Clinical Significance of the Pulmonary Vasodilator Response During Short-term Infusion of Prostacyclin in Primary Pulmonary Hypertension

Abstract

Background The short-term vasodilator response to prostacyclin (PGI ₂ ) in patients with primary pulmonary hypertension (PPH) is not only unpredictable but also extremely variable in magnitude. In this retrospective study, we attempted to evaluate in a nonselected population of patients with PPH the degree of vasodilatation achieved during short-term infusion of PGI ₂ and to investigate whether patients with PPH differed in terms of baseline characteristics and prognoses, according to the level of vasodilatation achieved during initial testing with PGI ₂ . Methods and Results Between 1984 and 1992, 91 consecutive patients with PPH underwent catheterization of the right side of the heart with a short-term vasodilator trial with PGI ₂ (5 to 10 ng·kg ⁻¹ ·min ⁻¹ ). According to the level of vasodilatation achieved during PGI ₂ infusion, patients were divided into three groups: nonresponding (NR, n=40), moderately responding (MR, n=42), and highly responding (HR, n=9) patients. All three groups were defined by a decrease in total pulmonary resistance index (TPRi) of 50%, respectively, relative to control values. Prolonged oral vasodilator therapy was subsequently started only in MR and HR patients. All patients had long-term oral anticoagulant therapy. The survival rate at 2 years (transplant recipients excluded) was significantly higher in HR patients compared with NR and MR patients (62% versus 38% and 47% survivors, respectively; P <.05). Comparisons between groups showed no significant differences in baseline hemodynamics or clinical characteristics except for a longer time between onset of symptoms and diagnosis (ie, first catheterization) of PPH in HR patients than in NR and MR patients (71±61 versus 35±34 and 21±21 months, respectively; P <.05). Conclusions In this study, patients with PPH exhibiting a decrease in TPRi >50% during short-term PGI ₂ challenge at the time of diagnosis had longer disease evolutions and better prognoses than patients with a lower vasodilator response.