Validity, reproducibility and responsiveness of the two minute step test in frail cardiac patients

Cardiac rehabilitation (CR) is considered standard of care after hospital
admission or intervention for cardiac disease, and is preceded by exercise
testing. The objective of exercise testing is to assess the safety of exercise
and to assess baseline fitness level of patients. The baseline fitness level is
used for personalising exercise prescription and evaluation of changes in
fitness during CR. The gold standard for exercise testing is a lab-based
cardiopulmonary exercise test (CPET). However, for frail patients, CPET is
burdensome and complex. A less complex, non lab-based, preferentially
home-based exercise test is potentially better suited to frail patients with
cardiac disease. Field-tests such as the six-minute walk test and shuttle walk
test have been suggested as an alternative, but are often not feasible in the
home setting. The two-minute step test (2MST), which uses the number of steps
to assess maximal exercise capacity, has been shown to be feasible in the home
setting in elderly patients. However, the 2MST has not been validated in frail
patients with cardiac disease and responsiveness to change is unknown.

1. Studying validity of the 2MST in comparison with CPET
2. Studying reproducibility of the 2MST by test-retest
3. Studying responsiveness of the 2MST to changes in physical fitness

This is an observational validation study in which we will compare the
performance of the two minute step test (2MST) to the gold standard in exercise
testing, i.e. a cardiopulmonary exercise test with gas exchange measurement
(CPET).
Subjects will be included during hospital admission after the TAVI procedure.
Subjects will be tested on three occasions, see figure 1. Initially, the
subjects will perform a CPET two to three weeks after dismissal from the
hospital. This is part of the usual intake for cardiac rehabilitation.
Additionally, after an hour of rest, they will perform the first step test
(2MST-1) with gas-exchange measurement. For reproducibility of the test, within
two to five days, a second step test (2MST-2) will be performed at home
together with mobile gas exchange measurement to assess VO2-peak. Finally, to
test responsiveness, at the end of their regular cardiac rehabilitation, a
third step test (2MST-3) will be performed together with mobile gas exchange
measurement to assess VO2-peak.

The 2MST is a submaximal exercise test. Performance of comparable submaximal
exercise tests (eg. 6-minute walk test) is part of standard care in CR and
considered safe. However musculoskeletal complaints have been reported after
performance of exercise testing. The 2MST brings no additional risk for
patients who are indicated for cardiac rehabilitation.