'This is a walking test, not a talking test': the six minute walking test in congestive heart failure

Effect of a 6-month pedometer-based walking intervention on functional capacity in patients with chronic heart failure with reduced (HFrEF) and with preserved (HFpEF) ejection fraction: study protocol for two multicenter randomized controlled trials

Background

Regular physical activity is recommended for patients with chronic heart failure to improve their functional capacity, and walking is a popular, effective, and safe form of physical activity. Pedometers have shown potential to increase the amount of walking across a range of chronic diseases, but it is unknown whether a pedometer-based intervention improves functional capacity and neurohumoral modulation in heart failure patients.

Methods

Two multicenter randomized controlled trials will be conducted in parallel: one in patients with chronic heart failure with reduced ejection fraction (HFrEF), the other in patients with chronic heart failure with preserved ejection fraction (HFpEF). Each trial will consist of a 6-month intervention with an assessment at baseline, at 3 months, at the end of the intervention, and 6 months after completing the intervention. Each trial will aim to include a total of 200 physically inactive participants with chronic heart failure who will be randomly assigned to intervention or control arms. The 6-month intervention will consist of an individualized pedometer-based walking program with weekly step goals, behavioral face-to-face sessions with a physician, and regular telephone calls with a research nurse. The intervention will be based on effective behavioral principles (goal setting, self-monitoring, personalized feedback). The primary outcome is the change in 6-min walk distance at the end of the 6-month intervention. Secondary outcomes include changes in serum biomarkers levels, pulmonary congestion assessed by ultrasound, average daily step count measured by accelerometry, anthropometric measures, symptoms of depression, health-related quality of life, self-efficacy, and MAGGIC risk score.

Discussion

To our knowledge, these are the first studies to evaluate a pedometer-based walking intervention in patients with chronic heart failure with either reduced or preserved ejection fraction. The studies will contribute to a better understanding of physical activity promotion in heart failure patients to inform future physical activity recommendations and heart failure guidelines.

Trial registration The trials are registered in ClinicalTrials.gov, identifiers: NCT03041610, registered 29 January 2017 (HFrEF), NCT03041376, registered 1 February 2017 (HFpEF)

VE/Vco2 slope and oxygen uptake efficiency slope in patients with coronary artery disease and intermediate peakVo2

BACKGROUND

Peak exercise oxygen uptake (peakVO2) is a widely used prognosticator. Novel spirometric parameters, less affected by submaximal performance, such as the rate of increase of minute ventilation per unit decrease of carbon dioxide production (VE/VCO2 slope) and the oxygen uptake efficiency slope (OUES) have recently been introduced.

AIM

To evaluate the discriminative value of OUES, as compared to VE/VCO2 slope in patients with coronary artery disease (CAD) and intermediate peakVO2 values.

METHODS AND RESULTS

Bicycle spiroergometry was applied in 214 patients with CAD (age 67+/-8 years, 85% men). OUES was strongly related to peakVO2 (r=0.79). New York Heart Association (NYHA) class, 6-min walking distance, N-terminal pro-brain natriuretic peptide (NT-proBNP), inflammatory markers, left ventricular (LV) volumes and ejection fraction were evaluated. NT-proBNP levels predicted independently VE/VCO2-slope and OUES. Patients with intermediate peakVO2 (12-18 ml/kg per min) and increased VE/VCO2-slope (> or = 35) had higher NYHA class, lower walking distance, higher NT-proBNP levels and higher LV volumes as compared to patients with a similar peakVO2 but lower VE/VCO2-slope. Similar findings were found for patients with intermediate peakVO2 and high OUES/kg (median value>15.3).

CONCLUSION

In CAD patients, OUES was strongly correlated with peakVO2. Both VE/VCO2 slope and OUES were independently associated with NT-proBNP levels. Both VE/VCO2 slope and OUES/kg were able to identify a subgroup of patients with an intermediate peakVO2 that was characterized by advanced remodelling and a higher degree of neurohumoral activation.

Reliability, validity, and sensitivity to change of the lower extremity functional scale in individuals affected by stroke

OBJECTIVE

To investigate reliability, validity, and sensitivity to change of the Lower Extremity Functional Scale (LEFS) in individuals affected by stroke. The secondary objective was to test the validity and sensitivity of a single-item linear analog scale (LAS) of function.

DESIGN

Prospective cohort reliability and validation study.

SETTING

A single rehabilitation department in an academic medical center.

PATIENTS

Forty-three individuals receiving neurorehabilitation for lower extremity dysfunction after stroke were studied. Their ages ranged from 32 to 95 years, with a mean of 70 years; 77% were men.

METHODS

Test-retest reliability was assessed by calculating the classical intraclass correlation coefficient, and the Bland-Altman limits of agreement. Validity was assessed by calculating the Pearson correlation coefficient between the instruments. Sensitivity to change was assessed by comparing baseline scores with end of treatment scores. Measurements were taken at baseline, after 1-3 days, and at 4 and 8 weeks.

