11 participants suggests that our approach is able to distinguish between walk and non-walk activities with up to 85.71% sensitivity and 91.34% specificity.

Prediabetes influences cardiac rehabilitation in coronary artery disease patients

Background: An abnormal glucose tolerance (AGT) in coronary artery disease (CAD) patients could negatively influence recovery after an acute event but the question, relevant in the field of cardiac rehabilitation (CR), is still controversial.

Design: Prospective study, aiming to establish the prevalence of AGT and its possible influence on functional recovery in CAD patients without a previous diagnosis of diabetes mellitus (DM).

Methods: An oral glucose tolerance test was performed on 230 CAD patients without known DM, submitted to a 2-week period of intensive exercise-based CR after a recent acute myocardial infarction or coronary artery bypass graft. Functional capacity was assessed by a cardiopulmonary exercise test (CPET) and by 6-minute walking tests (6MWT) performed both on admission and at discharge.

Results: The prevalence of AGT in our population was 53%. Exercise capacity was lower in AGT patients (maximum workload achieved at CPET 79.3 ± 29.9 vs. 91.8 ± 36.9 W, p = 0.01; peak-VO2 17.8 ± 4.7 vs. 19.8 ± 5.6 ml/kg/min, p = 0.01). In the subgroup of AGT patients characterized by an inferior walking capacity at baseline, the increment in the distance walked was less than in the controls (Δ6MWT: 81.9 ± 60.1 vs. 109.1 ± 72.1, p = 0.04). An independent, negative, association was observed between AGT and Δ6MWT in patients with lower baseline test, and between maximum workload and peak-VO2 in the whole population.

Conclusions: A high prevalence of AGT was observed in a population of CAD patients without known DM after an acute coronary event. AGT is associated to a lower functional recovery, and to a reduced exercise capacity at the end of CR.

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.

The six-minute walk test: a useful metric for the cardiopulmonary patient

Measurement of exercise capacity is an integral element in assessment of patients with cardiopulmonary disease. The 6-min walk test (6MWT) provides information regarding functional capacity, response to therapy and prognosis across a range of chronic cardiopulmonary conditions. A distance less than 350 m is associated with increased mortality in chronic obstructive pulmonary disease, chronic heart failure and pulmonary arterial hypertension. Desaturation during a 6MWT is an important prognostic indicator for patients with interstitial lung disease. The 6MWT is sensitive to commonly used therapies in chronic obstructive pulmonary disease such as pulmonary rehabilitation, oxygen, long-term use of inhaled corticosteroids and lung volume reduction surgery. However, it appears less reliable to detect changes in clinical status associated with medical therapies for heart failure. A change in walking distance of more than 50 m is clinically significant in most disease states. When interpreting the results of a 6MWT, consideration should be given to choice of predictive values and the methods by which the test was carried out.

Psychological distress and mortality in systolic heart failure

BACKGROUND

Depression, anxiety, and type D ("distressed") personality (tendency to experience negative emotions paired with social inhibition) have been associated with poor prognosis in coronary heart disease, but little is known about their role in chronic heart failure. Therefore, we investigated whether these indicators of psychological distress are associated with mortality in chronic heart failure.

METHOD AND RESULTS

Consecutive outpatients with chronic heart failure (n=641; 74.3% men; mean age, 66.6+/-10.0 years) filled out a 4-item questionnaire to assess mixed symptoms of anxiety and depression and the 14-item type D scale. End points were defined as all-cause and cardiac mortality. After a mean follow-up of 37.6+/-15.6 months, 123 deaths (76 due to cardiac cause) were recorded. Cumulative hazard functions for elevated anxiety/depression symptoms differed marginally for all-cause (P=0.06), but not cardiac, mortality (P=0.43); type D personality was associated with neither all-cause mortality (P=0.63) nor cardiac mortality (P=0.87). In multivariable analyses, neither elevated anxiety/depression symptoms nor type D personality was associated with all-cause mortality (hazard ratio [HR]=1.18; 95% CI, 0.76 to 1.84; P=0.45 and HR=1.09; 95% CI, 0.67 to 1.77; P=0.73, respectively) or cardiac mortality (HR=1.13; 95% CI, 0.63 to 2.04; P=0.65 and HR=1.16; 95% CI, 0.62 to 2.18; P=0.67). In secondary analyses, a 1-point increase in anxiety/depression (range, 0 to 16) was associated with an 8% increase in risk for all-cause mortality (HR=1.08; 95% CI, 1.01 to 1.15; P=0.02).

