Nifedipine in pulmonary arterial hypertension. Importance of Raynaud's phenomenon.

We studied (via acute vasodilator testing with nifedipine) 27 patients with pulmonary arterial hypertension (PAH) (11 primary, 16 secondary PAH, [including six patients with Raynaud's phenomenon]) in order to identify predictors of hemodynamic response and specifically to assess whether patients with Raynaud's phenomenon and pulmonary hypertension were more likely to respond to nifedipine. Nifedipine decreased resting mean pulmonary artery (PA) pressure and pulmonary vascular resistance (PVR) in patients with Raynaud's phenomenon (delta PA - 6.8 +/- 10.5 mm Hg; delta PAD - PCW gradient - 9.3 +/- 4.7 mm Hg; delta PVR - 255 +/- 201 dynes.s.cm-5, all p less than .05) versus (delta PA 0.3 +/- 4.0 mm Hg; delta PAD - PCW gradient 0.4 +/- 5.0 mm Hg; delta PVR - 58 +/- 132 dynes.sec.cm-5, all NS), in the patients without Raynaud syndrome. These data suggest that patients with both primary and secondary PAH may benefit from nifedipine therapy, but that patients with Raynaud's phenomenon may respond particularly well, perhaps because of vasodilator-reversible pulmonary vasoconstriction. An alternative hypothesis is that prior chronic vasodilator therapy in the majority of our patients with Raynaud's phenomenon preserved pulmonary vasoreactivity.