MAIN OUTCOME MEASUREMENTS

The LEFS, Short-Form-36 Physical Function Scale, Berg Balance Scale, Six-Minute Walk Test, Five-Meter Walk Test, Timed Up-and-Go test, and the LAS of function were used.

RESULTS

The test-retest reliability of the LEFS was found to be excellent (ICC = 0.96). Correlated with the 6 other measures of function studied, the validity of the LEFS was found to be moderate to high (r = 0.40-0.71). Regarding the sensitivity to change, the mean LEFS scores from baseline to study end increased 1.2 SD and for LAS 1.1 SD.

CONCLUSION

LEFS exhibits good reliability, validity, and sensitivity to change in patients with lower extremity impairments secondary to stroke. Therefore, the LEFS can be a clinically efficient outcome measure in the rehabilitation of patients with subacute stroke. The LAS is shown to be a time-saving and reasonable option to track changes in a patient's functional status.

Improvement in diastolic function and left ventricular filling pressure induced by cardiac resynchronization therapy

BACKGROUND

Variable results of cardiac resynchronization therapy (CRT) on diastolic function have been described. We investigated 3 and 12 months' effect of CRT on diastolic function and left ventricular (LV) filling pressures and their relation to LV reverse remodeling.

METHODS

Fifty-two patients' (36 male, 69 +/- 8 years, QRS duration 170 +/- 29 milliseconds) echo-Doppler was performed before and 3 and 12 months after CRT. Tissue Doppler early diastolic annular (Em) and color M-mode-derived flow propagation (Vp) velocities were used to estimate LV filling pressures by E/Em and E/Vp ratios.

RESULTS

After 12 months, LV reverse remodeling (end-systolic volume decrease >15%) was observed in 58%. Despite a significantly more compromised baseline diastolic function of patients without LV reverse remodeling, multivariate analysis revealed that only LV dyssynchrony could predict LV reverse remodeling. Grades 2 and 3 diastolic function improved only in LV reverse remodeling patients (from 34% to 13% to 10%), whereas a nonsignificant increase from 59% to 67% to 72% was observed in patients without reverse remodeling. Irrespective of LV volume response, short-term symptomatic benefit was related to decreased filling pressure. However, after 12 months, E/Em and E/Vp only significantly decreased in patients with LV reverse remodeling (from 16.0 +/- 6 to 10.4 +/- 4 and 2.2 +/- 0.6 to 1.5 +/- 0.4, respectively).

CONCLUSIONS

Left ventricular reverse remodeling induced by CRT is accompanied by improvement in diastolic function and estimated LV filling pressure. Short-term symptomatic benefit was related to decreased filling pressure. However, for longer-term symptomatic improvement and decreased filling pressures, LV reverse remodeling appeared mandatory.

Tissue synchronisation imaging accurately measures left ventricular dyssynchrony and predicts response to cardiac resynchronisation therapy

BACKGROUND

Tissue synchronisation imaging (TSI) is a new technique to assess left ventricular (LV) dyssynchrony.

OBJECTIVES

The value of using TSI to automatically assess LV dyssynchrony compared with manual assessment of LV dyssynchrony from colour-coded tissue Doppler imaging (TDI), and to evaluate the value of TSI to predict response to cardiac resynchronisation therapy (CRT).

METHODS

60 symptomatic patients with heart failure with depressed LV ejection fraction (LVEF) and QRS >120 ms were evaluated clinically and echocardiographically at baseline and after 6 months of CRT. LV dyssynchrony was measured manually using velocity tracings from the colour-coded TDI and automatically using TSI. LV volumes and LVEF were assessed from two-dimensional echocardiography. Clinical responders had to exhibit an improvement in New York Heart Association functional class by > or =1 score and an improvement by > or =25% in 6 min walking distance after 6 months. Reverse LV remodelling was defined as a reduction of > or =15% LV end-systolic volume.

RESULTS

An excellent correlation was observed between LV dyssynchrony measured manually and automatically derived by TSI (r = 0.95, p<0.001). 34 patients showed clinical response after 6 months of CRT and 32 patients showed reverse remodelling. Baseline characteristics were comparable between responders and non-responders, except for more extensive LV dyssynchrony in the responders: 78 (26) vs 29 (29) ms (p<0.001) as assessed manually, and 79 (29) vs 28 (27) ms (p<0.001) as assessed with TSI. Using a cut-off value of 65 ms to define extensive LV dyssynchrony, TSI had a sensitivity of 81% with a specificity of 89% to predict reverse LV remodelling.

CONCLUSION

TSI allows automatic and reliable assessment of LV dyssynchrony and predicts reverse LV remodelling after CRT.

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.