The association of six-minute walk work and other clinical measures to cardiopulmonary exercise test parameters in pulmonary vascular disease

INTRODUCTION: In pulmonary vascular disease exercise, abnormalities can include reduced exercise capacity, reduced oxygen pulse and elevated VE/VCO(2). The association of clinical measures such as six-minute walk work, haemodynamics, lung function and echocardiogram to peak VO(2), O(2) pulse and VE/VCO(2) has not been fully investigated in pulmonary vascular disease. AIMS: To determine the relationship of six-minute walk work and other clinical measures to peak VO(2), peak O(2) pulse and VE/VCO(2). Additionally, to investigate the ability to predict peak VO(2) from six-minute walk work and other clinical parameters. METHODS: Clinical data was retrospectively analysed from 63 chronic thromboembolic pulmonary hypertension (CTEPH) and 54 chronic thromboembolic disease (CTED) patients. Six-minute walk test measures, haemodynamics, lung function and echocardiographic measures were correlated with peak VO(2), peak O(2) pulse and VE/VCO(2). Predictive equations were developed to predict peak V̇O(2) in both CTEPH and CTED cohorts and subsequently validated. RESULTS: A number of clinical parameters correlated to peak VO(2), peak O(2) pulse and VE/VCO(2). Six-minute walk work and transfer factor for carbon monoxide demonstrated the strongest correlation to peak VO(2) and peak O(2) pulse. The validation of the predictive equations showed a variable level of agreement between measured peak VO(2) and calculated peak VO(2) from the predictive equations. CONCLUSION: Six-minute walk work and additionally a number of clinical test parameters were associated to peak VO(2), peak O(2) pulse and VE/VCO(2). Six-minute walk work and transfer factor for carbon monoxide were particularly highly correlated to peak VO(2) and similarly to peak oxygen pulse. The validation of the predictive equations showed a variable level of agreement and therefore may have limited clinical applicability.