Changes in derived measures from six-minute walk distance following home-based exercise training in congestive heart failure: A preliminary report Academic research paper on "Clinical medicine"

Indian Heart Journal 68 (2016) 527-528

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Indian Heart Journal

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Research Letter

Changes in derived measures from six-minute walk distance following home-based exercise training in congestive heart failure: A preliminary report*

ABSTRACT

Keywords:

Cardiac rehabilitation Exercise Heart failure Quality of life Six-minute walk distance

The response of derived parameters from six-minute walk distance (6MWD), like 6MW work (6MWW), to exercise training and its correlation with quality of life (QoL) in congestive heart failure (CHF) is not known. A secondary analysis from a randomized controlled trial on 30 patients (23 males; mean age 57.7 ± 10.4 years; mean ejection fraction 31 ± 10%) with CHF in NYHA class I-IV who completed an eight-week home-based exercise training program found a significant improvement in 6MWW (p < 0.05), with similar correlations between 6MWD and 6MWW with QoL. 6MWW does not appear to provide additional benefit to 6MWD in cardiac rehabilitation for CHF.

© 2016 Cardiological Society of India. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

To the Editor,

Congestive heart failure (CHF) results in severe limitations in function, as a result of a complex interplay of various physiological systems.1 Evaluation of exercise capacity has always relied upon the use of cardiopulmonary exercise testing (CPX) as the gold standard; however, this poses financial limitations in developing countries.2 An alternate method is the use of the simple, inexpensive, six-minute walk test (6MWT). However, despite its ease of use, it does have limitations. One way to overcome them is

through the use of six-minute walk work, 6MWW (i.e., body weight x distance walked), which considers the weight of the body and the force required to move this body to reduce the source of variation from r = 0.58 to r = 0.81.3,4

Since, the role of 6MWW has not been explored in patients with CHF, this preliminary study, through a secondary analysis of data, assessed the effects of a home-based exercise program on the 6MWW in patients with CHF and its correlation with quality of life.

This was a secondary analysis of a randomized controlled trial, which assessed the effects of an eight-week home-based exercise

Table 1

Demographic details and changes in six-minute walk test of participants enrolled.

Experimental (n = 15)

Control (n =15)

Sex (male:female) NYHA, median (IQR) Ejection fraction, mean ± SD Causes for HF Previous MI Hypertension Medications Diuretics Digoxin ACE inhibitors SF-36 (PCS), median (IQR) SF-36 (MCS), median (IQR)

56.87 ± 10.45 13:3 4 (4,3) 30 ± 8.8

15 9 12

33.8 (41.2,28.5) 33.4 (37.5,29)

58.73 ± 10.81 10:5 4 (4,3) 31 ± 12.5

15 8 12

32.3 (44.35,29.7) 33.2 (36.95,21.8)

Discharge

Follow-up

Discharge

Follow-up

6MWDa,b 6MWWab

423.7 ± 128.1 25,688 ± 8639

514.1 ± 134.9 31,272 ± 9555

296.4 ± 123.6 15,414 ± 6905

349.1 ± 142.5 18,081 ± 8228

a p < 0.05 between groups. b p < 0.05 within groups.

§ Disclosures: This was presented as a poster and adjudged the best poster at the National Update in Cardiology at Manipal, Karnataka, India (November 2012). http://dx.doi.org/10.1016/j.ihj.2016.05.010

0019-4832/© 2016 Cardiological Society of India. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

Research Letter/Indian Heart Journal 68 (2016) 527-528

program on functional capacity and quality of life.5 The trial involved baseline assessments of functional capacity using the 6MWD and quality of life using the Medical Outcomes Survey -short form 36 (SF36). Ethical approval was obtained and participants provided written informed consent prior to participation in this study. Baseline evaluations and follow-up evaluations of 6MWD and QoL were performed through a nonblinded method. The experimental group received a structured home-based exercise program, while the control group received physician-directed advice on physical activity/exercise. Patients were followed up weekly by telephone and reviewed at the end of eight weeks with the exercise logs for final evaluation.

A total of 30 patients meeting the inclusion criteria were recruited into this trial. Further details on the flow of participants according to the CONSORT have already been described in a previous publication.5 The demographic details of the participants and the changes observed following home-based exercise training are given in Table 1. Correlations between 6MWD and 6MWW with both the components of the SF36 showed moderate correlation at discharge. However, at follow-up, both the 6MWT and 6MWW show good correlation with the physical component of the SF36 (r = 0.882; p < 0.001 and r = 0.801; p < 0.001).

This preliminary work suggests there is no additional benefit of using 6MWW, even though it better represents the work of walking than the 6MWD alone.3 The good correlations with QoL, especially the PCS component of SF36, suggest that the 6MWW is as good as the 6MWT, when tested against each other. In addition, both the derived variables of the 6MWT showed a good response to exercise training as well. However, this could also be due to the inclusion of the 6MWD in these derived measures. Therefore, there may not be an additional benefit to the use of 6MWW over the 6MWD in cardiac rehabilitation for CHF.

Funding

None declared. Conflicts of interest

The authors have none to declare.

References

1. DowningJ, Balady GJ. The role of exercise training in heart failure. J Am Coll Cardiol. 2011;58(6):561-569.

2. Babu AS, Myers J, Arena R, Maiya AG, Padmakumar R. Evaluating exercise capacity in patients with pulmonary arterial hypertension. Expert Rev Cardiovasc Ther. 2013;11(6):729-737.

3. Chuang ML, Lin IF, Wasserman K. The body weight-walking distance product as related to lung function, anaerobic threshold and peak VO2 in COPD patients. Respir Med. 2001;95:618-626.

4. Carter R, Holiday DB, Nwasuruba C, Stocks J, Grothues C, Tiep B. 6-Minute walk work for assessment of functional capacity in patients with COPD. Chest. 2003;123(5):1408-1415.

5. Babu AS, Maiya AG, George MM, Padmakumar R, Gudattu V. Effects of early inpatient cardiac rehabilitation along with a structured home based program among patients with congestive heart failure: a randomized controlled trial. Heart Views. 2011;12:99-103.

Abraham Samuel Babu* Department of Physiotherapy, School of Allied Health Sciences, Manipal University, Manipal 576104, Karnataka, India

Charmie V. Desaia,b

aDepartment of Physiotherapy, School of Allied Health Sciences, Manipal University, Manipal 576104, Karnataka, India bYOURPHYSIO, Mumbai, India

Arun G. Maiya

Department of Physiotherapy, School of Allied Health Sciences, Manipal University, Manipal 576104, Karnataka, India

Vasudeva Guddattu

Department of Statistics, Manipal University, Manipal 576104,

Karnataka, India

Ramachandran Padmakumar Department of Cardiology, Kasturba Medical College, Manipal University, Manipal 576104, Karnataka, India

*Corresponding author E-mail address: abrahambabu@gmail.com (A.S. Babu).

Received 16 May 2016 Available online 1 June 2016