Longitudinal Follow-Up of Six-Minute Walk Distance After Pulmonary Endarterectomy

Background. The 6-minute walk test is a useful tool to assess functional outcome after pulmonary endarterectomy (PEA) in chronic thromboembolic pulmonary hypertension. However, little is known about the longitudinal dynamics in functional improvement. We performed a longitudinal follow-up of 6-minute walk distance, New York Heart Association functional class, and echocardiography after PEA. Methods. We studied 71 patients with chronic thromboembolic pulmonary hypertension who underwent PEA. A 6-minute walk test and echocardiography were performed before PEA, at 3 months after, and at annual follow-up. At the time of this report, 52 patients had returned for 2-year follow-up, 32 for 3-year follow-up, 23 for 4-year follow-up, and 11 for 5-year follow-up. Results. Preoperatively, the 6-minute walk distance (6-MWD) correlated with hemodynamic severity of disease (mean pulmonary artery pressure: r = -0.55, p <0.001); total pulmonary resistance: r = -0.59, p <0.001) After PEA, 6-MWD increased from 440 +/- 109 to 524 +/- 83 meters at 1 year (n = 71, p <0.001). Further improvement was observed from 523 +/- 87 meters at 1 year to 536 +/- 91 meters at 2 years (n = 52, p <0.012). After 2 years, no further improvement was observed. At 1 year, the change in 6-MWD from baseline correlated significantly with the change observed in pulmonary hemodynamics. Changes in 6-MWD and hemodynamics were more pronounced in patients with residual pulmonary hypertension after PEA, despite the worse absolute outcome. Conclusions. In patients with chronic thromboembolic pulmonary hypertension, 6-MWD showed a gradual improvement up to 2 years after PEA. Patients with residual pulmonary hypertension benefited most from treatment, despite the worse absolute outcome. (Ann Thorac Surg 2011; 91:1094-100) (C) 2011 by The Society of Thoracic Surgeons