Exercise Testing to Estimate Survival in Pulmonary Hypertension

GROEPENHOFF, H., A. VONK-NOORDEGRAAF, A. BOONSTRA, M. D. SPREEUWENBERG, P. E. POSTMUS, and H. J. BOGAARD. Exercise Testing to Estimate Survival in Pulmonary Hypertension. Med. Sci. Sports Exerc., Vol. 40, No. 10, pp. 1725-1732, 2008. Background: The 6-min walk distance (6MWD) predicts survival in pulmonary hypertension (PH). The peak oxygen consumption (V)over dotO(2peak) measured during a cardiopulmonary exercise test (CPET) also relates to survival in PH, and it is unknown how the prognostic information from measurements of ventilatory responses and gas exchange during CPET compares to the prognostic information obtained by the 6MWD alone. The aims of our study were to compare prognostic values of different exercise parameters in PH and to assess whether CPET adds prognostic value to the information from the 6MWD. Methods: After baseline fight-heart catheterization and exercise testing, survival was assessed in a cohort of 115 PH patients. Results: During the 4 yr of follow-up, 18 patients died. At baseline, pulmonary arterial pressure was 49 +/- 17 mm Jig, the slope relating minute ventilation to carbon dioxide output ((V)over dot(E)/(V)over dotCO(2slope) = 45 +/- 11, (V)over dotO(2peak) = 15 +/- 6 mL.kg(-1).min(-1), increase in O-2 pulse from rest to peak exercise (Delta O-2 Pulse) = 5 +/- 2 mL.beat(-1), and 6MWD = 445 +/- 128 in. For the prediction of mortality, the areas under the receiver operating curves were very similar for the different parameters and ranged from 0.69 to 0.74. Patients with a (V)over dotCO(2slope) < 48, (V)over dotO(2peak) > 13.2 mL.kg(-1).min(-1), Delta O-2 pulse > 3.3 mL.beat(-1), or a 6MWD > 399 m had a higher cumulative survival (P < 0.05). Multivariable Cox regression with a forward selection procedure showed that only Delta O-2 Pulse improved the univariate 6MWD prediction model significantly (P < 0.05). Conclusion: CPET parameters predict survival in PH patients and add marginally to the prognostic value of the 6MWD.