Effects of long-term infusion of prostacyclin on exercise performance in patients with primary pulmonary hypertension

Study objectives: To determine whether long-term IV prostacyclin (PGI(2)) u se improves exercise capacity in patients with primary pulmonary hypertensi on (PPH). Design: Cycle ergometry and the B-min walk was used to evaluate the exercis e performance of patients with PPH. The patients underwent serial exercise testing after starting continuous IV PGI, and were followed up for 19.5 +/- 7.5 months. Peak work, peak oxygen consumption ((V)over dotO(2)), peak O-2 pulse, and distance walked in 6 min were used to evaluate performance. Background: PPI-I is characterized by medial hypertrophy and intimal prolif eration of the pulmonary arterioles, leading to elevation of pulmonary arte ry pressure, light ventricular failure, and death. Palliative treatment con sists of vasodilators, anticoagulants, cardiac glycosides, diuretics, and t ransplantation. PGI(2), a potent vasodilator and inhibitor of platelet aggr egation, has been used for long-term treatment when conventional therapy ha s been unsuccessful. Patients: Sixteen patients with PPH (10 women, 6 men; mean age, 24 years). Results: At the initiation of PGI(2), peak work (+/- SD) was 35.5 +/- 11% o f predicted; peak (V)over dotO(2), 39 +/- 10.4%; peak O-2 pulse, 5.0 +/- 1. 7 mL/min; and distance on the 6-min walk, 428 +/- 78 feet. At 18 to 27 mont hs, peak work increased to 58.8 +/- 23% of predicted (p = 0.001), peak (V)o ver dotO(2) increased to 52 +/- 15% of predicted (p = 0.02), peak O-2 pulse increased to 7.1 +/- 3.0 mL/beat (p = 0.004), and performance on the 6-min walk increased to 526 +/- 62 feet (p = 0.001). There was a positive correl ation between peak (V)over dotO(2) and peak 6-min walk of 0.6 (p < 0.005) a nd between peak work and peak 6-min walk of 0.6 (p < 0.005). Conclusions: Exercise capacity improved in our patients at up to 27 months of follow-up. Exercise testing is helpful in assessing the functional capac ity of patients with PPH and may be useful in guiding therapy. Patients who deteriorate while receiving optimal conventional therapy should be conside red for ni PGI(2) therapy.