Response to inhaled nitric oxide predicts survival in patients with pulmonary hypertension

To examine the ability of vasodilator response to predict survival in a diverse cohort of patients with pulmonary hypertension (PH).

A total of 214 consecutive treatment-naive patients referred for invasive PH evaluation were enrolled between November 1998 and December 2008. Vasoreactivity was assessed during inhalation of 40 parts per million nitric oxide (iNO) and vasodilator responders were defined as those participants who achieved a mean pulmonary artery pressure (PAP) of ≤ 40 mm Hg and a drop in mean PAP ≥ the median for the cohort (13%). Kaplan-Meier analysis and Cox proportional hazards modeling were used to identify predictors of survival.

There were 51 deaths (25.9%) over a mean follow-up period of 2.3 years. Kaplan-Meier analysis demonstrated that vasodilator responders had significantly improved survival (P < .01). Vasodilator responders had improved survival regardless of whether or not they had idiopathic or nonidiopathic PH (P = .02, P < .01) or whether or not they had Dana Point class 1 or non-Dana Point class 1 PH (P < .01, P = .01). In multivariate modeling, advanced age, elevated right atrial pressure, elevated serum creatinine, and worsened functional class significantly predicted shorter survival (P = .01, P = .01, P = .01, P < .01), whereas vasodilator response predicted improved survival (P = .01).

Vasodilator responsiveness to iNO is an important method of risk stratifying PH patients, with results that apply regardless of clinical etiology.