Incremental shuttle walk test in the assessment of patients for heart transplantation

Objective-To compare the incremental shuttle walk test (ISWT) with treadmil l exercise testing (TT) derived measurement of peak oxygen consumption (pea k Vo(2)) in patients undergoing assessment for cardiac transplantation. Design-Prospective comparison. All investigations occurred during a single period of admission for transplant assessment. Setting-Single UK cardiothoracic transplantation unit. Patients-25 patients recruited (21 men). Mean age was 53 years. Interventio ns-Patients underwent two TT of peak Vo(2) using the modified Naughton prot ocol and three (one practice) ISWT. Investigations were performed on consec utive days. Main outcome measures-Main outcome measures were repeatability of TT and IS WT assessments; relation between peak Vo(2) and distance walked in the ISWT ; and receiver operating characteristic (ROC) analysis to establish a dista nce walked in the ISWT that predicted which patients would have a peak Vo(2 ) greater than 14 ml/min/kg. Results-Both the ISWT and the TT were highly reproducible. Following the fi rst practice walk, mean (SD) ISWT distances were 400.0 (146) in (ISWT2) and 401.3 (129) in (ISWT3), r = 0.90, p < 0.0001. Mean peak Vo(2) by TT was 15 .2 (4.4) ml/kg/min (TT1) and 15.0 (4.4) ml/kg/min (TT2), r = 0.83, p < 0.00 01. The results revealed a strong correlation between distance covered in t he ISWT and peak Vo(2) obtained during TT (r = 0.73, p = 0.0001). ROC analy sis showed that a distance walked of 450 m allowed the selection of patient s with a peak Vo(2) of over 14 ml/min/kg. Conclusions-This work confirms the utility of the ISWT in the assessment of exercise capacity in patients with severe heart failure undergoing assessm ent for cardiac transplantation. ISWT may provide a widely applicable surro gate measure for peak Vo(2) estimation in this population. Shuttle distance walked may therefore allow the convenient, serial assessment of patients w ith heart failure before referral for transplantation.