CONCLUSIONS

Neither elevated anxiety/depression symptoms nor type D personality was associated with an increased risk for all-cause or cardiac mortality. Future studies with adequate power and a longer follow-up duration are needed to further elucidate the role of psychological distress in chronic heart failure.

The effects of METhotrexate therapy on the physical capacity of patients with ISchemic heart failure: a randomized double-blind, placebo-controlled trial (METIS trial)

BACKGROUND

The cytokine hypothesis suggests that there is an association between chronic heart failure (CHF) and inflammation. Methotrexate could improve CHF patients' clinical status, especially those with ischemic etiology.

METHODS AND RESULTS

METIS is a randomized, double-blinded trial studying 50 patients with ischemic CHF given methotrexate (7.5mg) or placebo, plus folic acid (5mg), for 12 weeks. The primary end point was the difference in 6-minute walk test (6MWT) distance before and after treatment. We also evaluated functional class (NYHA), Short-Form 36 protocol quality of life, C-reactive protein (CRP), incidence of adverse effects, and the combined incidence of death, myocardial infarction, stroke, hospitalization, and need for myocardial revascularization. There was no significant difference between groups in distance covered in the 6MWT: the methotrexate group improved by 24.5+/-39.5m, the placebo group by 21.3+/-43.7m (P=.80). The NYHA scores improved in 66.7% of the methotrexate group patients and in 50.0% of the placebo group (P=.2). SF-36 scores indicated improved mental health in the placebo group. There were no significant differences in CRP levels, the combined outcome, or adverse events.

CONCLUSIONS

These results show that the methotrexate group tended toward improved NYHA scores and that there were no significant changes in 6MWT results or secondary assessments.

Quality of life in a diverse population of patients with heart failure: BASELINE FINDINGS FROM THE HEART FAILURE ADHERENCE AND RETENTION TRIAL (HART)

PURPOSE

The exact role of psychosocial status in quality of life (QOL) of patients with heart failure (HF) is not fully clarified. This report investigates the association of depression and social support in 2 subdomains of QOL, overall satisfaction with QOL (S-QOL) and limitations in physical functioning (PF-QOL) in a diverse group of HF patients.

METHODS

Baseline data were used from a behavioral clinical trial, with complete information on 695 HF patients, of whom 33% were black and 24% had diastolic dysfunction. Data were collected via structured questionnaires, medical record review, and a 6-minute walk test. QOL outcomes included the Quality of Life Index (QLI) as a measure of S-QOL and the 36-item Short-Form Health Survey Physical Functioning (SF-36 PF) scale as a measure of PF-QOL.

RESULTS

After adjustment for sociodemographic variables, clinical and functional characteristics of disease status accounted for 19% of the variance in the QLI. Depressive symptoms and social support were significantly associated with QLI scores (P < .001) and accounted for an additional 26% of the variance. Clinical and functional characteristics accounted for 33% of the variance in SF-36 PF scores, whereas depressive symptoms and social support accounted for an additional 1% of the variance.

CONCLUSION

Depression and social support play a substantially greater role in S-QOL than in perceived limitations in basic physical functions. Targeting depression and low social support may be more important to improve overall QOL, whereas medical management of HF symptoms and functional capacity may have a greater impact on reducing basic physical limitations.

The 6-min walk test: clinical and research role, technique, coding, and reimbursement

FEV(1) is recommended for rating the severity of obstructive and restrictive pulmonary diseases, but it only moderately correlates with quality of life, mortality, and functional status. The 6-min walk test (6MWT) has been increasingly used in clinical practice and research studies as an objective measurement of functional status in patients with moderate-to-severe impairment. This low complexity test measures the distance a patient can quickly walk back and forth in a 30-m (100-foot) corridor in a period of 6 min, referred to as the 6-min walk distance (6MWD). The 6MWD, and in some circumstances oxygen desaturation during the 6MWT, are useful to assess response to medical interventions, to assess prognosis in various conditions, and as a single measurement of functional status. Strictly scripted test instructions and encouragement at baseline and at each minute of exercise is vital to obtain reproducible results. The 6MWT is reported using Current Procedural Terminology code 94620 (simple pulmonary stress test). This code is also appropriate for other simple exercise tests, including oxygen titration (if additional parameters are measured), exercise-induced bronchospasm evaluation using pre- and postexercise spirometry, and exercise prescription for pulmonary rehabilitation. Use of code 94620 to bill for services must be supported by significant documentation.