Incremental Shuttle Walk Test as a Valuable Assessment of Exercise Performance in Patients With Pulmonary Arterial Hypertension

Abstract

Circulation Journal Official Journal of the Japanese Circulation Society http://www. j-circ.or.jp chievement of reliable results in clinical trials requires an accurate assessment technique. Many clinical trials investigating pulmonary arterial hypertension (PAH) have used the 6-min walk test (6MWT) as a clinical endpoint. Measurement of peak oxygen consumption (pV O2) and oxygen consumption at anaerobic threshold (V O2 at AT) via indirect calorimetry provides an objective, reliable and non-invasive technique to assess exercise tolerance in patients with various cardiac diseases. Furthermore, V O2 at AT describes the highest V O2 that the patient can sustain without developing lactic acidosis, and appears to be an independent marker of PAH severity. 1 In the Sitaxsentan Therapy for Pulmonary Arterial Hypertension (STRIDE-1) study, pV O2 was adopted as the clinical endpoint. 2 Measurement of pV O2, however, requires sophisticated equipment, laboratory facilities, and highly trained personnel. As a result, this test is not widely used and is often confined to large hospitals or research centers. These tests are also expensive and time-consuming, and may not be practical for frequent assessments or large groups of patients. Because of these limitations, field exercise tests such as the submaximal 6MWT have been developed as inexpensive and simple alternative measures of exercise tolerance. 3 The 6MWT measures the distance a patient can voluntarily traverse in a 6-min period. The test protocol, however, is selfpaced, difficult to standardize, and potentially influenced by motivation and encouragement. In addition, the 6MWT has only a moderate correlation with pV O2, 4 and is not a reliable predictor of mortality in patients with congestive heart failure. 5 The development of a simple objective field test that is more highly predictive of pV O2 and easily standardized and used is therefore desirable for patients with PAH.An incremental, externally paced 10-m shuttle walk test (SWT) has been developed for patients with chronic airway limitation. This test is highly reliable and reproducible after only 1 practice walk. 6 In contrast, the 6MWT requires at least 2 practice trials to obtain reliable results. 3 Most importantly, SWT performance relates strongly to pV O2 (r=0.88) in patients with chronic airway limitation, 7 and a strong relationship Background: Nearly all clinical trials investigating patients with pulmonary arterial hypertension (PAH) have used the 6-min walk test (6MWT) to evaluate exercise tolerance. The incremental shuttle walk test (SWT), however, has been proposed as a more valid and reproducible alternative to the 6MWT in the evaluation of exercise tolerance in patients with chronic obstructive pulmonary disease. The efficacy of SWT in clinical practice to evaluate the exercise capacity of patients with PAH was investigated.

Associations of Exercise Tolerance With Hemodynamic Parameters for Pulmonary Arterial Hypertension and for Chronic Thromboembolic Pulmonary Hypertension

“…However, in a recent meta-analysis of 6MWT findings for PAH patients, improvement in 6MWT results did not reflect benefits in terms of clinical outcomes 12 . The findings of our study confirm those previously reported that CPX is more effective than 6MWT for measuring maximum exercise tolerance for PH patients 13,14 . On the other hand, Lammers et al reported that 6MWT reflects symptomatic maximum exercise test compared with CPX using bicycle ergometry in PH children with a 6MWD below 300m 9 .…”

Incremental shuttle walk test distance and autonomic dysfunction predict survival in pulmonary arterial hypertension

“…20 A small study in pulmonary hypertension also noted that ISWD correlated more closely with peak oxygen consumption than 6MWT distance. 21 The ISWT has therefore been proposed as an alternative field walking test to the 6MWT in PAH, 22,23 however, there are no long-term data on the prognostic value of the ISWT or its sensitivity to change.…”

Pharmacokinetic and Pharmacodynamic Comparison of Sildenafil‐Bosentan and Sildenafil‐Ambrisentan Combination Therapies for Pulmonary Hypertension

“…Although the 6MWD is regarded as the gold standard for measuring exercise capacity, we previously reported that SWD showed a greater correlation than 6MWD with both pO 2 and AT. Thus, the shuttle walking test (SWT) is a better reflection of exercise tolerance in PAH than is 6MWD …”

“…Thus, the shuttle walking test (SWT) is a better reflection of exercise tolerance in PAH than is 6MWD. 27 Combination therapy is recommended for treatment of PAH. 2 Some clinical trials established supporting evidence for the value of combination therapy.…”