Determining prognosis in congestive heart failure: Role of the 6-minute walk test☆,☆☆,★

We propose that stage D advanced heart failure be defined as the presence of progressive and/or persistent severe signs and symptoms of heart failure despite optimized medical, surgical, and device therapy. Importantly, the progressive decline should be primarily driven by the heart failure syndrome. Formally defining advanced heart failure and specifying when medical and device therapies have failed is challenging, but signs and symptoms, hemodynamics, exercise testing, biomarkers, and risk prediction models are useful in this process. Identification of patients in stage D is a clinically important task because treatments are inherently limited, morbidity is typically progressive, and survival is often short. Age, frailty, and psychosocial issues affect both outcomes and selection of therapy for stage D patients. Heart transplant and mechanical circulatory support devices are potential treatment options in select patients. In addition to considering indications, contraindications, clinical status, and comorbidities, treatment selection for stage D patients involves incorporating the patient's wishes for survival versus quality of life, and palliative and hospice care should be integrated into care plans. More research is needed to determine optimal strategies for patient selection and medical decision making, with the ultimate goal of improving clinical and patient centered outcomes in patients with stage D heart failure.

In this manuscript we outline the development of a randomized control trial.

Heart failure (HF) is one of the leading causes of hospitalization in North America. While great advances have been made in the treatment of this disease, many factors limit the effectiveness of treatment. The objective of this Trial of Education And Compliance in Heart failure patients (TEACH) was to measure in patients with heart failure who were hospitalized and then discharged into the community, the impact of a comprehensive outpatient educational intervention on: 1) a composite endpoint of mortality, readmissions and visits to the emergency room for all causes, 2) the impact of the intervention on health-related quality of life, 3) the impact of the intervention on compliance to medication and 4) the economic impact of providing such an intervention to patients.

This was a prospective cluster randomized controlled clinical trial in patients who were admitted to hospital with a diagnosis of heart failure (HF). Patients were stratified by reason for admission to hospital. Stratum 1 included patients whose primary reason for admission was HF and stratum 2 included patients whose primary reason for hospital admission was not HF.

HF patients who receive an enhanced educational intervention from their community pharmacist will 1) have an absolute risk reduction in the number of events of 20%, 2) be more compliant, 3) will demonstrate less health-related quality of life (HRQoL) impairment as measured by disease-specific and generic HRQoL instruments and 4) will lower costs/Quality Adjusted Life Years (QALY) due to fewer total events per patient.

Outcomes were collected every 3 months from baseline to the end of 1 year. Events were tracked using a comprehensive database that we developed and validated. In order to measure compliance we used electronic measures known as Track Caps (MEMS). We also used pharmacy refill data that was provided to us from all community pharmacies the patient used. This data was analyzed and interpreted using a validated formula developed by Steiner et al. (1996).

Predicting rehospitalization risk may enable more tailored therapies for patients at high risk of rehospitalization. The objective of this study was to determine whether demographic, clinical, or psychological variables conferred increased risk of rehospitalization in a multiethnic, hospitalized, heart failure (HF) population. Demographic and clinical data were collected, with psychological and functional (6-minute walk test [6MWT]) variables obtained within 48 hours of discharge. Patients with HF (n = 72) were followed up for 90 days after discharge. Subjects’ mean age was 62 ± 18 years, with almost 1/2 nonwhite (n = 32) and 2/3 men (n = 47). Mean discharge brain natriuretic peptide was 825 ± 716 ng/L, mean quality-of-life score was 34 ± 21, and mean 6MWT distance was 186 ± 99 m. Almost 1/2 (n = 34) were rehospitalized for cardiac reasons within 90 days. Women had a 2.5 times greater risk for rehospitalization than men. Both female gender and nonwhite ethnicity incurred ≥2 times greater risk of cardiac rehospitalization. Brain natriuretic peptide and 6MWT score did not predict rehospitalization risk. In conclusion, sociodemographic factors may be more powerful predictors of rehospitalization than known clinical markers in multiethnic patients hospitalized for HF. Evaluation for support services is needed to prevent rehospitalization, especially in women and nonwhites.

The aim of the study was to correlate the score derived from Specific Activity Questionnaire (SAQ), Left Ventricular Dysfunction 36 (LVD 36) and the Minnesota Living with Heart Failure Questionnaire (LIhFE) with peak oxygen consumption measured during maximal treadmill exercise spirometry in patients with heart failure.

