Pulmonary arterial compliance and exercise capacity after pulmonary endarterectomy

Patients with chronic thromboembolic pulmonary hypertension (CTEPH), despite successful pulmonary endarterectomy (PEA), can continue to suffer from a limitation in exercise capacity. The objective of this study was to assess whether pulmonary arterial compliance is a predictor of exercise capacity after PEA. Right heart haemodynamics, treadmill incremental exercise test, spirometry, carbon monoxide transfer factor, arterial blood gas and echocardiographic examinations were retrospectively analysed in a population of CTEPH patients who underwent PEA at a single centre. Baseline and 3-month haemodynamic data were available in 296 patients; 5-year follow-up data were available in 68 patients. In a multivariable model the following parameters were found to be independent predictors of exercise capacity after surgery: age, sex, pulmonary arterial compliance, tricuspid annular plane excursion, arterial oxygen tension and carbon monoxide transfer factor (p<0.0001); the model showed good discrimination (Harrell's c=0.84) and calibration (shrinkage coefficient=0.91). Poor exercise capacity at 3 months was loosely associated with higher death rate during subsequent survival (Harrell's c=0.61). In conclusion, after successful PEA, reduced pulmonary arterial compliance is an important determinant of exercise capacity in association with the age and sex of the patients, and the extent of recovery of both cardiac and respiratory function. However, exercise capacity does not explain a large proportion of the effect of surgery on subsequent survival.