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 (PAR). 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 O-2 uptake (Vo(2)), peak heart rate, peak O-2 pulse, anaerobic threshold (AT), and end-tidal Po-2, end-tidal Pco(2), and the ventilatory equivalent for CO2 at the AT (VE/VCO2@AT). Results: There were no fatalities or complications occurring among the 242 tests performed on 42 patients. The mean peak Vo(2) 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 Vo(2), peak heart rate, peak 02 pulse, end-tidal values at the AT, and VE/VCO2@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.