Abstract 11025: Vasoreactivity to Inhaled Nitric Oxide Predicts Long-term Survival in Pulmonary Arterial Hypertension
Introduction: Pulmonary vasodilator testing is currently used to guide the use of calcium channel antagonists (CCA) in patients with pulmonary arterial hypertension (PAH). However, the utility of the pulmonary vascular response to inhaled nitric oxide (NO) in predicting clinical outcome has not been established, particularly in patients not treated with CCA. We hypothesized that vasoreactivity to inhaled NO would predict improved survival in PAH.
Methods: Eighty consecutive patients with WHO Group I PAH (age 55 ± 17 years, mean ± SD; 71% female, 95% functional class II-III) underwent vasodilator testing with inhaled NO (80 ppm with 90% O2 for 10 minutes) at the time of diagnosis. Changes in right atrial pressure (RAP), mean pulmonary artery pressure (mPAP), pulmonary capillary wedge pressure, Fick cardiac output, and pulmonary vascular resistance (PVR) were assessed for associations with long-term survival (median follow-up 2.4 years).
Results: Five-year survival for the entire cohort was 56%. Baseline PVR (850 ± 580 dyne-sec/cm5) and mPAP (49 ± 14 mmHg) did not predict survival. Patients with a ≥30% reduction in PVR (above median) with inhaled NO had a 53% relative reduction in mortality (Cox hazard ratio (HR) 0.47, 95% confidence interval (CI) 0.23–0.99, P=0.047), and those with a ≥12% reduction in mPAP (above median) with inhaled NO had a 55% relative reduction in mortality (HR 0.45, 95% CI 0.22–0.96, P=0.038). Patient groups stratified by changes in PVR and mPAP did not differ in baseline clinical or hemodynamic characteristics. Multivariate analysis showed that decreases in PVR and mPAP with inhaled NO predicted survival independent of age, baseline RAP, and subsequent treatment. In patients aged ≤65 years who were never treated with CCA (n=49), either a ≥30% reduction in PVR (HR 0.27, 95% CI 0.09–0.85, P=0.02) or a ≥12% reduction in mPAP (HR 0.24, 95% CI 0.07–0.81, P=0.02) during NO inhalation predicted improved survival. There were no adverse effects during inhaled NO administration.
Conclusions: Reduction in PVR or mPAP during short-term administration of inhaled NO is an independent predictor of survival in PAH. Acute vasodilator testing with inhaled NO identifies high risk PAH patients who may benefit from more aggressive treatment strategies.
- © 2010 by American Heart Association, Inc.