Study objectives: To determine whether long-term IV
prostacyclin (PGI2) use improves exercise capacity in
patients with primary pulmonary hypertension (PPH).
Design: Cycle ergometry and the 6-min walk was used to
evaluate the exercise performance of patients with PPH. The patients
underwent serial exercise testing after starting continuous IV
PGI2 and were followed up for 19.5 ± 7.5 months. Peak
work, peak oxygen consumption (V̇o2), peak
O2 pulse, and distance walked in 6 min were used to
Background: PPH is characterized
by medial hypertrophy and intimal proliferation of the pulmonary
arterioles, leading to elevation of pulmonary artery pressure, right
ventricular failure, and death. Palliative treatment consists of
vasodilators, anticoagulants, cardiac glycosides, diuretics, and
transplantation. PGI2, a potent vasodilator and inhibitor
of platelet aggregation, has been used for long-term treatment when
conventional therapy has been unsuccessful.
Sixteen patients with PPH (10 women, 6 men; mean age, 24 years).
Results: At the initiation of PGI2, peak work
(± SD) was 35.5 ± 11% of predicted; peak
V̇o2, 39 ± 10.4%; peak O2
pulse, 5.0 ± 1.7 mL/min; and distance on the 6-min walk, 428 ± 78
feet. At 18 to 27 months, peak work increased to 58.8 ± 23% of
predicted (p = 0.001), peak V̇o2
increased to 52 ± 15% of predicted (p = 0.02), peak
O2 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 correlation between peak
V̇o2 and peak 6-min walk of 0.6
(p < 0.005) and 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 capacity of patients
with PPH and may be useful in guiding therapy. Patients who deteriorate
while receiving optimal conventional therapy should be considered for
IV PGI2 therapy.