Pre- and post-capillary exercise contributions to pulmonary hypertension in adults > 45 years.

Clinical differentiation of pre- versus post-capillary pulmonary hypertension can be challenging in older patients with risk factors for both pathophysiologies. The use of exercise pressure-flow relationships during hemodynamic assessment is now recommended when resting pulmonary artery wedge pressure is proximate to a threshold of 15mmHg. In this study we examined relationships between resting pulmonary artery wedge pressure and the balance of pre- and post-capillary contributions to exercise pulmonary hypertension. Patients > 45 years suspected of pre-capillary pulmonary hypertension (n=29, 72 ± 10years, 52% Female) with risk factors for left-heart disease were prospectively recruited to undergo semi-upright cycle-ergometry at time of diagnostic right-heart catheterization. Hemodynamic data, including pressure-flow slopes and contributions of transpulmonary gradient and pulmonary artery wedge pressure to mean pulmonary artery pressure, were analyzed to evaluate pre- and post-capillary contributions, respectively, at rest and during exercise. Exercise pressure-flow slopes indicated 62% with post-capillary contributions to pulmonary hypertension, and 31% with solely pre-capillary contributions. Of patients with pulmonary artery wedge pressure <12mmHg, 67% had post-capillary contributions to exercise pulmonary hypertension. Conversely, 50% of patients with pulmonary artery wedge pressure >15mmHg had pre-capillary contributions to exercise pulmonary hypertension. Exercise-associated increases in pulmonary artery pressures were more strongly associated with pre-capillary contributions regardless of post-capillary contributions or the value of resting pulmonary artery wedge pressure. In conclusion, in this population, post-capillary contributions to exercise pulmonary hypertension were commonly disclosed over a range of resting pulmonary artery wedge pressure, including <12mmHg. The severity of exercise pulmonary hypertension was determined by the pre-capillary contributions.