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

BACKGROUND: The short-term vasodilator response to prostacyclin (PGI2) 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 PGI2 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 PGI2. 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 PGI2 (5 to 10 ng.kg-1.min-1). According to the level of vasodilatation achieved during PGI2 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 50% during short-term PGI2 challenge at the time of diagnosis had longer disease evolutions and better prognoses than patients with a lower vasodilator response.