We prospectively studied 106 patients, average age 47 ± 15.5 (mean ± SD), with symptomatic heart failure. All were asked to answer the questions of the above mentioned questionnaires. Subsequently patients underwent treadmill exercise spirometry to measure peak oxygen consumption (VO₂ peak ml/kg/min) using the Dargie protocol and to derive functional class according to the Weber classification system.

SAQ had a very high performance in classifying patients with a VO₂ peak < 20 ml/kg/min and those with a VO₂ peak < 14 ml/kg/min. The correlation between VO₂ peak achieved and the METs corresponding to the score derived from SAQ according to the given answers was r = 0.77 (p < 0.01). The correlation between VO₂ peak achieved and the score from LVD 36 was r = −0.74 (p < 0.01). The correlation between VO₂ peak achieved and the score from LIhFE was r = −0.71 (p < 0.01).

The Specific Activity Questionnaire, the Left Ventricular Dysfunction and the Minnesota Living with Heart Failure Questionnaire were used to predict aerobic capacity and all correlated significantly with peak VO₂ achieved from exercise spirometry. The above questionnaires represent a useful method to access heart failure patients and are valuable for those unable to undergo a treadmill test.

Kervio G, Ville NS, Leclercq C, Daubert J-C, Carré F. Intensity and daily reliability of the six-minute walk test in moderate chronic heart failure patients. Arch Phys Med Rehabil 2004;85:1513–8.

To assess the intensity and daily reliability of the six-minute walk test (6MWT) in patients with moderate chronic heart failure (CHF).

Evaluation of testing protocol.

Hospitalized care.

CHF patients under optimal drug treatment (CHF-D, n=12) or optimal drug treatment plus multisite cardiac pacing (CHF-P, n=12).

Not applicable.

Peak values of oxygen uptake (Vo₂) and heart rate during a symptom-limited, treadmill exercise test and V̇o₂, heart rate, and distance during 2 6MWT sessions (morning and afternoon). The 6MWT intensity was estimated by the ratio (%) of V̇o₂ and heart rate values measured at the end of this test in relation to the respective peak values obtained during the treadmill exercise test.

Subjects’ V̇o₂ and heart rate during the 6MWT were lower (P<.001) and were about 90% of the peak values (V̇o₂: CHF-D, 90.5%±11.1%; CHF-P, 93.0%±13.2%; heart rate: CHF-D, 90.6%±6.6%; CHF-P, 91.4%±9.6%). The distance walked during both 6MWT sessions did not differ significantly, with low coefficients of variation (≤2.0%) and high intraclass correlation coefficients (≥.98). In CHF-D only, the patients’ V̇o₂ and heart rate were significantly (P<.01, P<.05, respectively) higher during the afternoon session.

Despite an intensity significantly lower but close to that of the symptom-limited exercise test, the 6MWT was well tolerated in both CHF groups. In these populations, the 6MWT is reliable on a daily basis, for the distance walked. However, for assessing V̇o₂ and heart rate values in CHF-D patients, the 6MWT must always be performed at the same time of day.

We sought to evaluate the prognostic value of the 6-minute walk test in stable outpatients with heart failure.

We examined the association of 6-minute walk test distance and outcomes among 541 patients enrolled in the Digitalis Investigation Group trial. Patients were grouped by total distance (≤200 m, 201 m–300 m, 301 m–400 m, and >400 m) with median follow-up of 32 months. All-cause mortality for patients who walked ≤200 m was significantly higher than patients who walked >200 m (43.9% versus 23.3%, P<0.001), but mortality was comparable among patients who walked >200m (201 m–300 m: 23.7%, 301 m–400 m: 25.2%, >400 m 19.8%, P for trend 0.45). Results were similar for death due to worsening heart failure (≤200 m: 29.3%, 201 m–300 m: 7.6%, 301 m–400 m: 6.7%, >400 m: 6.1%, P for trend <0.001). In multivariable analysis, distance ≤200 m remained associated with increased mortality (≤200 m: hazard ratio (HR) 1.47, 95% CI 0.96–2.27; >200 m: HR 1.00, Referent; P = 0.07) and death due to worsening heart failure (≤200 m: HR 2.89, 95% CI 1.54–5.41; >200 m: 1.00, Referent; P = 0.001).

The 6-minute walk test identifies patients who walk less than 200 m as being at markedly increased risk of death. Changing the 6-minute walk test to a time- and distance-based standard would improve the efficiency of the test while retaining the bulk of the prognostic information.