Reproducibility of cardiopulmonary exercise measurements in patients with pulmonary arterial hypertension

Background and objectives: As part of a recent study, cardiopulmonary exercise tests (CPETs) were used to evaluate and follow up patients with pulmonary arterial hypertension (PAH). These patients were more impaired than those in other published series evaluating CPET reproducibility. We used these patient tests to assess patient performance variability and evaluate reading variability. To achieve this end, six independent evaluators graded key CPET measurements in patients with PAH who underwent duplicate CPETs within 3 days of each other. Setting and patients: Over a 15-month period at two tertiary-care teaching hospitals, 42 patients with PAH underwent repeated, paired CPETs using cycle ergometry. Interventions and measurements: Each patient underwent one to six pairs of cycle ergometry tests to maximal tolerance. Each pair of tests was separated by 3 months, with each test in the pair separated by 1 to 3 days. Specific guidelines were given to the independent evaluators for the key measurements assessed from each CPET study: peak O₂ uptake (V̇O₂), peak heart rate, peak O₂ pulse, anaerobic threshold (AT), and end-tidal PO₂, end-tidal PCO₂, and the ventilatory equivalent for CO₂ at the AT (V̇E/V̇CO ₂@AT). Results: There were no fatalities or complications occurring among the 242 tests performed on 42 patients. The mean peak V̇O₂ was 722 mL/min or 41% of predicted; 34 patients were Weber class C or D. Using the specific guidelines to measure the variability of measurements made by the six independent evaluators, the coefficients of variation were < 2.2% for peak V̇O₂, peak heart rate, peak O₂ pulse, end-tidal values at the AT, and V̇E/V̇CO₂@AT, while for the AT, it was 8.5%. There were no significant differences in these measurements between the first and second tests of any pair or between the earlier and later sets of pairs. Conclusions: Using specific guidelines, key CPET measurements can be safely, reliably, and reproducibly assessed even in patients with severe exercise intolerance.