THE REPRODUCIBILITY OF SYMPTOMS DURING A SUBMAXIMAL EXERCISE TEST IN CHRONIC HEART-FAILURE

Aims The aim of this study was to evaluate the use of a submaximal tes t with a symptom limited endpoint and to measure the reproducibility o f symptoms in patients with CHF. Methods Ten patients with chronic hea rt failure were studied. Based on two maximal treadmill tests an indiv idual protocol using a constant work rate at a submaximal intensity wa s derived. The projected maximum treadmill time for the constant workr ate was between 8 and 17 min. Tests were carried out 1, 2, 4 and 6 wee ks after the maximum tests. Every 2.5 min during the submaximal test p atients recorded their symptoms of breathlessness and fatigue using co mputer automated visual analogue (VAS) and Borg CR10 scales. The measu re of reproducibility used was the proportion of total variability exp lained by the between subject variability. Results Using the VAS scale , general fatigue was reasonably reproducible ranging from 77-86%. For VAS breathlessness reproducibility ranged from 66% to 83%. Reproducib ility for breathlessness and fatigue for the Borg CR10 scale was much lower than the VAS scale. Reproducibility for the treadmill times was 51% but increased to 76% if one test of one subject was excluded. Conc lusions The use of the VAS during submaximal exercise offers a useful means of evaluating symptoms in CHF and potentially their response to treatment. These findings show that individual submaximal protocols ca n be easily prescribed for CHF patients. Using such an approach, clini cally desirable tests lasting around 12 min can be developed. These te sts are reasonably reproducible and may provide a useful means of asse ssing patient disability and the impact of treatment.